Thyroid disorders

Thyroid hormone regulates the metabolic rate of essentially every tissue, so it is unsurprising that both directions of imbalance affect sexual function. What is surprising is how rarely thyroid function is checked in a man presenting with erectile dysfunction.

How each presents
Hypothyroidism (underactive)Hyperthyroidism (overactive)
Sexual patternMore often erectile dysfunction, low libido, delayed ejaculationMore often premature ejaculation; ED also reported
General symptomsFatigue, weight gain, cold intolerance, constipation, dry skin, low moodWeight loss, heat intolerance, palpitations, anxiety, tremor, loose stools
Related hormonesCan raise prolactin, adding a second mechanismRaises SHBG, which lowers free testosterone
ReversibilitySexual symptoms commonly improve once treated and stableCommonly improve once treated and stable

High prolactin (hyperprolactinaemia)

Prolactin is best known for lactation, but in men its main relevance is that raised levels suppress gonadotropin-releasing hormone. Less GnRH means less LH, less LH means less testosterone — and the result is low libido and erectile dysfunction, often with fatigue and low mood.

The diagnostic clue worth knowing

If testosterone is low and LH is high, the testicles are the problem. If testosterone is low and LH is low or inappropriately normal, the problem is upstream — in the pituitary or hypothalamus — and prolactin should be measured. This single distinction is what separates a proper hormonal workup from a superficial one.

What raises prolactin

  • Prolactinoma — a benign pituitary tumour, and the most important cause to exclude. Large ones can press on the optic chiasm and cause visual field loss.
  • Medications — antipsychotics (especially risperidone and haloperidol), metoclopramide, domperidone, some antidepressants, verapamil, opioids.
  • Hypothyroidism — which is why the two tests belong together.
  • Chronic kidney disease and cirrhosis.
  • Stress, recent nipple stimulation, or a recent seizure — all can raise a single reading transiently, which is why abnormal results are repeated.

What treatment looks like

  1. Confirm the abnormality — thyroid and prolactin results are repeated before acting, since transient elevations are common.
  2. Identify the cause — medication review first, then imaging where a pituitary cause is suspected.
  3. Treat the underlying condition — thyroid replacement or antithyroid treatment; dopamine agonists such as cabergoline for a prolactinoma, which often shrink the tumour as well as normalising the hormone.
  4. Re-check testosterone afterwards. Correcting prolactin frequently restores testosterone without any need for replacement — which matters a great deal if you want children, since testosterone therapy suppresses fertility.
  5. Give it time. Sexual symptoms typically improve over weeks to months once hormone levels stabilise, not overnight.
FAQ

Frequently asked questions

Should thyroid be checked for erectile dysfunction?
It is inexpensive, and both underactive and overactive thyroid are associated with sexual dysfunction and are reversible. It is reasonable to request it, especially with any general thyroid symptoms.
What does high prolactin mean?
It suppresses testosterone production, causing low libido and erectile dysfunction. Causes include medications, an underactive thyroid, kidney disease and a benign pituitary tumour — which needs excluding.
Will treating these fix my ED?
Frequently, where they are the main driver, though improvement takes weeks to months. They are among the more genuinely reversible causes.
Can antidepressants raise prolactin?
Some can, and antipsychotics commonly do. Never stop a psychiatric medication on your own — raise it with your prescriber, since alternatives often exist.
Sources

What this is based on

We link to primary sources — clinical guidelines, regulator publications and peer-reviewed research — wherever possible. Links open on third-party sites we do not control.

  1. [01]Endocrine Society. Testosterone Therapy in Men With Hypogonadism — clinical practice guideline (2018).
  2. [02]American Urological Association. Testosterone Deficiency: AUA Guideline (2018).
  3. [03]MedlinePlus (National Library of Medicine). Drugs, Herbs and Supplements.
  4. [04]National Institute of Diabetes and Digestive and Kidney Diseases. Definition & Facts for Erectile Dysfunction.