Prolactin (PRL) Test Interpretation


Prolactin (PRL) is a protein secreted from the pituitary gland. Its most well-known role in humans is enabling women to produce lactation (breast milk production). Prolactin plays an essential role in metabolism, regulation of the immune system and pancreatic development.



This test measures the amount of prolactin in the blood.

  • Normally, Men and non-pregnant women have only small amounts of prolactin in their blood.
  • A high level of prolactin is normal during pregnancy and after childbirth while the mother is nursing.
  • Levels of prolactin that are below normal are not usually treated. But it may be indicative of a general decrease in pituitary hormones.

However, apart from this, a high level may also be seen with:

  • Tumors that produce and release prolactin
  • The eating disorder anorexia nervosa
  • Diseases of the hypothalamus
  • Hypothyroidism
  • Kidney disease
  • Liver disease
  • Polycystic ovary syndrome
  • Other pituitary diseases and tumors


Things Must Keep in Mind

  • Prolactin levels need to be evaluated based on the time of day that they are collected.
  • The levels vary over a 24-hour period, rising during sleep and peaking in the morning. Ideally, a person’s blood sample should be drawn 3 to 4 hours after waking.

Keywords: prolactin; PRL; pituitary gland; lactation

* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.