The word simply means underactive gonads. In men, hypogonadism is split by where the problem starts. Primary hypogonadism begins in the testes themselves, for example after injury, infection, chemotherapy or because of a genetic condition. Secondary hypogonadism begins in the pituitary or hypothalamus, which stop sending enough LH and FSH to the testes.
The type many men hear about in middle age is late-onset hypogonadism, sometimes loosely called andropause. That label is controversial, because testosterone falls gradually with age in most men and a low number is not the same as a disease. Researchers have worked to pin down when a low level genuinely causes symptoms.2
Remember that the testes have two jobs, making testosterone and making sperm, and hypogonadism can affect either or both. A man with normal testosterone can still have a sperm problem; that side of things is covered under male infertility.
What are the symptoms of hypogonadism?
The symptoms most tightly linked to low testosterone are sexual: fewer morning erections, low sexual desire and erectile dysfunction. In a study of 3,369 European men, only these three had a consistent syndromic link with low levels.2
Fatigue, low mood and reduced physical vigour were also associated with lower testosterone, but less specifically, because plenty of other things cause them.2 The researchers proposed a practical definition: at least three sexual symptoms, total testosterone under 11 nmol/L and free testosterone under 220 pmol/L.2 Our explainer on morning wood covers why that particular symptom is such a useful signal.
- Fewer or weaker morning erections
- Low sexual desire (libido)
- Erectile dysfunction
- Less specific: tiredness, low mood, reduced vigour
How is hypogonadism diagnosed?
The Endocrine Society recommends diagnosing it only in men with consistent symptoms and unequivocally low testosterone, measured as fasting morning total testosterone and confirmed with a repeat test.1
If total testosterone is borderline or SHBG is likely to be abnormal, free testosterone should be measured or accurately calculated. Once deficiency is confirmed, the guideline recommends further tests to find the cause.1 That usually means LH and FSH, and often prolactin, because the cause shapes the treatment.
What is the difference between primary and secondary hypogonadism?
Primary means the testes are failing, so LH is high; secondary means the brain's signal is weak, so LH is low or normal. In men aged 40 to 79, the secondary pattern was far more common, at 11.8% compared with 2.0% for primary.3
The same study linked a body mass index of 30 or more strongly with the secondary pattern, and older age with the primary pattern.3 It also described a third, compensated state in 9.5% of men, where testosterone was normal but only because LH was working overtime.3 Secondary hypogonadism linked to excess weight may be partly reversible, which is one reason finding the cause matters.
How common is low testosterone with age?
Low readings become common as men age. In the Baltimore Longitudinal Study of Aging, about 20% of men over 60, 30% over 70 and 50% over 80 had total testosterone in the hypogonadal range.4
Those figures describe blood levels, not symptoms, and many of those men would not meet a stricter definition that also requires sexual symptoms.2 That gap is why guidelines insist on both. There is more on the practical picture in how testosterone changes after 40. If you recognise the sexual symptoms above, it is worth a conversation with your GP.
Common questions
Can hypogonadism be reversed?
Sometimes. Secondary hypogonadism linked to obesity, medicines or illness may improve if the cause is dealt with, and obesity is strongly associated with that pattern.3 Primary hypogonadism caused by testicular damage is usually permanent and may need long-term treatment.
Is hypogonadism the same as andropause?
Not quite. Andropause is an informal term implying all men go through a hormonal change like menopause, which they do not. Late-onset hypogonadism is a narrower diagnosis needing both symptoms and consistently low testosterone.2
Does hypogonadism affect fertility?
It can, especially primary hypogonadism, which often affects sperm production as well as testosterone. Testosterone treatment itself suppresses sperm production, so guidelines advise against it in men planning to conceive soon.1
Read more on this
How testosterone changes after 40 (and what actually helps)
Does testosterone affect sex drive? Separating myth from mechanism
Morning wood explained: what it does (and doesn’t) tell you about your health
Sources
- Bhasin S, et al. Testosterone therapy in men with hypogonadism: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2018;103(5):1715-1744. PubMed
- Wu FC, et al. Identification of late-onset hypogonadism in middle-aged and elderly men. N Engl J Med. 2010;363(2):123-135. PubMed
- Tajar A, et al. Characteristics of secondary, primary, and compensated hypogonadism in aging men: evidence from the European Male Ageing Study. J Clin Endocrinol Metab. 2010;95(4):1810-1818. PubMed
- Harman SM, et al. Longitudinal effects of aging on serum total and free testosterone levels in healthy men. Baltimore Longitudinal Study of Aging. J Clin Endocrinol Metab. 2001;86(2):724-731. PubMed
Not medical advice. Written by Eric Stephens from the research cited above; not reviewed by a doctor. If something worries you, see a GP.