Asymptomatic Hyperprolactinemia Resulting from Macroprolactinemia

The document reports on five patients who exhibited moderate hyperprolactinemia according to radioimmunoassay (RIA) measurements but did not show any clinical symptoms typically associated with hyperprolactinemia, such as galactorrhea or menstrual irregularities. These patients were found to have macroprolactinemia, a condition where larger molecular forms of prolactin with low biological activity are present, which can lead to elevated serum prolactin levels detected by RIA without accompanying symptoms. The study suggests that in such cases, further investigation or therapy for hyperprolactinemia may not be necessary. The presence of macroprolactinemia was confirmed using a column method that separates proteins based on molecular size, revealing two peaks of larger proteins in the patients' serum, except for one patient who did not have the middle peak. The document emphasizes the importance of correlating biochemical results with clinical presentation and suggests that patients with macroprolactinemia should be clinically monitored, although no long-term problems from the condition have been reported. The study also notes that macroprolactinemia may be familial.