Prolactin is best known as the pituitary hormone of lactation, but it plays a meaningful role in male physiology too. When levels rise inappropriately, the consequences ripple through the entire reproductive axis: testosterone falls, libido drops, erections weaken, and fertility declines. High prolactin in men — hyperprolactinemia — is the second most common pituitary problem after non-functioning adenomas, and it is sometimes the first clue to a benign pituitary tumor that has been growing silently for years. Most cases are treatable and many resolve completely with the right diagnosis.
What Prolactin Does in Men
In healthy men, prolactin circulates at low levels (typically under 15 to 20 ng/mL) and contributes to immune function, behavior, and modulation of sexual response. The hypothalamus tonically inhibits prolactin release through dopamine. When dopamine signaling drops or when a tumor produces prolactin autonomously, levels rise.
Elevated prolactin suppresses the hypothalamic-pituitary-gonadal axis by inhibiting GnRH pulsatility. The downstream effect is reduced LH, reduced testosterone production, and resulting symptoms of hypogonadism. The reproductive consequences of hyperprolactinemia are essentially mediated through this hormonal cascade.
What Causes Hyperprolactinemia
Causes are conventionally divided into physiologic, pharmacologic, pathologic, and idiopathic.
Physiologic prolactin elevation occurs after sexual activity, exercise, stress, sleep, and meals; isolated mildly elevated values often normalize on repeat testing under standardized conditions. The Endocrine Society Hyperprolactinemia Guideline recommends repeating an isolated mildly elevated prolactin before pursuing further workup.
Pharmacologic causes are common and important to identify. Antipsychotics (especially risperidone and first-generation agents) are the leading offenders, sometimes producing prolactin levels above 100 ng/mL. Other contributors include metoclopramide, methyldopa, verapamil, SSRIs (modest elevations), opioids, and estrogens. Recreational substances including cannabis can also raise prolactin.
Pathologic causes include pituitary adenomas (prolactinomas — the most common functional pituitary tumor, accounting for about 40% of pituitary adenomas), other pituitary masses compressing the stalk and disrupting dopamine inhibition, hypothyroidism (TRH stimulates prolactin release), chronic kidney disease, cirrhosis, and chest wall lesions. Macroprolactin — a large biologically inactive complex that immunoassays sometimes misread — produces falsely elevated values without clinical significance and should be excluded with polyethylene glycol precipitation in unclear cases.
Symptoms
The reproductive symptoms reflect downstream hypogonadism: reduced libido, erectile dysfunction, infertility, decreased ejaculate volume, gynecomastia (occasional), and rarely galactorrhea (men can produce small amounts of breast milk under prolonged hyperprolactinemia). Long-standing hypogonadism leads to reduced energy, decreased muscle mass, and bone loss.
Symptoms specific to a pituitary tumor depend on its size. Small tumors (microadenomas under 10 mm) produce only the hormonal symptoms. Larger tumors (macroadenomas over 10 mm) can compress adjacent structures, producing headaches, visual field defects (classically bitemporal hemianopsia from compression of the optic chiasm), and less commonly cranial nerve palsies. Macroadenomas also can compress and damage normal pituitary tissue, producing combined hormonal deficiencies.
How High Prolactin Is Diagnosed
Workup starts with a fasting morning prolactin level drawn at least 2 hours after waking. Mild elevations are confirmed on repeat testing under standardized conditions. Markedly elevated values — typically over 100 ng/mL — strongly suggest a prolactinoma and warrant pituitary MRI. Levels in the hundreds of ng/mL or higher reflect macroadenomas in most cases.
Additional testing includes TSH (rule out hypothyroidism as a cause), creatinine (rule out renal failure), liver function, hCG, and a thorough medication review. The Mayo Clinic recommends pituitary MRI for any unexplained elevation that is not explained by medication or a clear secondary cause. Visual field testing is performed when a macroadenoma is found near the optic chiasm.
Anterior pituitary function should be evaluated when a macroadenoma is identified — testosterone, LH, FSH, free T4, ACTH-stimulated cortisol, and IGF-1 to assess for combined hormonal deficits.
Treatment Options
Treatment depends on cause. For medication-induced hyperprolactinemia in patients without symptomatic concerns, no treatment may be needed; otherwise, switching to a less prolactin-elevating alternative (for psychiatric medications, switching to aripiprazole or working with the prescribing psychiatrist) often normalizes levels. Treating hypothyroidism with levothyroxine corrects prolactin elevation in those cases.
For prolactinomas, dopamine agonists are the first-line treatment and remarkably effective. Cabergoline (typically 0.25 to 1.0 mg twice weekly) is generally preferred because of its better efficacy, longer half-life, and better tolerability than older bromocriptine. Dopamine agonists normalize prolactin in roughly 80 to 90% of microadenomas and a similar percentage of macroadenomas, often shrinking macroadenomas by 50% or more within months. Symptoms — libido, erectile function, fertility — frequently restore as testosterone normalizes.
Side effects of dopamine agonists include nausea, dizziness, orthostatic hypotension, and rarely impulse control disorders. High-dose cabergoline (more typical in Parkinson disease than in prolactinoma) has been associated with cardiac valvulopathy, but typical prolactinoma doses appear safe.
Surgery (transsphenoidal resection) is reserved for prolactinomas that do not respond to or are not tolerated by dopamine agonists, for tumors causing acute visual symptoms, or for pituitary apoplexy. Radiotherapy is rarely needed and is reserved for refractory cases. Surgical cure rates depend on tumor size and surgeon experience, with microadenoma success rates of 70 to 90% in experienced centers.
When to See a Doctor
Persistent reduced libido, erectile dysfunction, or unexplained gynecomastia in a man with low testosterone warrants prolactin testing as part of the workup. Headaches with visual disturbances, especially loss of peripheral vision, deserve urgent evaluation because pituitary macroadenoma is a possibility. Galactorrhea in a man, while uncommon, always warrants evaluation. Men with infertility should have prolactin checked as part of the reproductive workup.
For overlapping concerns, see the low testosterone guide, low libido in men, erectile dysfunction, and the broader medical conditions hub.
Frequently Asked Questions
What is a normal prolactin level for men?
Reference ranges differ slightly by lab, but most consider total prolactin under 15 to 20 ng/mL as normal in adult men. Mildly elevated values (20 to 50 ng/mL) require repeat testing under standardized conditions. Values over 100 ng/mL strongly suggest a prolactinoma and warrant pituitary imaging.
Can stress cause high prolactin?
Acute stress, recent sexual activity, exercise, and even venipuncture can transiently raise prolactin. This is why isolated mildly elevated values are typically repeated after a calm rest period before further workup. Chronic stress alone does not produce the persistent elevations seen with prolactinomas.
Will high prolactin make me infertile?
Hyperprolactinemia commonly impairs spermatogenesis through the suppression of GnRH and downstream LH/FSH/testosterone. Treatment usually restores fertility within months. Reproductive urology evaluation is appropriate for men whose hyperprolactinemia is identified during a fertility workup.
Are prolactinomas cancerous?
No. Prolactinomas are benign adenomas — they do not metastasize. Macroadenomas can cause significant local effects through size, but they remain histologically benign in essentially all cases. Treatment with dopamine agonists or surgery typically controls the tumor effectively.
The Bottom Line
High prolactin in men is a treatable condition with broad consequences for sexual function and fertility. Pharmacologic causes are common and reversible by switching medications. Pathologic causes — most commonly a benign pituitary tumor — respond remarkably well to dopamine agonists in the great majority of cases. The diagnostic workup is straightforward, and recognizing prolactin elevation often unlocks an explanation for symptoms that have been frustrating men and their clinicians for years. A primary care physician, urologist, or endocrinologist can coordinate evaluation and ongoing management.