Normal Prolactin Levels in Women: Age Table and What the Numbers Mean

A prolactin test result is a single number, and it almost always raises a question: is it within the normal range. Below are reference ranges, units of measurement, and circumstances that shift the value without disease.

Prolactin: what this hormone is and what it does

Prolactin (PRL on lab forms) is a peptide hormone of the anterior pituitary gland, a small gland at the base of the brain. Its main target is the mammary glands: the hormone stimulates their growth and development, supports lactation, and increases the secretion of colostrum and its conversion into mature milk. Receptors are also found in other organs, but whether the hormone acts there is not yet known.

Production is controlled by the hypothalamus through inhibition: dopamine suppresses prolactin release, and when dopamine decreases, the level rises; estrogens, by contrast, stimulate synthesis and secretion. The test is ordered when a pituitary tumor is suspected and when investigating the causes of milk discharge outside of breastfeeding, reduced libido, infertility, and menstrual irregularities.

Normal prolactin levels in women: table by age and condition

Reference limits are tied not to age but to physiological state, which affects the number most strongly. MedlinePlus (USA) reference ranges:

Separate limits for girls, women of reproductive age, and menopause are not given here. Intervals differ slightly between laboratories, and some laboratories use other units and samples, so check against the range on your own lab form.

Key points to remember: the upper limit in a non-pregnant woman is 25 mcg/L, and during pregnancy it is 500 mcg/L.

Units of measurement

The result is usually expressed in mcg/L; 25 nanograms per milliliter is the same as 25 mcg/L. If your form uses other units, rely on the laboratory's reference interval and check with your doctor.

What the result depends on: stress, pregnancy, medications

Blood is drawn on an empty stomach; no special preparation is needed. Prolactin is temporarily raised by stress, emotional or physical, sometimes; protein food, intense stimulation of the mammary glands, a recent breast examination, and recent exercise. It is higher in anxiety, depression, severe pain, psychoses, during pregnancy, and especially during breastfeeding: during pregnancy lactation is inhibited by progesterone, and progesterone falls after the placenta is delivered.

An elevated result is repeated early in the morning after an eight-hour fast. The level is altered by medications: antidepressants, estrogens, metoclopramide, opioids, risperidone, verapamil; cannabis products also raise it. A separate matter is macroprolactin, a large form of the molecule that is cleared more slowly.

What elevated results mean

High prolactin occurs in various conditions, and it is not always about a tumor. The doctor works through the causes in order:

• prolactinoma, a hormone-producing pituitary tumor, and other tumors or diseases in the pituitary region;
• hypothyroidism, that is, a deficiency of thyroid hormones, and kidney disease;
• hypothalamic diseases, trauma or irritation of the chest wall, nipple piercing;
• medications and cannabis products, macroprolactin with slowed clearance of the molecules.

Interpreting an elevated result is not straightforward: most often the doctor refers the patient to an endocrinologist, who deals with hormonal problems. There is no reliable information here about low prolactin, so leave interpretation to the doctor; in pituitary diseases there is often too much or too little of one of its hormones, and the most common cause of such disorders is a pituitary tumor.

Key point to remember: a high number is a reason to look for the cause, not a ready-made diagnosis.

When to see a doctor

The reason is not only the number but also symptoms: milk discharge outside of breastfeeding, irregular or absent periods, inability to conceive, reduced libido. People also see a doctor with a repeatedly elevated result, and the doctor decides which examinations are needed.

Elevated or low prolactin by itself is not a reason to call an ambulance. 103/112 — if the condition is life-threatening: signs of stroke, heart attack, severe trauma.

This material is for reference and does not replace a doctor's consultation: decisions about further steps are made based on your test results and examination.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer