Clinical characterization of patients with macroprolactinemia and monomeric hyperprolactinemia

Macroprolactinemia is often a cause of misdiagnosis, unnecessary expensive investigation, and unsuitable treatment. The aim of the present study was to investigate the clinical findings and the concentrations of macroprolactin in patients with hyperprolactinemia in our region. Eighty-four female hyperprolactinemic patients were screened for macroprolactinemia. Prolactin was measured by chemiluminescence method on an Immulite 2000 analyzer (Siemens Health Diagnostics, Deerfield, IL, USA). Recoveries less than or equal to 40% after polyethylene glycol precipitation were indicative of macroprolactinemia. Clinical features and biochemical values were compared in true hyperprolactinemic and macroprolactinemic patients. Macroprolactinemia was detected in 31 patients (36.9%), with 84 hyperprolactinemic female patients. There was no difference in frequency of galactorrhea and oligomenorrhea/amenorrhea between the two groups. When we evaluated the clinical features of patients according to prolactin levels, no significant difference was found between the groups. In conclusion, our initial data show that no clinical features could reliably differentiate macroprolactinemic from true hyperprolactinemic patients, but at least one of these symptoms was present in most macroprolactinemic patients.