Prolactin (baseline)

Prolactin is a hormone made by the pituitary gland that supports milk production, reproductive function, and sexual health. This test measures the amount of prolactin circulating in your blood at baseline, either as a single check or as the starting sample in a dynamic pituitary study.

Your blood is drawn from a vein. Some laboratories prefer a calm, morning collection because stress, recent exercise, or nipple stimulation can temporarily raise prolactin levels. The measurement helps your clinician understand how your pituitary and related systems are functioning.

Clinicians order prolactin testing for symptoms such as unexpected breast milk discharge, irregular or absent periods, infertility, low libido, or erectile dysfunction. It is also used when headaches or vision changes raise concern for a pituitary problem, and to monitor known prolactin producing tumors or the effects of treatment.

Results can help distinguish medication effects, thyroid disease, pregnancy, and kidney or liver conditions from pituitary causes. Tracking results over time guides decisions about medication that lowers prolactin, the need for imaging, and other care plans tailored to your situation.

A higher than expected result is common and may reflect stress during the blood draw, certain medications, or physiologic states like pregnancy and breastfeeding. If your level is elevated, your clinician may repeat the test under calmer conditions, review your medications, and check thyroid function. Sometimes a specialized check for macroprolactin is done, since this form can raise results without causing symptoms.

A low result is less common and usually has limited clinical impact, but in the right context it can point to pituitary or hypothalamic issues. If results remain abnormal without a clear explanation, your clinician may order additional tests or imaging of the pituitary and discuss the next steps with you.