ArticlePDF Available

Undetectable urinary free cortisol concentrations in a case of Cushing's disease

March 1999
European Journal of Endocrinology 140(2):148-51

DOI:10.1530/eje.0.1400148

Source
PubMed

Authors:

Basil George Issa

Manchester University NHS Foundation Trust

Show all 6 authorsHide

Measurement of the 24-h urinary free cortisol is a valuable screening test of endogenous hypercortisolism and, although false positive results may occur in a few situations, for example endogenous depression, false negative results are unusual. We report a case of a 48-year-old lady with pituitary-dependent Cushing's disease, whose 24-h urinary free cortisol excretion was consistently undetectable in association with increased plasma and salivary cortisol concentrations and reduced dexamethasone suppressibility. The patient had chronic renal impairment (creatinine clearance 21 ml/min) as a consequence of hypertension, despite only modestly increased urea and creatinine concentrations. Urinary free cortisol measurements must be interpreted with caution in patients with renal impairment.

Summary of baseline and dynamic tests of adrenal function.

…

mmunostaining for ACTH. (a) Background (non-adenomatous) pituitary tissue showing normal staining. Compare with sections through microadenoma (b), showing marked immunostaining for ACTH.

…

Figures - uploaded by Basil George Issa

Content may be subject to copyright.

Content uploaded by Basil George Issa

Content may be subject to copyright.

CASE REPORT

Undetectable urinary free cortisol concentrations in a case of

Cushing’s disease

B G Issa

, M D Page

, G Read

, R John

, A Douglas-Jones

and M F Scanlon

Departments of

Medicine,

Medical Biochemistry and

Histopathology, University Hospital of Wales, Cardiff and

Department of Medicine,

East Glamorgan General Hospital, Pontypridd, UK

(Correspondence should be addressed to M F Scanlon, Department of Endocrinology, University Hospital of Wales, Heath Park, Cardiff CF4 4XN, UK)

Abstract

Measurement of the 24-h urinary free cortisol is a valuable screening test of endogenous hyper-

cortisolism and, although false positive results may occur in a few situations, for example endogenous

depression, false negative results are unusual. We report a case of a 48-year-old lady with pituitary-

dependent Cushing’s disease, whose 24-h urinary free cortisol excretion was consistently undetectable

in association with increased plasma and salivary cortisol concentrations and reduced dexamethasone

suppressibility. The patient had chronic renal impairment (creatinine clearance 21 ml/min) as a

consequence of hypertension, despite only modestly increased urea and creatinine concentrations.

Urinary free cortisol measurements must be interpreted with caution in patients with renal

impairment.

European Journal of Endocrinology 140 148–151

Introduction

Several modiﬁcations in the methodology of measuring

urinary free cortisol (UFC) have been introduced since

it was ﬁrst proposed as a test of adrenal function

(1). At present, it is considered the best screening test of

endogenous hypercortisolism, assuming complete collec-

tion of urine (2). The test has superseded measurements

of the excretion of 17-hydroxycorticosteroids and

17-ketogenic steroids, which are dependent on body

weight (3) and creatinine clearance, and are less

sensitive (4, 5) than measurements of UFC. In addition,

UFC excretion is relatively simple to measure in the

laboratory.

Conditions that may lead to false positive UFC are well

recognised by most endocrinologists and physicians.

However, the causes of false negative UFC measure-

ments are not clearly identiﬁed in the literature and the

incidence varies between ‘virtually absent’ (2) to 36%

(6). Studies that have demonstrated high false negative

rates for UFC assay were all conducted in the late 1950s

and ’60s; since then, the sensitivity and speciﬁcity of the

UFC assay have improved considerably. The effects of

renal impairment on UFC are variable and reduction

of UFC excretion in Cushing’s syndrome has been

shown mostly only in severe renal impairment (creati-

nine clearance <20 ml/min) (7). We report a case of

Cushing’s disease and moderately severe renal impair-

ment with undetectable UFC concentrations.

Case report

A 48-year-old lady presented to her local hospital with

dyspnoea caused by congestive cardiac failure (CCF) and

uncontrolled hypertension. There was no signiﬁcant

past history, apart from peptic ulceration 20 years

previously. In particular, there was no history of steroid

treatment or alcohol misuse. Examination revealed an

increased blood pressure of 190/130 mmHg and signs

of biventricular failure. The patient was noted to be

Cushingoid, with a ‘moon face’, central adiposity and

slight proximal muscle weakness. There was no

evidence of a ‘buffalo hump’, supraclavicular fat pads,

ecchymosis, abdominal striae or hirsutism. She had

noticed a change in her facial appearance and easy

bruising over the past 3 years and had been amenorr-

hoeic for 1 year before presentation. Her CCF and

hypertension partially improved with frusemide, lisino-

pril and long-acting nifedipine. Plasma electrolytes,

liver function tests and full blood count were normal,

but the patient had increased urea and creatinine

concentrations (10 mmol/l and 220 mol/l respectively).

The electrocardiogram was normal. There was loss of

diurnal rhythm for cortisol and adrenocorticotrophic

hormone (ACTH), and failure of cortisol suppression

with low-dose (0.5 mg 6 hourly for 48 h), but not

high-dose (2 mg 6 hourly for 48 h) dexamethasone. A

computed tomography (CT) scan of the pituitary gland

was normal, but adrenal CT revealed bilateral adrenal

European Journal of Endocrinology (1999) 140 148–151 ISSN 0804-4643

q1999 Society of the European Journal of Endocrinology

hyperplasia. Throughout these investigations, 24-h

UFC concentrations were low normal or undetectable

(<28 nmol/24 h). Concomitant salivary cortisol con-

centrations were increased and failed to suppress with

low-dose dexamethasone, consistent with the view that

the undetectable UFC concentrations were misleading.

The results of the biochemical investigations are

summarised in Table 1. In view of the increased serum

urea and creatinine concentrations, we suspected renal

failure as the cause of low UFC. Creatinine clearance

was reduced to 21 ml/min, but ultrasound scan of the

renal tract was unremarkable. MRI of the pituitary

gland showed a 5-mm focal non-enhancing lesion in the

left side of the pituitary fossa, consistent with an

adenoma (Fig. 1). A diagnosis of pituitary-dependent

Cushing’s syndrome was made and the patient under-

went selective transsphenoidal removal of a pituitary

adenoma. Histology conﬁrmed a pituitary micro-

adenoma staining for immunoreactive ACTH (Fig. 2).

Postoperative assessment showed suppression of 0900-h

cortisol to less than 28 nmol/l with 1mg dexamethasone,

with normal pituitary function otherwise indicating cure

of her Cushing’s disease. The 24-h UFC remained

undetectable. Serum cortisol binding globulin (CBG) was

within the normal range, at 300 nmol/l (normal range

290–420 nmol/l). Antihypertensive medication was with-

drawn, with the blood pressure remaining in the normal

range. There was regression of some of the clinical

features of Cushing’s syndrome.

Methods

Serum and urinary cortisol were measured by a

competitive chemiluminescent immunoassay (Chiron

Diagnostics, East Walpole, MA, USA) on an ACS-180

automated immunoassay analyser (Chiron Diagnostics).

The method for measurement of UFC involved a prior

extraction step of the urine with dichloromethane. UFC

was also measured using an in-house extraction radio-

immunoassay, conﬁrming the UFC results obtained by

the ﬁrst technique. ACTH was measured by a two-site

chemiluminometric assay (Nichols Institute, San Juan

Capistrano, CA, USA).

Discussion

UFC represents the plasma protein unbound fraction

of cortisol that is produced by ultraﬁltration at the

glomerulus after reabsorption of most (95%) of

the ﬁltered load. Measured by HPLC or radioimmuno-

assay, it is considered the best screening test for

hypercortisolism (7, 8). Our patient had low or

undetectable UFC concentrations, despite increased

plasma and salivary cortisol concentrations secondary

to an ACTH-producing pituitary adenoma. The prob-

able explanation for this discrepancy is the effect of

renal impairment on cortisol ﬁltration by the kidney.

West (9) conﬁrmed the ﬁndings of Gilliland & Phillips

(10), who demonstrated a clear correlation between

UFC and creatinine clearance in 28 consecutive

urine samples, but found normal or increased UFC

in another group of patients with renal failure. In

contrast, Ogunlesi et al. (11) found the concentrations

of 24-h UFC excretion in 10 uraemic subjects (creati-

nine clearance <30 ml/min, ﬁxed urine speciﬁc gravity

and bilaterally shrunken kidneys on ultrasonography)

to be signiﬁcantly greater than those in nine controls.

This was in association with loss of the circadian

rhythm for cortisol secretion and failure of serum

cortisol to be suppressed in response to dexamethasone

(1 mg).

Renal failure may affect cortisol metabolism in various

ways, including alteration in the hypothalamo–

pituitary–adrenal axis (12), a prolonged half-life of

serum cortisol (13) and decreased oxidation of tetra-

hydrocortisone to tetrahydrocortisol (14). However,

this marked effect of renal impairment on UFC excretion

is not widely appreciated, and this, together with

abnormal cortisol binding, metabolite interference

with assays for serum cortisol and poor absorption

of dexamethasone from the gastrointestinal tract of

patients with renal failure, may lead to obvious

diagnostic difﬁculties.

Several investigators have suggested measuring

alternative cortisol metabolites in the urine of patients

with Cushing’s syndrome to be a superior predictor of

hypercortisolism than measurement of UFC (15–17).

EUROPEAN JOURNAL OF ENDOCRINOLOGY (1999) 140 Undetectable urinary free cortisol in Cushing’s disease 149

Table 1 Summary of baseline and dynamic tests of adrenalfunction.

Cortisol (nmol/l) ACTH (ng/l) Salivary cortisol (nmol/l) UFC

0900h 2400h 0900h 2400h 0900h 2400h (nmol/24h)

Basal 498 502 84.1 74 <28

Basal 559 504 84.3 53.4 32.4 21.6 50

Basal 646 510 86.8 76.6 41.2 20.8 <28

Low Dex, Day 1 453 18 <28

Low Dex, Day 2 254 7.6 <28

High Dex, Day 1 130 2.9 <28

High Dex, Day 2 <28 0.9 <28

Dex, dexamethasone.

Voccia et al. (17) studied 10 children with Cushing’s

syndrome and found that concentrations of urinary

6b-hydroxycortisol excretion were a better test for

hypercortisolism than was UFC or 17-hydroxycortico-

steroids. In 40 patients with pathologically proven

Cushing’s syndrome due to different causes, 20a-

dihydrocortisol was found to be a better index of

hypercortisolism than was UFC (15, 16). Despite these

observations, UFC remains the standard screening

test for hypercortisolism in most laboratories. Because

Cushing’s syndrome is usually associated with

hypertension and possible alterations in renal function,

it is imperative to recognise and, if possible, study

further the relationship between the degree of renal

impairment and excretion of UFC. Despite the known

regulatory effects of CBG on plasma cortisol transport

and clearance (18), serum CBG concentrations in our

patient were normal. Finally, the diagnosis of cyclical

Cushing’s disease was considered in our patient, but

was believed to be unlikely, as UFC concentrations

remained undetectable on many occasions and con-

commitant plasma and salivary cortisol concentrations

were increased.

In conclusion, we report a patient with Cushing’s

disease and moderately severe renal failure with

persistently low or undetectable UFC concentrations.

Further studies should investigate the effect of various

degrees of renal impairment on UFC. Clinicians should

be aware that UFC measurements can be unreliable in

patients with renal impairment, which limits the value

of this test in screening for hypercortisolism in such

patients.

150 B G Issa and others EUROPEAN JOURNAL OF ENDOCRINOLOGY (1999) 140

Figure 1 (a, b) Coronal and sagittal T1-weighted pre- and

post-gadolinium pituitary MRI scans showing a 5-mm

non-enhancing lesion (arrow) consistent with a pituitary

microadenoma.

Figure 2 Immunostaining for ACTH. (a) Background

(non-adenomatous) pituitary tissue showing normal staining.

Compare with sections through microadenoma (b), showing

marked immunostaining for ACTH.

Acknowledgements

We would like to thank Mr Colin Selby, Department of

Clinical Chemistry, City Hospital, Nottingham for

performing the cortisol-binding globulin assay.

References

1 Cope CL & Black EG. Urinary cortisol measurement in adrenocortical

hyperfunction. British Medical Journal 1959 21117–1119.

2 Tigos C, Papanicolaou DA & Chrousos GP. Advances in the

diagnoses and treatment of Cushing’s syndrome. Bailliere’s

Clinical Endocrinology and Metabolism 1995 9315–336.

3 Streeten DHP, Stevenson CT, Dalakos TG, Nicholas JJ, Dennick LG

& Fellerman H. Diagnosis of hypercortisolism. Biochemical

criteria of differentiating patients from lean and obese normal

subjects and females on oral contraceptives. Journal of Clinical

Endocrinology and Metabolism 1969 29 191–211.

4 Murphy BEP. Clinical evaluation of urinary cortisol determination

by competitive protein binding radioassay. Journal of Clinical

Endocrinology and Metabolism 1968 28 343–348.

5 Mattingly D & Tyler C. Simple screening tests for Cushing’s

syndrome. British Medical Journal 1967 4394–397.

6 Streeten DHP, Dalakos TG & Anderson Jr GH. Diagnosis and

treatment of Cushing’s syndrome. In New Concepts in Endocrinol-

ogy and Metabolism, pp 57. Eds LI Rose & RL Lavine. New York:

Grune and Stratton, 1977.

7 Burke CW & Beardwell CG. Cushing’s syndrome: an evaluation of

the clinical usefulness of urinary free cortisol and other steroid

measurements in diagnosis. Quarterly Journal of Medicine 1973 42

175–204.

8 Eddy RL, Jones AL, Gilliland PF, Ibarra JD, Thompson JQ,

MacMurray FR et al. Cushing’s syndrome: a prospective study of

diagnostic methods. American Journal of Medicine 1973 55 621–

630.

9 West P. Application of a modiﬁed Cortipac procedure for the

estimation of urinary free cortisol in various clinical situations.

Journal of Clinical Pathology 1980 33 89–92.

10 Gilliland J & Phillips PJ. Urinary free cortisol excretion and renal

function. Journal of Clinical Pathology 1978 31 671–672.

11 Ogunlesi AO, Akanji AO, Kadiri S & Osotimehin B. Uraemia and

adrenocortical function in Nigerian subjects. African Journal of

Medical Sciences 1990 19 43–48.

12 Wallace EZ, Rosman P, Toshav N, Sacerdote A & Balthazar A.

Pituitary adrenocortical function in chronic renal failure. Journal

of Clinical Endocrinology and Metabolism 1980 50 46–51.

13 Bacon GE, Kenny FM, Mardaugh HV, Richards C et al. Prolonged

serum half-life of cortisol in chronic renal failure. Johns Hopkins

Medical Journal 1973 132 127–131.

14 Vanluchene E, Vandekerckhove D, Thiery M & Van Holder R.

Changes in cortisol metabolism in various physiological and

pathological situations. Annales d’Endocrinologie 1981 42

284–285.

15 Schoneshofer M, Weber B, Oelkers W, Nahoul K & Mantero F.

Measurement of urinary free 20a-dihydrocortisol in biochemical

diagnosis of chronic hypercorticoidism. Clinical Chemistry 1986

32 808–810.

16 Schoneshofer M, Weber B & Nigam S. Increased urinary excretion

of free 20a- and 20b-dihydrocortisol in a hypercortisolemic but

hypocortisoluric patient with Cushing’s disease. Clinical Chemistry

1983 29 385–389.

17 Voccia E, Saenger P, Peterson RE, Rauh W, Gottesdiener K,

Levine L & New MI. 6b-Hydroxycortisol excretion in hyper-

cortisolemic states. Journal of Clinical Endocrinology and Metabolism

1979 48 467–471.

18 Bright GM. Corticosteroid-binding globulin inﬂuences kinetic

parameters of plasma cortisol transport and clearance. Journal of

Clinical Endocrinology and Metabolism 1995 80 770–775.

Received 7 October 1998

Accepted 7 October 1998

EUROPEAN JOURNAL OF ENDOCRINOLOGY (1999) 140 Undetectable urinary free cortisol in Cushing’s disease 151

Diagnostic challenges in pediatric Cushing's disease associated with chronic renal failure: a report of three patients

Article

Nov 2024
J PEDIATR ENDOCR MET

Objectives Cushing’s disease (CD) in the context of chronic kidney disease (CKD) is very rare. CKD causes physiological hypercortisolism making the diagnosis of CD extremely difficult. To report 3 females with CKD and CD and to outline the principles that may guide the diagnosis of CD in this context. Case presentation P1. A 12.3-year-old patient with CKD secondary to steroid-resistant nephrotic syndrome on hemodialysis (HD) and a medical history of aseptic meningitis. She was referred due to the incidental finding of pituitary macroadenoma. P2. A patient with CKD secondary to bilateral renal hypodysplasia in conservative treatment. At age 16.4 years, she had significant weight gain, purple-red stretch marks, galactorrhea, and menstrual irregularities. P3. A 15.3-year-old patient with CKD secondary to steroid resistant nephrotic syndrome in conservative treatment was referred for weight gain, secondary amenorrhea, and hypertension. In all patients, diagnosis of CD was confirmed by clinical and biochemical findings. P1 and P3 underwent transsphenoidal surgery, and in P2, transcranial surgery resection was performed. Histopathological examination revealed a corticotroph adenoma in P1 and P2, and in P3, immunohistochemistry demonstrated ACTH predominance. All patients achieved remission. P1 and P2 developed pituitary deficiencies. Conclusions To the best of our knowledge, these are the first three reported cases of the diagnostic association of CD and CKD in children. In all cases, CS was clinically suspected and CD was confirmed through complementary exams. Given the current lack of clear diagnostic criteria for CD in CKD patients, a thorough clinical evaluation remains essential for guiding the diagnosis.

Pitfalls in the Diagnosis and Management of Hypercortisolism (Cushing Syndrome) in Humans; A Review of the Laboratory Medicine Perspective

Article

Full-text available

Apr 2023

Biochemical confirmation of a diagnosis of hypercortisolism (Cushing syndrome) is vital to direct further investigations, especially given the overlap with non-autonomous conditions, such as pseudo-Cushing, and the morbidity associated with missed diagnoses. A limited narrative review was performed focusing on the laboratory perspective of the pitfalls of making a biochemical diagnosis of hypercortisolism in those presenting with presumed Cushing syndrome. Although analytically less specific, immunoassays remain cheap, quick, and reliable in most situations. Understanding cortisol metabolism can help with patient preparation, specimen selection (e.g., consideration of urine or saliva for those with possible elevations of cortisol binding globulin concentration), and method selection (e.g., mass spectrometry if there is a high risk of abnormal metabolites). Although more specific methods may be less sensitive, this can be managed. The reduction in cost and increasing ease of use makes techniques such as urine steroid profiles and salivary cortisone of interest in future pathway development. In conclusion, the limitations of current assays, particularly if well understood, do not impede diagnosis in most cases. However, in complex or borderline cases, there are other techniques to consider to aid in the confirmation of hypercortisolism.

Consensus statement by the French Society of Endocrinology (SFE) and French Society of Pediatric Endocrinology & Diabetology (SFEDP) on diagnosis of Cushing’s syndrome

Article

Feb 2022
ANN ENDOCRINOL-PARIS

Cushing’s syndrome is defined by prolonged exposure to glucocorticoids, leading to excess morbidity and mortality. Diagnosis of this rare pathology is difficult due to the low specificity of the clinical signs, the variable severity of the clinical presentation, and the difficulties of interpretation associated with the diagnostic methods. The present consensus paper by 38 experts of the French Society of Endocrinology and the French Society of Pediatric Endocrinology and Diabetology aimed firstly to detail the circumstances suggesting diagnosis and the biologic diagnosis tools and their interpretation for positive diagnosis and for etiologic diagnosis according to ACTH-independent and -dependent mechanisms. Secondly, situations making diagnosis complex (pregnancy, intense hypercortisolism, fluctuating Cushing’s syndrome, pediatric forms and genetically determined forms) were detailed. Lastly, methods of surveillance and diagnosis of recurrence were dealt with in the final section.

Zusammenhang zwischen linksventrikulärer Masse und Aktivität des Hypothalamus-Hypophysen-Systems bei Depression: Eine Studie mit Cortisol im Urin und nach Suppression mit Dexamethason

Thesis

Jan 2021

Noah Mainak Wegerich

Die hier vorliegende Arbeit beschäftigt sich mit dem Zusammenhang zwischen affektiven Störungen und dem kardiovaskulären Risiko. Besonderer Fokus lag dabei auf der Evaluation des Hypothalamus-Hypophysen-Nebennierenrinden-Systems bei depressiven Patienten. Kardiovaskuläre Erkrankungen stellen weltweit die führende Todesursache dar, während unipolare depressive Störungen insbesondere innerhalb der Industrieländer einen beträchtlichen Anteil der gesundheitsökonomischen Last bilden. Gemeinsam ist den Erkrankungen eine hohe und auf absehbare Zeit ansteigende Prävalenz, hinzukommt ein nicht unerheblicher Anteil an internistisch-psychiatrischer Komorbidität. So entwickeln kardiologische Patienten nach einem Myokardinfarkt bspw. häufig eine depressive Störung. Während dieser Einfluss somatischer Erkrankungen auf die psychische Gesundheit ausführlich untersucht ist, gilt dies für den umgekehrten nosologischen Zusammenhang nur eingeschränkt. Fest steht, dass depressive Patienten eine gegenüber Gesunden erhöhte Sterblichkeit aufweisen, die sich nicht allein auf Suizide, sondern allen voran auf ein schlechteres kardiovaskuläres Risikoprofil zurückführen lässt. So begünstigt das Vorliegen einer depressiven Störung die Entwicklung somatischer Pathologien wie z. B. des metabolischen Syndroms, was wiederum zu einer Erhöhung der Inzidenz artherosklerotischer Erkrankungen beiträgt. Neben behavioralen und inflammatorischen Prozessen scheint dabei v. a. dem Hypothalamus-Hypophysen-Nebennierenrinden-System eine entscheidende Mediator-Rolle zuzukommen. Bei diesem handelt es sich um ein komplexes endokrines System, das hauptsächlich im Rahmen des Stresserlebens zahlreiche Auswirkungen auf den Metabolismus besitzt und darüber hinaus enge Verknüpfungen zum autonomen Nervensystem sowie dem Immunsystem aufweist. Die Evaluation der Funktion des Hypothalamus-Hypophysen-Nebennierenrinden-Systems erfolgt anhand verschiedener Methoden, die jeweils spezifische Vor- und Nachteile besitzen und in ihrer Aussagekraft nicht als äquivalent anzusehen sind. Ein Konsens bzgl. des zur Untersuchung somatischer Folgeschäden bei depressiven Patienten vorrangig einzusetzenden Verfahrens besteht bislang nicht. Dies ist insofern von wissenschaftlicher Relevanz, als dass bei Patienten mit affektiven Störungen regelmäßig und in unterschiedlichem Ausmaß eine Überaktivierung des Stress-Systems z. B. in Form eines erhöhten Sympathikotonus oder einer Hypercortisolämie vorliegt, was mit diversen somatischen Folgeschäden in Verbindung gebracht wird/werden kann. So ließen sich einige Pathologien, die bei Patienten mit Cushing-Syndrom vorliegen, auch bei depressiven Patienten finden, z. B. eine viszerale Adipositas, ein reduziertes Volumen des Hippocampus sowie eine verringerte Knochendichte. In einer Pilotstudie konnte bei depressiven Patienten, die eine Dysfunktion des Hypothalamus-Hypophysen-Nebennierenrinden-Systems in Form einer Non-Suppressionsreaktion auf den Dexamethason-Hemmtest oder eine Hypercortisolämie aufwiesen, außerdem eine im Vergleich zu gesunden Kontrollen signifikante linksventrikuläre Hypertrophie festgestellt werden, die als eigenständiger Risikofaktor hinsichtlich der kardiovaskulären Mortalität gilt. Im Rahmen der dieser Arbeit zugrundeliegenden STRESSD HEART-Studie wurde daher an 57 Patienten, die sich aufgrund einer depressiven Episode im Zentralinstitut für Seelische Gesundheit Mannheim in Behandlung befanden, die Aktivität des Hypothalamus-Hypophysen-Nebennierenrinden-Systems evaluiert und die Auswirkung einer Funktionsstörung auf die linksventrikuläre Masse untersucht. Letztere wurde dabei echokardiographisch ermittelt. Im Hinblick auf die Funktion des Stresssystems erfolgte ein Methodenvergleich zwischen Dexamethason-Hemmtest, Messung der Cortisol-Ausscheidung über den Nachturin sowie einer abendlichen Cortisol-Bestimmung im Speichel. Die Prävalenz einer linksventrikulären Hypertrophie lag bei den untersuchten Probanden mit je nach verwendetem echokardiographischen Index 12 – 37 % deutlich höher als es bei einer vergleichbaren gesunden Population zu erwarten gewesen wäre. Die Werte für die linksventrikuläre Masse bei Non-Suppressoren betrugen dabei im Mittel 207 ± 73 g gegenüber 343 ± 97 g in der Pilotstudie. Das Vorliegen einer Hypertrophie korrelierte jedoch nur eingeschränkt mit den Parametern zur Evaluation des Hypothalamus-Hypophysen-Nebennierenrinden-Systems, sodass sich ein signifikanter Unterschied nur zwischen den Gruppen der Non-Suppressoren und Suppressoren fand, jedoch nicht in Bezug auf die nächtliche Cortisol-Ausscheidung über den Urin oder die Konzentration im Speichel. Auch der Zusammenhang zwischen gestörter Reaktion auf den Dexamethason-Hemmtest und linksventrikulärer Masse erreichte nach statistischer Kontrolle für das Alter und das Geschlecht nicht mehr das Signifikanzniveau. Mit Hilfe der multiplen linearen Regressionsanalyse konnte ein eigenständiger Einfluss der Reaktion auf den Dexamethason-Suppressionstest auf die linksventrikuläre Masse dementsprechend nicht festgestellt werden. Für den Blutdruck ließ sich jedoch ein solcher Einfluss nachweisen, was auch nach Kontrolle für die Variablen Alter, Geschlecht sowie BMI Bestand hatte. Der Methodenvergleich der verschiedenen Parameter zur Evaluation des Hypothalamus-Hypophysen-Nebennierenrinden-Systems ergab insgesamt unterschiedlich starke Korrelationen. So wiesen insbesondere die Cortisol-Bestimmungen im Speichel nur eine schwache Assoziation zu den übrigen Methoden und keine Assoziation zu somatischen Parametern auf. Die nächtliche Cortisol-Ausscheidung über den Urin korrelierte hingegen stark und positiv mit dem Cortisol-Serumspiegel nach Dexamethason-Gabe und identifizierte bei einzelnen Probanden Dysfunktionen des Hypothalamus-Hypophysen-Nebennierenrinden-Systems, die im Dexamethason-Hemmtest eine unauffällige Reaktion gezeigt hatten. Zusammenfassend legen die Ergebnisse der Arbeit nahe, dass zum Zwecke einer Untersuchung des Zusammenhangs zwischen der Aktivität des Hypothalamus-Hypophysen-Nebennierenrinden-Systems und somatischen Folgeschäden eine Kombination aus DST mit anschließender Serum-Cortisol-Bestimmung und eine Messung des freien Cortisols im Nachturin erfolgen sollte, da letztere dazu geeignet zu sein scheint, einzelne Probanden mit gestörter Funktion des Hypothalamus-Hypophysen-Nebennierenrinden-Systems zu identifizieren, die im DST unerkannt bleiben. Mit Hinblick auf die Anwendung im klinischen Setting gehen diese Methoden mit spezifischen Vorteilen einher, so zeigen sich die nächtliche Urinsammlung sowie die Durchführung eines DST als Kurztest mit einmaliger Blutentnahme als günstige, gegenüber Störungen robuste und von Patienten gut akzeptierte Verfahren. Hinsichtlich des Vorliegens einer linksventrikulären Hypertrophie widersprechen die in der Arbeit vorgestellten Daten der Annahme der Pilotstudie. Zwar lag bei depressiven Patienten eine erhöhte Prävalenz für eine linksventrikuläre Hypertrophie vor, diese schien sich jedoch nur unter bestimmten Voraussetzungen zu entwickeln, sodass von einer klinisch relevanten Hypertrophie mit signifikanten Auswirkungen auf das kardiovaskuläre Risiko bei depressiven Patienten nur im Falle einer starken Dysfunktion des Hypothalamus-Hypophysen-Nebennierenrinden-Systems bei gleichzeitig vorliegender arterieller Hypertonie auszugehen sein dürfte. Diese Ergebnisse sind jedoch in Anbetracht der geringen Fallzahl der untersuchten Probanden mit Vorsicht zu betrachten.

Cushing’s Syndrome

Chapter

Mar 2022

Cushing’s syndrome (CS) results from long-standing exposure to excessive circulating levels of glucocorticoids, and can be endogenous or exogenous. The diagnosis of endogenous CS is challenging because of the similarities that the syndrome has to other clinical entities defined as pseudo-Cushing states. A step-by-step diagnosis starts from the confirmation of hypercortisolaemia followed by the localisation of the source of cortisol hypersecretion; this includes biochemical investigation along with imaging studies. Treatment focuses on the resolution of the hypercortisolaemia using an individualised approach, initially targeting the source of CS and then the extension of the disease. Meticulous evaluation has to be instituted with regard to identifying the source of hypercortisolaemia, followed by careful and continuing evaluation of the patient.KeywordsCushing’s syndromeCushing’s diseasePasireotideEctopic Cushing’s syndrome

Recombinant Histidine-Tagged Nano-protein-based Highly Sensitive Electro-Sensing Device for Salivary Cortisol

Article

Dec 2021
BIOELECTROCHEMISTRY

We have developed a powerful biosensing strategy for immobilizing histidine-tagged (His-Tag)-oriented recombinant nano-protein immobilization on a chemically modified glassy carbon electrode (GCE) surfaces via (S)-N-(5-amino-1-carboxypentyl)iminodiacetic acid (ANTA) acting as a chelating Ni²⁺ centered interaction. Here, we introduce a label-free electro-sensor to quantify cortisol levels in saliva samples for point-of-care testing (POCT). The high specificity of the chemically modified GCE was established by genetically bio-engineered metal-binding sites on the selected recombinant apoferritin (R-AFTN) nano-protein to impart functionality to its surface and by coating the carbon surface with the self-assembled monolayers of 4-aminobenzoic acid (4-ABA) attached to ANTA groups complexed with Ni²⁺ transition metal ions. Despite the variety of conventional assays available to monitor cortisol levels, they require bulky exterior outfits, which hinders use in the healthcare systems. Therefore, we performed a rapid, easy-to-implement, and low-cost quantitative electro-sensor to enable the real-time detection of cortisol levels in saliva samples. As a result, the cortisol electro-sensor fabricated with high specificity utilizing a GCE could measure cortisol levels with a detection limit of 0.95 ng/ml and sensitivity of 7.91 μA/(ng/mL), which is a practical approach in human saliva. Thus, protein nanoprobe-based cortisol biosensing showed high sensitivity and selectivity for the direct electro-sensing of cortisol for POCT.

Prolactin and Other Pituitary Disorders in Kidney Disease

Article

Mar 2021
SEMIN NEPHROL

Prolactin levels are increased in chronic kidney disease (CKD) as a result of reduced clearance and increased secretion. Hyperprolactinemia manifests as galactorrhea and hypogonadism. Treatment of hyperprolactinemia should focus on improving bothersome galactorrhea or hypogonadism by using dopamine agonists and/or replacement of sex hormone(s). Changes in the hypothalamic–pituitary–adrenal axis in CKD are characterized by increases in adrenocorticotropic hormone (ACTH) and cortisol levels, largely preserved circadian rhythms of ACTH and cortisol, and a normal response of cortisol to ACTH, metyrapone, and insulin-induced hypoglycemia. However, the hypothalamic–pituitary–adrenal axis is less inhibited by 1 mg dexamethasone but retains normal suppression by higher-dose dexamethasone. Diagnosis of adrenal insufficiency in CKD patients, as in normal subjects, usually is made by finding a subnormal cortisol response to ACTH. The mainstay of treatment of adrenal insufficiency is to replace glucocorticoid hormone. Cushing's disease in CKD is difficult to diagnose and relies on the dexamethasone suppression test and the midnight salivary cortisol test because the 24-hour urine free cortisol test is not useful because it is increased already in CKD. Treatment of Cushing's disease involves surgery, complemented by radiation and/or medical therapy if necessary. Growth hormone levels are increased and insulin-like growth factor 1 levels are normal in patients with CKD. In a normal patient with CKD, as in one with acromegaly, there can be a paradoxic increase in growth hormone after an oral glucose load. Therefore, diagnosis of acromegaly in renal insufficiency is challenging. The treatment of choice for acromegaly is surgery, although data for medical treatment for acromegaly in CKD are rare. In patients with renal impairment, arginine vasopressin levels are increased as a result of decreased clearance, and there also is impairment of arginine vasopressin signaling in renal tubules. Diabetes insipidus can be masked in advanced kidney disease until kidney transplantation. Diagnosis of the syndrome of inappropriate antidiuretic hormone is similar in mild or moderate kidney disease as in normal subjects, but is challenging in patients with advanced kidney disease owing to the impairment in urine dilution.

Cushing Disease: Diagnosis and Treatment

Chapter

Mar 2019

Pituitary corticotroph adenomas (causing Cushing disease, CD) are the most common cause of endogenous Cushing syndrome (CS) in children although their prevalence varies within age groups. The initial workup of a patient suspected to have CS involves the demonstration of hypercortisolemia and/or excess urinary free cortisol excretion, the loss of the normal circadian rhythm of cortisol production, and the lack of suppression of cortisol secretion after low-dose dexamethasone suppression test. The identification of the source of CS involves the measurement of the morning corticotropin (ACTH) levels, imaging studies (pituitary magnetic resonance imaging and adrenal gland computed tomography), and other tests, including high-dose dexamethasone suppression and corticotropin-releasing hormone (CRH) stimulation. The first-line management of CD is the transsphenoidal (TSS) resection of the pituitary adenoma. In cases where TSS fails, radiation and/or medical therapy and medical or surgical (bilateral) adrenalectomy may eventually lead to control of the hypercortisolemia.

Other Pituitary Disorders and Kidney Disease: Diagnosis and Treatment

Chapter

Jan 2019

Prolactin (PRL) levels are elevated in chronic kidney disease (CKD) due to reduced clearance and increased secretion. Hyperprolactinemia manifests as galactorrhea and hypogonadism. Treatment of hyperprolactinemia should focus on improving bothersome galactorrhea or hypogonadism by using dopamine agonists and replacement of sex hormone(s). Changes in the hypothalamic-pituitary-adrenal (HPA) axis in CKD are characterized by increases in adrenocorticotropic hormone (ACTH) and sometimes cortisol levels, largely preserved circadian rhythms of ACTH and cortisol, and a normal response of cortisol to ACTH, metyrapone, and insulin-induced hypoglycemia. However, the HPA axis is less inhibited by 1 mg of dexamethasone but retains normal suppression by higher-dose dexamethasone. Diagnosis of adrenal insufficiency in CKD patients, as in normal subjects, is usually made by finding a subnormal cortisol response to ACTH. The mainstay of treatment of adrenal insufficiency is to replace glucocorticoid hormone. Cushing’s disease in CKD is difficult to diagnose and relies on the dexamethasone suppression test and the midnight salivary cortisol test since 24-h urine-free cortisol test is not useful. Treatment of Cushing’s disease involves surgery, complemented by radiation and/or medical therapy if necessary. In CKD, arginine vasopressin (AVP) levels are elevated due to decreased clearance, and there is also impairment of AVP signaling in renal tubules. Diabetes insipidus can be masked in advanced kidney disease until kidney transplantation. Diagnosis of syndrome of inappropriate antidiuretic hormone is similar in mild or moderate kidney disease as in normal subjects but is challenging in those with advanced kidney disease owing to the impairment in urine dilution.

Competitive Immunoassays for the Detection of Small Molecules Using Single Molecule Arrays

Article

Nov 2018

Small molecule detection is important for many applications including clinical diagnostics, drug discovery, and measurements of environmental samples and agricultural products. Current techniques for small molecule detection suffer from various limitations including low analytical sensitivity and complex sample processing. Furthermore, due to their small size, small molecules are difficult to detect using an antibody pair in a traditional sandwich assay format. To overcome these limitations, we developed an ultra-sensitive competitive immunoassay for small molecule detection using Single Molecule Arrays (Simoa). We show that the competitive Simoa assay is approximately 50-fold more sensitive than the conventional ELISA. We performed theoretical calculations to determine the factors that influence the sensitivity of competitive Simoa assays and used them to achieve maximal sensitivity. We also demonstrate detection of small molecules in complex biological samples. We show that the competitive Simoa assay is a simple, fast, and highly sensitive approach for ultra-sensitive detection of small molecules.

The diagnosis of hypercortisolism, biochemical criteria differentiating patients from lean and obese normal subjects and from females on oral contraceptives

Article

Jan 1969

Advances in the diagnosis and treatment of Cushing's syndrome

Article

May 1995
Bailliere Clin Endocrinol Metabol

Excess endogenous glucocorticoid production, whether ACTH-dependent or ACTH-independent, results in the classic clinical and biochemical picture of Cushing's syndrome. The diagnosis requires demonstration of an increased cortisol secretion rate, best achieved using determination of urinary free cortisol as an index. In mild cases, distinction from the hypercortisolism of pseudo-Cushing states may prove difficult. If the physician is in doubt, a dexamethasone/CRH test should be performed. Primary adrenal Cushing's syndrome can be diagnosed on the basis of undetectable plasma ACTH and the results of adrenal imaging procedures. ACTH-dependent Cushing's syndrome can be differentiated using an oCRH test and imaging procedures. In the presence of a discrete pituitary lesion on imaging, a standard oCRH test with results consistent with such a lesion is sufficient to proceed to transsphenoidal surgery. In the absence of such a lesion or if the oCRH test is equivocal, simultaneous BIPSS with oCRH administration should be performed to distinguish between a pituitary or ectopic source.Surgical ablation is the treatment of choice for all types of Cushing's syndrome. In the 5% of cases with Cushing's disease in whom transsphenoidal surgery fails and in the 5% of cases in whom the disease recurs, repeat transsphenoidal surgery or radiation therapy in association with mitotane treatment are reasonable alternatives. Bilateral adrenalectomy effectively cures hypercortisolism if resection of the ACTH-secreting tumour is unsuccessful and radiation/medical therapy fails.

6 beta-Hydroxycortisol excretion in hypercortisolemic states.

Article

Apr 1979

Urinary 6beta-hydroxycortisol (6betaOHF) excretion was measured and compared with free cortisol and 17-hydroxycorticosteroid (17OH) excretion in normal children, patients with Cushing's syndrome or disease (CSD), and patients during cortisol therapy. Normal 6betaOHF excretion in children was 0.23 +/- 0.03 mg/m2/24 h (mean +/- SE). No sex difference was found. ACTH infusion (40 U/day for 5 days) and high dose cortisol altered the 6 betaOHF:17OH ratio so that it was indistinguishable from the ratio seen in CSD. The fact that both Cushing's disease and high dose cortisol therapy caused the same change in the 6 betaOHF:17OH ratio suggests that cortisol and not ACTH induced 6beta-hydroxylase in hypercortisolemic subjects. Since the 6betaOHF:17OH ratio in CSD patients was always well above the normal range, measurement of 6betaOHF excretion was a better and more rapid test for chronic hypercortisolemia than urinary 17OH or free cortisol. Thus, measurement of urinary 6betaOHF is suggested as a good diagnostic test for hypercortisolemic states.

Urinary free corticosteroid excretion and renal function

Article

Aug 1978

Theoretically urinary free corticosteroid excretion should be affected by renal function and this would make it a less sensitive index of hypercortisolaemia. In 28 consecutive urine samples there was a clear relationship (r = 0.83; P less than 0.001) over a range of creatinine clearances 0.3-200 ml/min. Although an allowance could be made for renal function this would not necessarily improve the discrimination of normal from abnormal. Until data comparing corrected to uncorrected urinary free corticosteroid excretion become available, we recommend a short dexamethasone test as the initial investigation in patients with suspected hypercortisolaemia and abnormal plasma creatinine concentrations.

Screening tests for Cushing's syndrome

Article

Jan 1991

Uraemia and adrenocortical function in Nigerian subjects

Article

Apr 1990
Afr J Med Med Sci

In assessing the pituitary-adrenal axis of uraemic Nigerians, we investigated the circadian rhythm of plasma cortisol secretion, the response to the overnight dexamethasone (1 mg) suppression test and the pattern of excretion of urinary free cortisol (UFC) in 10 uraemic subjects and nine non-uraemic controls. Basal (0800 h) plasma cortisol levels were similar in both uraemic (mean +/- s.e.m.; 224 +/- 36 nmol/l) and non-uraemic (218 +/- 47 nmol/l) subjects. The non-uraemic subjects demonstrated the normal late night (2300 h) reduction in cortisol levels but this was absent in uraemic subjects in whom the basal and late night values were similar. Post-dexamethasone (0800 h) values were suppressed by 80% in non-uraemic subjects (P less than 0.01) from 218 +/- 47 nmol/l (at 2300 h) to 44 +/- 16 nmol/l (at 0800 h), whereas there was lack of suppression (P greater than 0.05) in values from uraemic subjects (224 +/- 36 nmol/l at 2300 h and 210 +/- 39 nmol/l at 0800 h). Irrespective of the degree of renal impairment in uraemic subjects, the 24 h UFC excretion was significantly greater (P less than 0.05) (1126 +/- 403 nmol/24 h) compared with non-uraemic subjects (342 +/- 94 nmol/24 h). These results confirm previous observations in Caucasians and reaffirm the existence of a pseudo-Cushingoid state in uraemia which may contribute to the associated hypertension and electrolyte abnormalities.

Measurement of urinary free 20 alpha-dihydrocortisol in biochemical diagnosis of chronic hypercorticoidism

Article

Jun 1986

Using liquid chromatography, we estimated the urinary excretion of 20 alpha-dihydrocortisol (20-DH) and urinary free cortisol (UFC) in normal subjects and in 40 patients with Cushing's syndrome of different etiologies. The median normal excretion rate (nmol/24 h) was 174 for 20-DH and 68 for UFC, the 20-DH/UFC ratio thus being 2.55. For patients with Cushing's syndrome, the excretion rate was 1798 for 20-DH and 298 for UFC, the ratio 6.03. We evaluated the effect of acute stimulation of adrenal secretion on 20-DH and UFC by administering corticotropin to six normal subjects. After such stimulation, the excretion rate was 566 for 20-DH and 1238 for UFC (ratio 0.45). Whereas 20-DH excretion rate exceeded the normal range in all patients, six patients had normal or even below-normal values for UFC excretion. Evidently, measurement of urinary 20-DH is a better test for chronic hypercorticoidism than is measurement of urinary UFC, and chronic hypercorticoidism can be differentiated from the acute state by the 20-DH/UFC ratio.

Clinical evaluation of urinary cortisol determinations by competetive protein-binding radioassay.

Article

Apr 1968

B E Murphy

Prolonged serum half-life of Cortisol in renal failure

Article

Mar 1973
Johns Hopkins Med J

Serum cortisol concentrations and half life (t 1/2) were determined in 10 subjects on 14 occasions. The groups were: Group A, patients with renal disease and serum creatinine above 7 mg/100 ml, studied prior to hemodialysis, and Group B, renal patients with serum creatinine less than 7 mg/100 ml studied immediately following hemodialysis, and normal subjects. Serum t 1/2 was found to be prolonged in Group A, although there was no difference in serum cortisol levels. In one subject, studied both before and after dialysis, the expected fall in serum creatinine was associated with a decreased t 1/2 of serum cortisol, but no change in serum cortisol concentration.

Cushing's syndrome. An evaluation of the clinical usefulness of urinary free cortisol and other urinary steroid measurements in diagnosis

Article

Feb 1973
QJM

Urinary free cortisol excretion has been measured in a group of 40 patients with Cushing's syndrome and in 34 patients in whom this diagnosis was suspected on clinical grounds, but in whom it was later disproved. Measurements were made in the basal state, during dexamethasone suppression, and after metyrapone (when free cortisol and 11-deoxycortisol were measured together) and the results compared with those of 17 oxogenic steroid measurements. In the basal state no normal or ‘suspected’ patient excreted more than 106 μg/24 h of free cortisol while the lowest value seen in any patient with Cushing's syndrome was 110 μg/24 h. In 25 per cent of the patients with hyperadrenalism 17 OGS excretion was within the normal range. Three patients with ectopic ACTH produc tion all excreted more than 1000 μg of free cortisol in 24 h and in two of the three 17 OGS excretion was greater than 100 mg/ h. During low-dose dexamethasone suppression (2 mg daily) free cortisol excretion fell to very low levels in normal and suspected subjects but failed to do so in patients with Cushing's syndrome, although a few patients did show suppression almost to within the normal range. In no patient with Cushing's syndrome did 17 OGS excretion fall to less than 5 mg/24 h. However, it also failed to do this in 43 per cent of the ‘suspected’ subjects. High-dose dexamethasone suppression (8 mg/day) failed to provide a clear differentiation between patients with pituitary-dependent disease and those with autonomous adrenal lesions or ACTH-producing tumours in terms of change in either free cortisol or 17 OGS excretion. On metyrapone testing 96 per cent of pituitary-dependent patients showed a definite rise in 17 OGS excretion. We have not yet seen such a response in a patient with a non-pituitary-dependent lesion. Measurement of free F+S excretion was not