Prolactin by Immunoassay (Serum/Plasma)

Why Is This Test Done?

Your doctor may order a prolactin test to check for conditions like hyperprolactinemia (high prolactin levels), which can cause issues like infertility, irregular menstrual cycles, or symptoms like breast tenderness. It may also be used to evaluate pituitary tumors or other hormonal disorders. Sometimes, it’s checked alongside other tests if you have symptoms such as headaches, vision problems, or unexplained weight changes.

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. Wear comfortable clothing for blood draws. If you’re taking medications that affect prolactin levels (like certain antidepressants or antipsychotics), let your doctor know beforehand.

What Happens During the Test?

A healthcare provider will draw blood from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause discomfort. The blood sample is then sent to a lab for analysis using an immunoassay method to measure prolactin concentration.

What the Results Mean

Results are reported as a mass concentration in units like nanograms per deciliter (ng/dL). While reference ranges vary by lab, high or low levels may signal underlying health concerns that need further evaluation, such as thyroid issues, pregnancy, or certain medications.