IGF-1 levels may increase paradoxically with dopamine agonist treatment for prolactinomas.

OBJECTIVE: Hyperprolactinemia is common in acromegaly and in these patients, insulin-like growth factor (IGF)-1 level may decrease with dopamine agonist. We report a series of patients with prolactinoma and a paradoxical increase of IGF-1 levels during cabergoline treatment. METHODS: Clinical characteristics and response to treatment of patients with prolactinomas, in whom normal or slightly elevated baseline IGF-1 levels increased with cabergoline. RESULTS: The cohort consisted of ten prolactinoma patients (nine males, mean age 48 ± 14 years). Mean adenoma size was 23.8 ± 16.2 mm, with cavernous sinus invasion in eight. In five patients baseline IGF-1 levels were normal and in four levels were 1.2-1.5-fold the upper limit of the normal (ULN). One patient had IGF-1 measured shortly after initiating cabergoline and it was 1.4 × ULN. During cabergoline treatment (dose range 0.5-2 mg/week) PRL normalization was achieved in all and tumor shrinkage occurred in seven patients. The mean IGF-1 increase on cabergoline was 1.7 ± 0.4 × ULN. Cabergoline dose reduction or interruption was attempted in five patients and resulted in decreased IGF-1 levels in all, including normalization in two patients. Three patients were eventually diagnosed with acromegaly, one was referred for pituitary surgery followed by complete remission, another patient was switched to somatostatin analogue, and the third was treated by combination of somatostatin analogues with pegvisomant, with reduction of IGF-1 in all these patients. CONCLUSION: IGF-1 levels may increase to clinically significant levels during cabergoline treatment for PRL-adenoma. We suggest IGF-1 monitoring in all patients treated with dopamine agonists and not only in those presenting symptoms of acromegaly.

Pituitary imaging findings in male patients with hypogonadotrophic hypogonadism.

CONTEXT: Data on pituitary imaging in adult male patients presenting with hypogonadotrophic hypogonadism (HH) and no known pituitary disease are scarce. OBJECTIVE: To assess the usefulness of pituitary imaging in the evaluation of men presenting with HH after excluding known pituitary disorders and hyperprolactinemia. DESIGN: A historical prospective cohort of males with HH. PATIENTS: Men who presented for endocrine evaluation from 2011 to 2014 with testosterone levels <10.4 nmol/L (300 ng/mL), normal LH and FSH levels and no known pituitary disease. RESULTS: Seventy-five men were included in the analysis. Their mean age and BMI were 53.4 ± 14.8 years and 30.7 ± 5.2 kg/m2, respectively. Mean total testosterone, LH, and FSH were 6.2 ± 1.7 nmol/L, 3.4 ± 2 and 4.7 ± 3.1 mIU/L, respectively. Prolactin level within the normal range was obtained in all men (mean 161 ± 61, range 41-347 mIU/L). Sixty-two men had pituitary MRI and 13 performed CT. In 61 (81.3%) men pituitary imaging was normal. Microadenoma was found in 8 (10.7%), empty sella and thickened pituitary stalk in one patient (1.3%) each. In other four patients (5.3%) a small or mildly asymmetric pituitary gland was noted. No correlation was found between testosterone level and the presence of pituitary anomalies. CONCLUSIONS: This study suggests that the use of routine hypothalamic-pituitary imaging in the evaluation of IHH, in the absence of clinical characteristics of other hormonal loss or sellar compression symptoms, will not increase the diagnostic yield of sellar structural abnormalities over that reported in the general population.