[Diagnosis of hyperprolactinemia: determination of prolactin level at rest]

We present 3 women who were referred for evaluation of stress-related mild-to-moderate hyperprolactinemia. This frequent finding may mistakenly be considered a clinical problem, and lead to inappropriate investigation and therapy. We emphasize the importance of serial blood sampling for prolactin determination. We collected blood samples repeatedly under resting conditions from an indwelling venous brachial catheter, every 30 minutes for a total of 6 samples. All 3 patients had normal prolactin levels 30-60 minutes after starting the test. Neither further investigation nor medical therapy were needed and these anxious patients were reassured that their hyperprolactinemia was factitious.