Diagnosis of hyperprolactinemia by single serum prolactin determination: Challenges and recommendations

Secretion of prolactin follows a circadian rhythm of secretion, and several factors play an important role in the regulation of its secretion. An accurate diagnostic evaluation is essential for the proper management of the patient, which can be accomplished through a narrow observation and critical analysis of all the prolactin results which are above the standard upper limit of normal. If the circulating prolactin level exceeds five times the upper normal limit, a single test is sufficient to diagnose hyperprolactinemia. However, mildly elevated (20–40 ng/ml) results should be confirmed with at least two tests to counteract the circadian fluctuation or other factors causing transitory elevation. Repeat analysis of circulating prolactin on a later date preferably with 2–3 samples collected at few min interval is also recommended to minimize the effect of pulsatility when the elevation of serum PRL is doubtful (may be due to venipuncture induced stress) or when results are inconsistent with the clinical features. This review article presents an overview of the biological and analytical aspects of prolactin along with the impact of stress on prolactin secretion, as well as the current approach employed to tackle the chances of misdiagnosis and overtreatment. However, to understand the exact mechanism of stress induced hyperprolactinemia and its implications, further research is required.