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An unusual case of hyperkalaemia in infancy: question
Mireille Formosa & Nicholas J. Webb & Mohan Shenoy
Received: 7 June 2010 /Revised: 10 September 2010 /Accepted: 24 September 2010 /Published online: 6 November 2010
# IPNA 2010
A male infant presented with recurrent episodes of hyper-
kalaemia and acidosis since birth. He was born by normal
vaginal delivery at term weighing 2.7 kg (9th centile) with a
head circumference of 33 cm (9th centile) to a mother with
a known history of alcohol abuse. There were no perinatal
problems. Mother’s antenatal ultrasound scan at 20 weeks’
gestation did not identify any foetal abnormalities.
At 1 month of age, the boy was admitted to the local
hospital with a week’s history of “funny spells”, where he
had extensor posturing of his trunk and limbs and cried out.
These lasted for 2–3 min at a time. There was no apparent
relationship to feeding or passing bowel motions. On
examination, the child was noted to be thriving, with a
weight of 3.29 kg (2nd centile), a head circumference of
36 cm (9th centile) and a length of 52 cm (9th centile).
Blood pressure was 78/52 mmHg. Clinical examination
was unremarkable. He was not dehydrated on clinical
assessment. The external genitalia appeared normal.
Initial blood investigations (performed by venipuncture)
showed serum potassium 7 mmol/l, sodium 135 mmol/l,
chloride 112 mmol/l, bicarbonate 19 mmol/l, urea 2.1 mmol/
l and creatinine 26 μmol/l. The complete blood count
showed normal haemoglobin, white blood cell and platelet
values. Liver function tests were within normal limits.
Calcium, phosphate and magnesium were within the normal
range. Glucose was 4.2 mmol/l. Serum ammonia, lactate and
creatinine kinase were normal. Capillary blood gas showed a
mild metabolic acidosis with a base deficit of −5.2.
A working diagnosis of sepsis was originally consid-
ered, and he was treated with antibiotics intravenously.
A complete septic screen was negative. Cerebrospinal
fluid (CSF) lactate, plasma and CSF amino acids;
random cortisol; thyroid function tests; and 17-
hydroxyprogesterone were all within the normal range.
Serum aldosterone was entirely normal for age at
454 pmol/l (normal 300–1,500 pmol/l). Plasma renin
activity was low at <0.2 nmol/l per hour (normal 1.1–
2.7 nmol/l per hour). Urinary potassium was 10 mmol/l,
urine osmolality 151 mmol/l and plasma osmolality
290 mmol/l. Urinary screen for drugs and toxins was
negative. An ultrasound scan of the renal tract demon-
strated two normal kidneys with no evidence of hydro-
nephrosis or hydroureter.
The child had a trial of sodium bicarbonate, fludro-
cortisone and calcium resonium at 2 months of age.
However, these were not sufficient to correct the hyper-
kalaemia, which at this stage was associated with poor
weight gain (3.7 kg, 0.4th centile). He was then
commenced on low-potassium-containing milk. This
corrected the hyperkalaemia. He was discharged home
with serum potassium 3.8 mmol/l, sodium 139 mmol/l,
chloride 100 mmol/l, urea 1.2 mmol/l and creatinine
1. What is the differential diagnosis of hyperkalaemia in
2.What are the causes of end-organ resistance to
3. What is the most likely diagnosis?
The answer to this question can be found at http://dx.doi.org/10.1007/
M. Formosa:N. J. Webb:M. Shenoy (*)
Department of Paediatric Nephrology,
Royal Manchester Children’s Hospital,
Manchester M13 9WL, United Kingdom
Pediatr Nephrol (2011) 26:1065