Prolactin

Prolactin is a polypeptide hormone secreted by the lactotrope cells of the anterior pituitary gland. Its primary physiological role is to stimulate mammary gland development and milk production (lactation), but it also plays a major role in regulating reproductive function, ovulation, immune response, and metabolism.

The release of prolactin is tightly regulated by dopamine, a neurotransmitter that acts as a natural inhibitor. When dopamine activity is suppressed — by stress, certain medications, or pituitary disorders — prolactin levels rise. Other hormones such as thyrotropin-releasing hormone (TRH) and oestrogen can also increase prolactin secretion.

Because prolactin interacts with reproductive hormones like oestrogen, progesterone, LH, and FSH, any imbalance can ripple through multiple systems — affecting fertility, menstrual regularity, libido, bone health, and mood regulation.

Prolactin is essential for female reproductive health and for maintaining a healthy hormonal rhythm across the lifespan.

• During pregnancy, prolactin prepares the breasts for milk production and supports mammary gland development.

• During lactation, it promotes milk synthesis and suppresses ovulation to prevent conception while breastfeeding.

• In non-pregnant women, prolactin contributes to hormonal balance, menstrual regularity, and ovarian function through its influence on gonadotropin-releasing hormone (GnRH) and downstream sex hormones.
  

When prolactin levels become abnormal, the effects can be wide-ranging:

• Elevated prolactin (hyperprolactinemia) can inhibit GnRH secretion, leading to decreased LH and FSH, low oestrogen levels, and anovulation. Clinically, this manifests as amenorrhea (absent periods), oligomenorrhea (infrequent periods), galactorrhea (unexpected milk production), infertility, low libido, and vaginal dryness.

• Low prolactin (hypoprolactinemia) is rare but may indicate pituitary or hypothalamic dysfunction, and can result in lactation failure postpartum and impaired ovarian signalling.

• Monitoring prolactin helps clinicians evaluate pituitary integrity, reproductive hormone balance, and the potential impact of stress, medications, or thyroid dysfunction on hormonal regulation.

Prolactin secretion follows a circadian rhythm, typically peaking during sleep and early morning hours. It is also influenced by physiological, psychological, and environmental factors:

Physiological Factors:
Prolactin naturally increases during pregnancy, lactation, ovulation, and sleep. It also rises transiently with sexual activity and nipple stimulation.

Stress Response:
Both physical and emotional stressors can elevate prolactin through suppression of dopamine and activation of the hypothalamic-pituitary-adrenal (HPA) axis. Chronic stress may contribute to sustained elevation, leading to menstrual disruption.

Medications:
Drugs that inhibit dopamine, such as antipsychotics (e.g., risperidone), antidepressants (SSRIs, tricyclics), oestrogens, oral contraceptives, and certain antihypertensives (verapamil, methyldopa), can increase prolactin.

Endocrine and Metabolic Disorders:

• Hypothyroidism: Low thyroid hormone increases TRH, which stimulates prolactin secretion.

• Pituitary Adenomas (Prolactinomas): Benign tumours that autonomously secrete prolactin, leading to sustained elevation and reproductive dysfunction.

• Chronic Kidney Disease and Liver Disease: Impaired clearance of prolactin can result in elevated levels.

Lifestyle Factors:
Poor sleep, excessive caffeine or alcohol, and nutrient deficiencies — especially vitamin B6, zinc, and magnesium — can alter dopamine synthesis and therefore prolactin control.

If Your Prolactin Is High

High prolactin is often a sign of dopamine imbalance or pituitary overactivity. It can lower testosterone, reduce libido, and cause fatigue or mood issues.

Diet:

• Focus on a Mediterranean-style diet emphasising lean proteins, colourful vegetables, whole grains, olive oil, and nuts.

• Include zinc-rich foods (oysters, pumpkin seeds, lean beef) and magnesium sources (spinach, cacao, almonds).

• Limit alcohol, processed sugars, and refined carbohydrates to stabilise insulin and reduce oxidative stress.
  

Lifestyle:

• Practice stress management techniques — deep breathing, yoga, or mindfulness can lower cortisol and support dopamine balance.

• Prioritise sleep: aim for 7–9 hours/night to normalise circadian prolactin rhythms.

• Engage in regular moderate exercise but avoid chronic overtraining.
  

Supplements (with clinician guidance):

• Vitamin B6 (20–50 mg/day) may help lower prolactin via dopamine pathways.

• Zinc (15–30 mg/day) and magnesium (200–400 mg/day) support hormonal regulation.
  

Additional Considerations

• Evaluate for thyroid dysfunction or pituitary abnormalities if prolactin remains elevated.

• Discuss medication review with your doctor — some drugs can raise prolactin unnecessarily.

If Your Prolactin Is Low

Low prolactin is uncommon but can reflect pituitary insufficiency, dopamine excess, or adrenal dysfunction.

Diet:

• Support hormone synthesis with whole-food fats (avocados, eggs, olive oil, wild fish).

• Ensure adequate protein and micronutrient intake (particularly zinc, magnesium, and B vitamins).
  

Lifestyle:

• Reduce excessive caffeine and stimulant use, which may over-activate dopamine and suppress prolactin.

• Get consistent sleep and maintain stable blood sugar to prevent hormone fluctuations.

• Incorporate relaxation and grounding activities, such as walking outdoors or breath-work.
  

Supplements (under medical guidance):

• DHEA (25–50 mg/day) may help restore hormonal balance if adrenal function is low.

• Vitamin C (500–1000 mg/day) supports adrenal health.

1. Current Evaluation of Amenorrhea: A Committee Opinion. Fertility and Sterility. 2024;122(1):52–61. doi:10.1016/j.fertnstert.2024.02.001.

2. Melmed S, Casanueva FF, Hoffman AR, et al. Diagnosis and Treatment of Hyperprolactinemia: An Endocrine Society Clinical Practice Guideline.The Journal of Clinical Endocrinology and Metabolism. 2011;96(2):273–288. doi:10.1210/jc.2010-1692.