Endocrine Abstracts

Introduction: Prolactin (PRL) levels > 250 ng/ml are highly suggestive of prolactinomas though they may be also seen in other conditions, particularly macroprolactinemia, GH and PRL cosecreting tumors, and renal failure. Drug-induced hyperprolactinemia is typically associated with mild PRL elevation (usually <100 ng/ml). Higher levels (around 300 ng/ml) have been occasionally reported, particularly with risperidone, an atypical antipsychotic drug.

Case report: A 25 year old asymptomatic women was referred to the endocrinologist with the diagnosis of a microprolactinoma. In a routine lab evaluation, PRL levels of 720 ng/ml (15120 mIU/l) e 690 ng/ml (14490 mIU/l) were found (normal range, 2.8–29.2 ng/ml [59–613 mIU/l]). A 0.5 cm pituitary lesion was subsequently shown on a MRI scan. Macroprolactin screening was negative. Thyroid and renal functions were normal. The physical examination do not identify noteworthy findings. The patient has been treated with a combined oral contraceptive pill for 24 months and with domperidone (a prokinetic drug) over the past 3 months (in the treatment of functional dyspepsia). Two months after domperidone withdrawal, PRL levels dropped to 18 ng/ml (328 mIU/l).

Conclusion: This case shows that domperidone should be included in the list of drugs that may be associated with very high PRL levels. The lesion depicted on MRI scan was a nonfunctional pituitary microadenoma.