Article

Falsely low serum prolactin in two cases of invasive macroprolactinoma.

Department of Clinical Endocrinology, Hannover Medical School, 30623 Hannover, Germany.
Pituitary (Impact Factor: 2.22). 02/2002; 5(4):261-5. DOI: 10.1023/A:1025334001748
Source: PubMed

ABSTRACT The differential diagnosis of tumors at the base of the skull comprises meningiomas, neurinomas, gliomas, metastatic carcinomas, chordomas, epidermoids, and pituitary adenomas. About half of the pituitary adenomas are prolactinomas which are unique in a sense that medical therapy causes rapid tumor shrinkage and symptomatic improvement. We report on two patients in which the diagnosis of an invasive macroprolactinoma was masked by apparently low prolactin levels caused by a high-dose hook effect in the chemiluminometric assay. The first case a 49 year old male with impairment of hearing on the left side was presented in the Department of Otorhinolaryngology. A massive invasively growing tumor was demonstrated on a cranial MRI. Endocrine tests revealed normal pituitary function and normoprolactinemia. The patient underwent debulking surgery, occipitocervical fusion because of destruction of the first cervical vertebra and subsequent irradiation. The histopathological diagnosis was invasive prolactinoma. A repeat prolactin (PRL) sample, which was assayed using serial dilutions, revealed a real PRL level of 89,700 ng/ml. Dopamine agonist therapy was initiated under which PRL levels declined in parallel with tumor size. The second case a 40 year old male was presented with acute visual loss. Cranial MRI showed a large tumor at the base of the skull. Based on a transnasal biopsy, the preliminary diagnosis was a poorly differentiated carcinoma for which emergency irradiation was performed. Endocrine tests demonstrated partial hypopituitarism and moderate hyperprolactinemia. Hydrocortisone was substituted and dopamine agonist therapy was started because of moderate hyperprolactinemia. The final histopathological diagnosis was invasive prolactinoma. A repeat PRL sample assayed in serial dilution demonstrated an apparent rise in PRL with a maximum value of 6,460 ng/ml. Under dopamine agonist therapy, PRL declined to normal values, tumor size decreased and cranial nerve palsies disappeared. The apparently falsely low prolactin levels in the initial work-up of both patients were caused by a high-dose hook effect in the PRL assay. Serial dilutions of serum PRL samples is, therefore, mandatory in the diagnostic work-up of patients with large invasive tumors at the base of the skull. This avoids unnecessary aggressive and dangerous treatment like surgery or radiotherapy in cases where pharmacological treatment may be the choice.

0 Followers
 · 
103 Views
  • Source
    • "When clinical and imaging evidence indicates the presence of a large pituitary tumor and PRL levels are low, serial dilutions can reveal very high levels. The falsely low levels are caused by an effect in the assay known as the high-dose hook effect (an extremely large amount of PRL prevents accurate assessment by the antibody in the assay) (Schofl, et al; 2002). "
    Basic Gynecology - Some Related Issues, 02/2012; , ISBN: 978-953-51-0166-6
  • Source
    • "When clinical and imaging evidence indicates the presence of a large pituitary tumor and PRL levels are low, serial dilutions can reveal very high levels. The falsely low levels are caused by an effect in the assay known as the high-dose hook effect (an extremely large amount of PRL prevents accurate assessment by the antibody in the assay) (Schofl, et al; 2002). "
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Hintergrund: An der Betreuung von Patienten mit endokrin aktiven Hypophysenadenomen sind aufgrund der Komplexitt der Erkrankung die Fachdisziplinen der Endokrinologie, Neurochirurgie, Neuroradiologie und Strahlentherapie beteiligt. Diese Disziplinen werden am Universittsklinikum Leipzig im Rahmen einer gemeinsamen Hypophysensprechstunde durch integrierte Diagnostik- und Therapiekonzepte verzahnt. Dieses Vorgehen wird seit nunmehr 6 Jahren bei Patienten mit hormoninaktiven und hormonaktiven Tumoren eingesetzt. Methodik: Neben der Beschreibung der interdisziplinren Zusammenarbeit wird in dieser Arbeit ber die Ergebnisse bei Patienten mit STH-(somatotropes Hormon-)produzierenden Adenomen und Prolaktinomen berichtet. Ergebnisse: Bei Patienten mit STH-produzierenden Adenomen konnte in 80% (Mikroadenome) bzw. 40% (Makroadenome) eine Remission erreicht werden. Bei den Patienten mit Prolaktinomen lie sich abhngig von der Adenomgre in 75–100% eine Normalisierung des Prolaktins erzielen. Von den wenigen neurochirurgisch versorgten Patienten mit Prolaktinom konnten 50% (2/4) geheilt werden. Schlussfolgerung: Die Betreuung von Patienten mit hormonaktiven Hypophysenlsionen in einem interdisziplinren Therapiekonzept verbessert die Behandlungsqualitt und ermglicht eine schnelle und fachbergreifende Abstimmung der Therapiekonzepte. Background: Treatment of patients with pituitary adenomas is complex and involves several medical specialties. At the Medical Center of the University of Leipzig, Germany, an interdisciplinary pituitary outpatient care unit has been established for 6 years. Methods: The interdisciplinary collaboration and the outcome of patients with growth hormone-(GH-) and prolactin-secreting pituitary adenomas are described. Moreover, therapeutic strategies for patients with hormonally active pituitary adenomas are presented and discussed. Results: In patients suffering from GH-producing adenomas, a remission could be achieved in 80% (microadenomas) and 40% (macroadenomas) of the cases, respectively. This is comparable to major published studies. Furthermore, prolactinomas decreased in size during treatment in at least 75% of all cases depending on the initial size of the lesion which is also comparable to data from other groups. Conclusion: Taken together, an interdisciplinary approach improves outcome and quality of care of patients with hormonally active pituitary adenomas.
    03/2005; 100(4):173-179. DOI:10.1007/s00063-005-1018-0
Show more