Prolactin
A pituitary hormone best known for milk production. Outside that context, levels are checked when investigating hormone or fertility issues.
Typical reference range
| Range | Unit |
|---|---|
| 86–324 (male) | mU/l |
| 102–496 (female) | mU/l |
What Prolactin measures
Prolactin is a hormone made by the pituitary gland at the base of the brain. It is best known for enabling breast-milk production after childbirth, but it also plays a role in reproductive function across all sexes, influencing hormones tied to fertility and menstrual cycles. Prolactin does not stay perfectly steady through the day. Levels rise naturally during pregnancy and breastfeeding, and they can climb briefly with stress, poor sleep, exercise, and nipple stimulation. Because of this, timing and preparation matter: a calm, well-rested sample gives a more reliable picture than one drawn during a stressful or rushed moment. Your clinician reads prolactin alongside your symptoms and other hormone results rather than as a number on its own.
What a high Prolactin can mean
A higher-than-usual prolactin level is called hyperprolactinemia, and it has many possible explanations. Some are entirely normal, such as pregnancy or breastfeeding. Others reflect the sampling conditions themselves, like stress or recent nipple stimulation before the draw. Medical causes can include an underactive thyroid or a range of common medications (including some antipsychotics and anti-nausea drugs). Less commonly, it points to a benign, slow-growing pituitary tumor known as a prolactinoma.
- Irregular or absent menstrual periods
- Reduced libido or fertility difficulties
- Unexpected milk discharge from the breasts
Because so many everyday factors can nudge the value upward, a high result is often rechecked under proper conditions before any conclusions are drawn. Your clinician will weigh your medications, symptoms, and history when interpreting it.
What a low Prolactin can mean
A lower-than-usual prolactin level is usually not clinically significant and rarely calls for any action on its own. For most people it carries little meaning and does not signal a problem. Occasionally a persistently low value can relate to broader pituitary underactivity, where the gland produces less of several hormones, so a clinician may look at the fuller hormonal picture rather than prolactin alone.
What matters most here is context: how the sample was taken, your symptoms, your medications, and your other results all shape what a low reading means for you. On its own, a low prolactin is not a diagnosis. If your result is flagged as low, the sensible next step is to discuss it with your clinician, who can decide whether it fits your overall health or warrants any further look.
Track your Prolactin over time in Quanome — it reads your lab reports (PDF or photo) on your device, charts each marker against its range, and an AI coach explains what your trends mean alongside your Apple Health and DNA.