Review: Human Prolactin ‐ Recent Advances in Physiology and Therapy

Summary: Human prolactin has been proven to exist as a unique hormone of the anterior pituitary gland. Use of sensitive bioassay and radioimmunoassay techniques has enabled it to be measured in serum and amniotic fluid. Serum prolactin values increase in some women during the luteal phase of the menstrual cycle, in all women during pregnancy and during postpartum suckling. High concentrations of this hormone are also found in amniotic fluid and in neonates for the first few weeks of life. Unlike most other pituitary hormones, prolactin is normally under inhibitory control from the hypothalamus and various stimulatory and inhibitory tests have been used to test the integrity of this hypo‐thalamic‐pituitary axis. Such tests have been used in clinical conditions where abnormally high serum prolactin levels, or hyperprolactinaemia, have been found in an attempt to localize the disorder and explain its pathogenesis. Hyperprolactinaemia is common in secondary amenorrhoea and galactorrhoea, or inappropriate lactation, and should be excluded in all patients presenting with these problems. It also occurs frequently in patients with pituitary tumours and may cause the reduced libido and impotence in some men complaining of infertility. Drug therapy is now available to suppress serum prolactin concentrations and has been used successfully to prevent or suppress puerperal lactation. Pathological states, such as hyperprolactinaemic secondary amenorrhoea and galactorrhoea have also been treated with these drugs with lowering of serum prolactin values to the normal range and subsequent restoration of ovulation and fertility, or cessation of lactation. A policy for the diagnosis, investigation and clinical management of such patients is presented.