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Testosterone Blood Test: What Your Results Mean

Testosterone is the primary male sex hormone, though it is also present and important in women at much lower concentrations. In men, it is produced mainly in the testes; in women, by the ovaries and adrenal glands. Testosterone regulates sex drive, muscle mass, bone density, fat distribution, red blood cell production, and mood. Testing is done in the morning when levels are naturally highest.

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Normal Range

300 – 1000 ng/dL (men), 15 – 70 ng/dL (women)

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Unit

ng/dL

What Your Results Mean

Normal

A normal testosterone level indicates healthy gonadal function and appropriate hormonal balance. In men, this supports reproductive function, muscle maintenance, and energy. In women, it contributes to libido, bone density, and overall well-being.

High

In men, high testosterone may result from testosterone replacement therapy, anabolic steroid use, or — rarely — testicular or adrenal tumours. In women, elevated testosterone is most commonly caused by polycystic ovary syndrome (PCOS), congenital adrenal hyperplasia, or androgen-secreting tumours. Symptoms in women include acne, excess facial and body hair (hirsutism), and irregular periods.

Low

Low testosterone (hypogonadism) in men causes fatigue, reduced libido, erectile dysfunction, decreased muscle mass, increased body fat, mood changes, and reduced bone density. Causes include ageing (testosterone declines ~1% per year after age 30), obesity, chronic illness, sleep apnoea, or pituitary and testicular disorders.

Frequently Asked Questions

What are the symptoms of low testosterone in men? expand_more
Symptoms include reduced sex drive, fatigue and low energy, loss of muscle mass, increased body fat (especially around the abdomen), erectile dysfunction, mood changes (irritability, depression), reduced bone density, and difficulty concentrating. These symptoms are non-specific and require a blood test to confirm low testosterone.
Why should testosterone be tested in the morning? expand_more
Testosterone follows a diurnal rhythm — levels are highest in the morning (typically 7–10 AM) and fall throughout the day. Testing in the morning ensures the most accurate and reproducible result. An afternoon reading can be 15–30% lower than a morning reading in the same person.
What causes high testosterone in women? expand_more
Polycystic ovary syndrome (PCOS) is the most common cause of elevated testosterone in women. Other causes include congenital adrenal hyperplasia, androgen-secreting tumours (rare), and anabolic steroid use.
Is testosterone replacement therapy safe? expand_more
Testosterone replacement therapy (TRT) can be effective for men with confirmed hypogonadism. Potential risks include polycythaemia (increased red blood cells), infertility (suppressed sperm production), sleep apnoea worsening, and — at high doses — cardiovascular risk. It should be monitored regularly by a physician.
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