Serum Prolactin Level (Immunoassay)

Why Is This Test Done?

Doctors may order a prolactin test to check for conditions like high prolactin levels (hyperprolactinemia), which can interfere with normal hormone function. It’s often used when symptoms like irregular periods, infertility, or breast milk production persist despite pregnancy or hormone therapy. It may also be done to evaluate pituitary gland disorders or rule out potential tumors.

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 could affect results. If you’re breastfeeding or pregnant, let your doctor know. Avoid strenuous exercise or smoking right before the test, as these can temporarily alter hormone levels.

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’s quick and usually not painful. 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 compared to a reference range, but exact values can vary by lab. High levels may suggest conditions like pituitary tumors, thyroid issues, or certain medications. Low levels might indicate rare hormonal deficiencies, though this is less common. Your doctor will interpret results in the context of your symptoms and medical history.