Prolactin, Serum (Mass Concentration)

Why Is This Test Done?

Your healthcare provider may order a serum prolactin test to check for conditions like hyperprolactinemia (high prolactin levels), which can cause issues such as infertility, irregular menstrual cycles, or problems with milk production in nursing mothers. It may also be used to evaluate symptoms like headaches, vision changes, or unexplained galactorrhea (milk leakage from nipples). Additionally, it can help monitor treatment for conditions like pituitary tumors or other hormonal disorders.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if instructed by your provider. Wear comfortable clothing and plan to stay for about 15 minutes while blood is drawn. If you’re taking certain medications (like dopamine agonists), your provider may advise timing your dose around the test.

What Happens During the Test?

A healthcare professional will insert a needle into a vein in your arm or hand to collect a blood sample. You may feel a slight pinch, but the procedure is quick. The blood will be sent to a lab for analysis using an immunoassay method to measure prolactin concentration.

What Are Possible Results?

Results are typically reported as a mass concentration (often in nanograms per deciliter, ng/dL). Your provider will interpret the results in relation to your symptoms and medical history. Abnormal results may trigger further testing or follow-up.