Macroprolactinemia in Patients Presenting With Stalk Compressing Masses

Abstract

Introduction Decreased dopaminergic inhibition of prolactin secretion by hypothalamus or stalk compressive masses can induce hyperprolactinemia. Macroprolactin may be the dominant form of prolactin in any case of hyperprolactinemia. The aim of this study was to evaluate the association of macroprolactinemia in patients presenting with hyperprolactinemia caused by stalk compressive masses. Patients and Methods We evaluated a series of 37 patients with hyperprolactinemia because of hypothalamus or stalk compressive masses. In patients with significant hyperprolactinemia (>35 μg/L in women and >30 μg/L in men), serum prolactin measured again, after incubation with poly ethylene glycol (PEG). Macroprolactinemia was diagnosed if the serum prolactin after PEG was ≤40% of initial serum prolactin. In 2 patients with macroprolactinemia, prolactin measured again before and after PEG, 2 months after surgery. Results Serum prolactin was significantly high in 18 (48.6%) patients. Macroprolactinemia proved in 3 patients (8.1%) after PEG incubation. In 2 of 3 patients surgery was performed. Prolactin level decreased after surgery in them but not to normal levels. After PEG test macroprolactinemia persisted but monomeric prolactin decreased to normal level only in 1 patient with complete resection, but remained elevated in the second one with significant remnant. Conclusions Macroprolactinemia may be the cause of hyperprolactinemia in stalk compressive masses. Macroprolactin forms after production and release of monomeric form from the pituitary.