Prolactin (Serum or Plasma) by Immunoassay

Why Is This Test Done?

Your doctor may order a prolactin test to check for conditions like hyperprolactinemia (high prolactin levels), which can affect fertility, menstrual cycles, or cause symptoms like breast tenderness or missed periods. It may also be used to evaluate pituitary gland function, thyroid disorders, or other hormonal imbalances. Rarely, it helps assess symptoms like headaches, vision changes, or unexplained weight gain.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to avoid certain medications (like certain antidepressants or antipsychotics) that can affect prolactin levels. If you’re taking them, your doctor will discuss how to proceed. For some tests, fasting may be required, but this is not typical for prolactin measurements.

What Happens During the Test?

A healthcare provider will draw blood from a vein in your arm. You may feel a small pinch, but it’s usually over quickly. The blood sample is then sent to a lab for analysis using an immunoassay method to measure prolactin concentration.

What Are Possible Results?

Results are typically reported as a numerical value representing the mass concentration of prolactin in your blood. Your doctor will compare this value to your individual reference range and discuss any findings with you.