Ten-year clinical follow-up of a cohort of 51 patients with macroprolactinemia establishes it as a benign variant.

Context: Macroprolactinemia is a common finding in patients with hyperprolactinemia. There are no published long-term follow-up studies.
Objective: The aim of this study was to describe findings after prolonged follow-up in a previously published cohort of patients with macroprolactinemia.
Study Population: We studied 51 patients identified as having macroprolactinemia after polyethylene glycol precipitation.
Design: Clinical assessment and serum prolactin assay were repeated in 51 patients with macroprolactinemia after a median follow-up of 9.9 yr (range, 9-11 yr).
Results: Median age at presentation was 41 yr (range, 18-55 yr). Mean serum prolactin concentration at presentation was 1885 mU/liter, and after follow-up 1370 mU/liter. At follow-up, headache had been experienced in 12 patients (24%) and oligomenorrhea in five (10%). Galactorrhea was present in only two patients (4%). No visual deterioration was noted in 50 patients. One had a transient bitemporal hemianopia. No patients developed an autoimmune condition. Microadenoma had been identified in four patients at presentation with no new pituitary imaging abnormalities identified at follow-up.
Conclusions: During prolonged follow-up, no symptomatic progression was noted in any of our patients. This study suggests that patients with macroprolactinemia and normal concentrations of monomeric prolactin can be reassured, and extended endocrine review of such patients is not required.