Prolactin
| Clinical | Optimal | |
|---|---|---|
| Male | 86 - 324 mU/L | 86–324 mU/L |
| Female | 102 - 496 mU/L | 102–496 mU/L |
What is Prolactin?
Prolactin is a hormone produced by the anterior pituitary gland, a small structure at the base of the brain. While best known for its role in stimulating breast milk production after childbirth, prolactin has over 300 identified functions in the body, influencing reproduction, metabolism, immune regulation, and behaviour.
In both men and women, prolactin plays a role in reproductive health, immune system modulation, and the regulation of certain metabolic processes. Levels naturally fluctuate throughout the day, peaking during sleep and in response to stress, exercise, and meals.
Prolactin levels are tightly regulated by dopamine, which acts as the primary inhibitor of prolactin release. Any disruption to this dopamine-prolactin axis can lead to abnormal levels, which may have wide-ranging effects on health and wellbeing.
Why Prolactin Matters for Your Health
Prolactin is a valuable biomarker because abnormal levels can signal underlying issues with the pituitary gland, hypothalamus, or broader hormonal system. Elevated prolactin (hyperprolactinaemia) is one of the more common pituitary disorders and can cause disruptions to fertility, menstrual cycles, and sexual function in both sexes.
In the context of longevity and preventive health, prolactin offers insight into stress resilience, sleep quality, and dopaminergic function. Chronically elevated prolactin may indicate excessive stress, poor sleep, or an underlying pituitary issue that could benefit from early intervention.
For men, raised prolactin can suppress testosterone production, leading to reduced energy, libido, and muscle mass. For women, it can interfere with ovulation and oestrogen levels. Monitoring prolactin helps build a more complete picture of hormonal health.
Prolactin& Your Wearable Data
Prolactin is a pituitary hormone best known for its role in lactation but also involved in immune regulation, metabolism, and reproductive function in both sexes. Elevated prolactin can suppress gonadotropins (LH and FSH), leading to low testosterone in men and menstrual irregularity in women — symptoms detectable through wearable-tracked performance and cycle data.
Exercise and stress both acutely elevate prolactin. Your wearable's data showing intense exercise or high stress levels within hours of a blood draw may explain mildly elevated prolactin readings. The most accurate prolactin result requires testing in a rested, non-stressed state, ideally on a rest day visible in your wearable's activity log.
Sleep strongly influences prolactin, which peaks during deep sleep. Wearable sleep data showing poor sleep quality, reduced deep sleep, or fragmented sleep patterns may correlate with disrupted prolactin regulation. For individuals with hyperprolactinaemia, monitoring sleep improvements on their wearable alongside treatment helps assess response to medication.
What High Prolactin May Suggest
Elevated prolactin levels may suggest a range of conditions, from benign causes such as stress, poor sleep, or recent intense exercise, to more significant issues such as a prolactinoma (a non-cancerous pituitary tumour). Certain medications, including some antidepressants and antipsychotics, can also raise prolactin.
In women, high prolactin may be associated with irregular or absent periods, difficulty conceiving, and breast tenderness. In men, it may contribute to reduced libido, erectile difficulties, and in some cases breast tissue enlargement.
Mild elevations are common and often transient. However, persistently raised levels above 1000 mU/L typically warrant further investigation with imaging studies to assess the pituitary gland.
What Low Prolactin May Suggest
Low prolactin levels are relatively uncommon and generally not a cause for concern. However, very low levels may suggest hypopituitarism — a condition where the pituitary gland does not produce sufficient hormones. This can affect multiple hormonal pathways.
In women who have recently given birth, low prolactin may result in difficulty with breastfeeding. In the broader population, low prolactin has been associated in some research with reduced immune function and metabolic changes, though this area remains under investigation.
If results suggest very low prolactin alongside other low pituitary hormones, your GP may recommend further assessment of pituitary function.
How to Optimise Your Prolactin
Food
To help regulate prolactin naturally, focus on foods that support healthy dopamine production. Tyrosine-rich foods such as almonds, avocados, bananas, and chicken provide the building blocks for dopamine synthesis. Include vitamin B6-rich foods like chickpeas, potatoes, and sunflower seeds, as B6 is a cofactor in dopamine production. Zinc-rich foods including pumpkin seeds and shellfish support the dopamine-prolactin axis. Reduce excessive intake of refined carbohydrates, which may contribute to hormonal imbalance.
Lifestyle
Prioritise consistent, high-quality sleep, as prolactin levels are sensitive to sleep disruption. Manage stress through regular mindfulness practices, as chronic stress can elevate prolactin. Engage in moderate exercise rather than extreme endurance training, which can temporarily spike prolactin. Limit alcohol intake, particularly beer, which contains compounds that may raise prolactin. Reduce exposure to endocrine-disrupting chemicals in plastics and personal care products.
Supplements
Vitex agnus-castus (chasteberry) has evidence supporting its ability to help regulate prolactin levels, particularly in women. Vitamin B6 (pyridoxine) supports dopamine synthesis, which naturally inhibits prolactin release. Zinc supplementation may support the dopamine pathway and help maintain healthy prolactin levels.
When to Speak to Your GP
See your GP if prolactin levels are significantly elevated, particularly above 1000 mU/L, or if you experience symptoms such as unexplained breast discharge, visual disturbances, persistent headaches, irregular periods, or fertility difficulties. Men should seek advice if experiencing reduced libido or erectile changes alongside raised prolactin. Repeat testing may be recommended to confirm results, as stress during blood collection can temporarily raise levels.
References
- NHS. Prolactinoma — Overview. Updated 2024. nhs.uk
- NICE. Prolactinoma — Clinical Knowledge Summaries. cks.nice.org.uk
- Endocrine Society. Melmed S, et al. Diagnosis and treatment of hyperprolactinemia. J Clin Endocrinol Metab. 2011;96(2):273-288. pubmed.ncbi.nlm.nih.gov
- BMJ. Majumdar A, Mangal NS. Hyperprolactinemia. J Hum Reprod Sci. 2013;6(3):168-175. pubmed.ncbi.nlm.nih.gov
Medical Disclaimer— This content is for general educational and informational purposes only. It does not constitute medical advice, diagnosis, or treatment. Omniwo Ltd is a wellness information service and is not a medical device, clinical laboratory, or regulated healthcare provider under MHRA guidelines. The “optimal ranges” presented on this page are based on published clinical guidelines (WHO, NICE, NHS) and peer-reviewed research; they represent functional wellness targets and may differ from standard laboratory reference ranges. Individual results should always be interpreted by a qualified healthcare professional (such as your GP) who understands your full medical history. Do not start, stop, or change any medication or supplement based solely on this information. If you are experiencing symptoms, seek medical attention promptly.