Prolactin & Hyperprolactinemia
Prolactin's Suppression of the Gonadal Axis
Evidence grade 5 of 5, Settled. Read how the Atlas grades evidence.
The written rationale for this grade is still being prepared.
- FDA
- Endogenous hormone (a measured lab value)
Reference only. Not medical advice.
What can go wrong
The risk is twofold: missing a structural pituitary lesion, and mistreating elevated prolactin without finding the cause. Large prolactinomas can threaten vision via optic chiasm compression. Markedly elevated prolactin warrants pituitary imaging and endocrinology referral rather than simply prescribing testosterone, which would not correct the underlying problem.
This is something to take to a clinician. The Atlas can tell you what is known about prolactin & hyperprolactinemia in general. It cannot tell you what is happening in your body, and the difference matters most for exactly the symptoms that bring people to this page.
Prolactin is an anterior pituitary hormone best known for lactation, but in men persistently elevated prolactin (hyperprolactinemia) suppresses GnRH and therefore LH, FSH, and testosterone. It is an important, often-missed, and frequently reversible cause of low testosterone, low libido, and erectile dysfunction. Common drivers include prolactin-secreting pituitary tumors (prolactinomas), certain medications (notably some antipsychotics), and hypothyroidism.
A hidden, treatable cause of low testosterone and low libido.
What people take it for
What it is taken for. Approval, where it exists, covers only some of these.
How it works
Elevated prolactin inhibits the hypothalamic GnRH pulse generator, lowering LH and FSH and downstream testosterone. Prolactin is normally restrained by dopamine; this is why dopamine-agonist drugs lower prolactin and why dopamine-blocking medications can raise it. Macroprolactinemia (an inert large form) can produce falsely high readings and should be excluded.
What it does to fertility
By suppressing LH and FSH, hyperprolactinemia impairs spermatogenesis and can cause infertility; correcting prolactin often restores both testosterone and fertility, which is a key reason to identify it before starting exogenous testosterone.
What has to be monitored
The bloodwork this needs, and the reason it belongs with a clinician rather than a website.
- Serum prolactin (with macroprolactin exclusion if elevated)
- LH, FSH, testosterone
- Thyroid function (TSH)
- Pituitary MRI if prolactin substantially elevated
What people get wrong
Nothing recorded here yet. There is almost certainly something people get wrong about this one, and the blank space means we have not written it down, not that the record is clean.
Who profits, and who pushes back
Nobody is named here yet, because we have not done that work on this entry. Read that as unfinished. Somebody almost certainly sells this, and somebody almost certainly disputes it. Assume both until we have checked.
Set against the alternatives
Unlike most causes of low testosterone, hyperprolactinemia is frequently curable: treating the prolactinoma or removing the offending drug can restore the entire axis without lifelong testosterone replacement.
At a glance
- Effect of excess
- Suppresses GnRH, LH, FSH, testosterone
- Common cause
- Prolactinoma, drugs, hypothyroidism
- Workup trigger
- Low T with low/normal LH plus low libido
What this entry does not yet cover
What follows is unfinished work on our side, not a finding about Prolactin & Hyperprolactinemia. A short entry is not a safe entry.
- Timeline. We have not built the dated record of research and regulatory events.
- Cost and market. We have not documented what it sells for or who sells it.
- Supply chain. We have not mapped where it is made.
- Who uses it. We have not documented the user groups.
- What could change. No forward-looking summary yet.
- Children and teenagers. We have not checked what is known about younger people.
- Where we land. We have not taken a position on this yet.
Sources
The studies below are named and described, but not linked. You cannot open them from here and check our reading against them, which means this page is our summary of the literature rather than a document you can verify. Weigh it accordingly until the links exist.
The studies that matter
Endocrine Society guideline on hyperprolactinemia2011
Recommends measuring prolactin in men with hypogonadism, low libido, or erectile dysfunction and dopamine-agonist therapy as first-line for prolactinoma