Endocrine Abstracts

Background: It is known women suffer from macroprolactinaemia more frequently than men. Often men with unclear genesis of hyperprolactinaemia have normal or a little depressed Testosterone level. High macroprolactin level in blood serum can explain this type of hyperprolactinaemia.

Materials and methods: Sixty-four men with hyperprolactinaemia (Prl >600 mU/l) were studied. Clinical, biochemical and MRI methods were used. Prl and Testosterone levels were determined by fluorescence method. MonPrl was determined by PEG-precipitation (Delfia; Finland). Macroprolactin level was calculated from Prl and monPrl data. After investigation of 35 healthy men with normoprolactinaemia reference value were estimated: 74–390 mU/l. A recovery of macroprolactin more than 60% was accepted as macroprolactinaemia.

Results: Macroprolactinaemia was founded in 11 (I group) of 64 cases (17.1%). True hyperprolactinaemia was founded in 53 (II group) of 64 cases. All patients of II group have been taken cabergoline (median of dose – 2.5 mg/week). Median of Prl level in I group was 2356 mU/l. Median of Testosterone level was 10.4 nmol/l. The microadenomas were revealed in 3 men, macroadenomas – in 6 patients. Clinical symptoms (libido impairment, reduced sexual potency) were founded in 9 men, they all had increased monPrl level (978 mU/l). That is why all of these patients have been taken cabergoline treatment (Median dose-1.25 mg/week). In 2 patients from I group monPrl level was normal and dynamic control carried out. After 6 months median of Prl level was 689 nU/l, testosterone level-14.1 nmol/l. There were no clinical symptoms in all 9 men. monPrl level was normal in all patients (median-265 mU/l). Positive dynamics of the tumors volume was noted in 5 patients with macroadenomas (from 2.5 to 1.9 cm³) and in 2 patients with microadenomas (from 0.9 to 0.5 cm³).

Conclusions: This investigation revealed that macroprolactinaemia is founded in 17.1% in men with tumorous and not tumorous hyperprolactinaemia. MonPrl level was higher than reference value in 9 of 11 patients with macroprolactinaemia and they were treated by cabergoline. But cabergoline dose in I group was greatly lower than in II group. Therefore efficiency estimation should be determined on monPrl level, not on Prl level.