Elevated prolactin levels in a general medicine practice invariably raise the suspicion of prolactinoma. Prolactinoma is, a benign adenoma or tumor of the pituitary gland often producing clinically significant levels of prolactin. The finding of elevated prolactin levels is therefore associated with distinct clinical and therapeutic implications. However antipsychotic medications are a major cause of hyperprolactinemia and recognition of this fact may obviate complicated and expensive testing in these patients.

To evaluate the cause of hyperprolactinemia in patients seen in a general medicine practice.

To document the role played by anti-psychotic medications in hyperprolactinemia.

We identified 364 consecutive office patients who had their prolactin levels routinely measured during an 8 month period. None of these patients were pregnant or lactating. Testing was done by a commercial laboratory and normal levels were defined as 4.0 ng/ml to 15.2 ng/ml.

Of 364 patients (203(56%) males, 161 (44%)females [ages 26 to 82]), 84 (23%) had elevated prolactin levels. Of these 55(65%) were in patients who were on antipsychotic medications. 29(35%) patients had non-psychiatric cause of hyperprolactinemia.

Prolactin levels are normally elevated during pregnancy and lactation. Elevated prolactin levels are also seen in many medical conditions including prolactinoma and primary hypothyroidism. Levels may also be elevated with the use of SSRI and SNRI medications and during times of extreme emotional stress. This study shows that the vast majority of patients seen in an general medicine practice with elevated prolactin levels have mental illnesses and are on anti-psychotic medications.