Many symptoms linked to low testosterone are common and can have other explanations. The Endocrine Society guideline states that the symptoms and signs of testosterone deficiency are nonspecific and are modified by age and comorbid illness. That is why the guideline pairs symptoms with repeated lab tests before a diagnosis.
What hypogonadism is
MedlinePlus defines hypogonadism as the sex glands, the testes in men, producing little or no hormones. It can be primary, starting in the testes, or secondary (central), starting in the pituitary or hypothalamus. In men, MedlinePlus lists breast enlargement, muscle loss and low libido as symptoms, and says hypogonadism may cause impotence, infertility, osteoporosis and weakness.
Symptoms and low levels do not always go together
In the Boston Area Community Health Survey of 1,475 randomly selected men aged 30 to 79, about 24% had total testosterone below 300 ng/dL, but the crude prevalence of symptomatic androgen deficiency was 5.6%. Many men with low testosterone had no symptoms, including 47.6% of men aged 50 and older. Symptomatic deficiency rose from 3.1 to 7.0% in men under 70 to 18.4% among men in their 70s.
The European Male Aging Study surveyed a random sample of 3,369 men aged 40 to 79 at 8 European centers. Only 3 sexual symptoms (poor morning erection, low sexual desire and erectile dysfunction) had a syndromic association with low testosterone. The study proposed defining late-onset hypogonadism as at least 3 sexual symptoms plus total testosterone below 11 nmol/L (3.2 ng/mL) and free testosterone below 220 pmol/L (64 pg/mL).
Both were observational surveys. They show how often symptoms and low levels overlap in a population, not what causes any one man's symptoms.
Conditions and situations that affect testosterone
The Endocrine Society guideline states that testosterone levels are affected by age, obesity, diabetes and sleep disorders including obstructive sleep apnea, and it lists severe obesity among causes of secondary hypogonadism. It also notes levels may be affected by acute illness, nutritional deficiency and certain medications, such as opioids, that suppress testosterone. MedlinePlus lists further causes.
| Question | What the source says |
|---|---|
| What can cause primary hypogonadism? | Autoimmune disorders, genetic disorders such as Klinefelter syndrome, infection, iron excess, liver and kidney disease, radiation, surgery and trauma. |
| What can cause central hypogonadism? | Medicines such as glucocorticoids and opiates, stopping anabolic steroids, pituitary bleeding or tumors, rapid weight loss, nutritional deficiencies and trauma. |
| What else affects testosterone levels? | Age, obesity, diabetes, sleep disorders including obstructive sleep apnea, acute illness, nutritional deficiency and medications such as opioids. |
Why one test is not enough
The guideline text says about 30% of men with an initial testosterone value in the hypogonadal range have a normal value when it is measured again, and that testosterone peaks in the morning. It says clinicians should not test men for deficiency while they have, or are recovering from, an acute illness, or while they are using short-term medications such as opioids that suppress testosterone.
The Endocrine Society recommends diagnosing hypogonadism only with consistent symptoms and signs plus unequivocally low testosterone, confirmed by repeat fasting morning total testosterone measurements. Age also shapes how results are read. MedlinePlus notes that testosterone declines with age, that the normal range is lower in men aged 50 to 60 than in men aged 20 to 30, and that test interpretation in older or obese men can be difficult.
What this does not tell you
This guide does not tell you which cause explains your symptoms. A symptom list cannot confirm or rule out low testosterone, and these sources do not rank how often each other condition is the real explanation. The Endocrine Society guideline is advice to clinicians, not a law. A licensed provider decides what to test, when to test it and how to read the results.