Prolactin tests measure the concentration of prolactin — a hormone produced mainly by the anterior pituitary gland — in the blood. Clinically they are used to investigate symptoms such as unexplained milk production (galactorrhea), menstrual irregularities, infertility, low libido, and to monitor known pituitary lesions.

As cancer indicators, prolactin tests are not general markers for malignancy. Markedly elevated prolactin most commonly indicates a prolactin-secreting pituitary tumor (prolactinoma), which is usually a benign pituitary adenoma; mild-to-moderate rises are more often caused by medications, pregnancy, hypothyroidism, stress, or assay artifacts (e.g., macroprolactin). Rarely, non‑pituitary tumors may be associated with raised prolactin, but prolactin measurement is not used to screen for cancer — abnormal results prompt endocrine evaluation and often pituitary imaging rather than cancer screening.

Prolactin is measured from a standard venous blood sample drawn by a phlebotomist—typically a small tube of blood taken from a vein in your arm at a clinic or laboratory.

Because prolactin levels rise with stress, exercise, nipple stimulation and certain medicines, labs usually collect the sample in the morning after 15–30 minutes of rest and ask you to avoid vigorous activity beforehand; always follow any specific prep instructions from your provider and tell them about medications you’re taking.

A prolactin blood test measures the hormone prolactin and is not a general cancer screening test. Elevated prolactin most commonly reflects benign causes — for example pregnancy or breastfeeding, certain medications, hypothyroidism, chest wall stimulation, or kidney/liver problems — and can also be caused by a prolactin-secreting pituitary tumor (prolactinoma). The degree of elevation matters: modest rises are often due to non‑tumor causes, while very high values are more suggestive of a prolactin‑secreting pituitary adenoma, but prolactin alone cannot diagnose cancer or predict overall cancer risk.

If your prolactin is abnormal, clinicians usually repeat the test and check for common causes (pregnancy test, review medicines, thyroid and kidney function) before imaging. If a pituitary tumor is suspected, an MRI and endocrine referral are typical next steps. Normal or low prolactin levels do not reliably rule in or out cancer; use of prolactin for assessing personal cancer risk is limited and follow-up should be guided by your clinician.

Prolactin testing is useful for detecting prolactin-secreting pituitary tumors (prolactinomas): very high concentrations (commonly reported thresholds around >200 ng/mL) are strongly suggestive of a prolactinoma, but mild-to-moderate elevations are nonspecific and can result from medications, stress, pregnancy, hypothyroidism, renal failure, chest stimulation or the presence of macroprolactin. Repeat testing under standardized conditions and screening for macroprolactin improve accuracy.

Prolactin is not a reliable general cancer marker and is not used to screen for non‑pituitary cancers; diagnosis of a prolactinoma requires correlation with symptoms and pituitary MRI, and abnormal results should be evaluated by an endocrinologist for appropriate follow‑up and imaging.

Prolactin testing is not a routine cancer screen — markedly raised prolactin most commonly reflects a pituitary prolactinoma or non‑cancer causes (medications, pregnancy, hypothyroidism, stress). How often you should test depends on the reason for testing: if an initial result is abnormal it should be confirmed with a repeat fasting sample, and if a pituitary adenoma is suspected you will be managed and monitored by your clinician.

Typical monitoring schedules used in practice are: check a repeat baseline to confirm elevation; if you start treatment (dopamine agonist) recheck prolactin within 2–4 weeks to ensure response, then every 3 months until levels and symptoms are stable, and thereafter every 6–12 months. For untreated small (micro) prolactinomas many clinicians monitor levels and imaging every 6–12 months; for larger (macro) lesions testing and imaging is more frequent. Recheck any time symptoms change or when new medications are started. Follow the testing interval recommended by your treating physician for your specific situation.

No — prolactin test results are not diagnostic for cancer or other specific diseases on their own; they reveal patterns of hormonal imbalance or resilience in prolactin regulation, which can be influenced by many factors (stress, medications, physiological states, or pituitary changes) rather than serving as a standalone medical diagnosis.

Prolactin values must be interpreted in the context of symptoms, medical history, medications and other laboratory or biomarker data by a qualified clinician, who can decide whether further evaluation (imaging, repeat testing, or specialist referral) is warranted.

Prolactin testing is not a general cancer screen — elevated prolactin most often reflects benign causes such as pregnancy or breastfeeding, certain medications (e.g., some antipsychotics or antiemetics), hypothyroidism, chest wall stimulation, stress, or a benign pituitary adenoma (prolactinoma). Because the correct approach depends on the cause, an elevated result usually prompts repeat testing under standard conditions and clinical assessment rather than an assumption of cancer.

To improve abnormal prolactin levels you should follow your clinician’s plan: repeat the blood test (morning, fasting, avoid nipple or chest stimulation and strenuous exercise beforehand), review and if appropriate change medicines that raise prolactin with your prescriber, treat underlying conditions such as hypothyroidism, and—if a prolactinoma is suspected—see an endocrinologist for imaging and possible medical therapy (dopamine agonists such as cabergoline or bromocriptine under supervision). General measures that can help include stress reduction and avoiding recreational drugs or substances known to raise prolactin; always coordinate changes and treatment with your healthcare provider and obtain follow‑up testing and specialist referral when recommended.