Testosterone

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What is testosterone?
Where is testosterone produced?
Function of testosterone
Testosterone in women
Testosterone in men
Normal testosterone levels
Causes of high testosterone
Causes of low testosterone
When and how to test testosterone
Testosterone in traditional Chinese medicine
Acupuncture and testosterone
Chinese herbal medicine and testosterone
Diet, supplements and lifestyle
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1. What is testosterone?

Testosterone is the primary male androgen hormone. Although often thought of as a "male hormone", testosterone is also produced and is essential in women, where it supports follicle growth, libido, mood, energy and bone density. Testosterone levels in men are about 10–20 times higher than in women.

Testosterone exists in two forms in the blood: bound testosterone (attached to SHBG, biologically inactive) and free testosterone (unbound, biologically active). Only 1–3% of total testosterone is free at any time.

Reference ranges vary from country to country and between laboratories. Always interpret your own result against the reference range provided by the laboratory that performed your test.

2. Where is testosterone produced?

In women, testosterone is produced in roughly equal proportions by:

Adrenal glands (25%).
Ovaries (25%).
Adipose (fat) tissue, where DHEA and androstenedione are converted to testosterone (50%).

In men, the great majority of testosterone is produced by the Leydig cells of the testes, with a small contribution from the adrenal glands.

3. Function of testosterone

Testosterone has many functions in both sexes:

Drives sexual desire (libido) in both men and women.
Supports muscle mass, strength and bone density.
Maintains energy and mood.
Supports red blood cell production.
In women, supports the growth of small ovarian follicles and is converted to oestradiol within the granulosa cells.
In men, drives sperm production, secondary sexual characteristics, deepening of the voice, body hair and muscle development.

4. Testosterone in women

In women, testosterone is essential for follicle growth — small early-stage follicles depend on local androgens, which are converted to oestrogens as they mature. Modest levels of testosterone are therefore beneficial for fertility. However, excess testosterone — as in PCOS — disrupts the normal cyclical release of FSH and LH, causes anovulation, hirsutism and acne, and contributes to insulin resistance.

5. Testosterone in men

In men, testosterone is essential for sperm production via its action on the seminiferous tubules. Low testosterone (hypogonadism) reduces sperm count, libido and erectile function. The level of dihydrotestosterone (DHT, derived from testosterone) within the testis is several-fold higher than circulating testosterone and is the dominant driver of spermatogenesis.

6. Normal testosterone levels

Typical reference ranges:

Total testosterone in women: 0.5–3.6 nmol/L (14–103 ng/dL).
Total testosterone in men: 8–30 nmol/L (230–860 ng/dL), although ranges vary widely.
Free testosterone in women: approximately 0.01–0.07 nmol/L (3–20 pg/mL).

Reference ranges vary from country to country and between laboratories.

7. Causes of high testosterone

In women, high testosterone is most commonly caused by:

PCOS — by far the most common cause.
Adrenal hyperplasia or tumours (rare).
Ovarian tumours (rare).
Insulin resistance — high insulin reduces SHBG and increases free testosterone.
DHEA supplementation.
Anabolic steroid use.

8. Causes of low testosterone

Low testosterone in women is caused by:

Ageing — testosterone falls progressively from the late 20s.
Premature ovarian failure or surgical menopause.
High SHBG — from oral contraceptives, hyperthyroidism or pregnancy.
Adrenal insufficiency.
Vegetarian and vegan diets — research has shown lower testosterone in vegans.
Severe stress and chronic illness.

In men, low testosterone is caused by primary testicular failure (high LH/FSH), pituitary disease (low LH/FSH), age, obesity, alcohol, illegal drug use, sleep apnoea and chronic illness.

9. When and how to test testosterone

Testosterone is usually measured on day 2 or 3 of the menstrual cycle in women, alongside FSH, LH, oestradiol and SHBG. Total testosterone, free testosterone and SHBG together give a more complete picture than total testosterone alone, and the free androgen index (FAI = total testosterone × 100 / SHBG) is often calculated. Testosterone is highest in the morning, so morning testing is preferred.

Reference ranges vary from country to country. Always interpret your own result against the laboratory's reference range and discuss it with your doctor.

10. Testosterone in traditional Chinese medicine

In traditional Chinese medicine, testosterone most closely corresponds to Kidney Yang. Low testosterone in both men and women reflects Kidney Yang deficiency — symptoms of cold, fatigue, low libido, lower back ache, frequent urination and slow movements. High testosterone in women, particularly with PCOS, is most commonly seen as Damp-Phlegm with Liver Qi stagnation, on a background of Kidney Yang deficiency.

11. Acupuncture and testosterone

Acupuncture has been shown in research to:

Reduce elevated testosterone in women with PCOS.
Improve testosterone production in men with low testosterone.
Increase testicular blood flow and improve sperm production in men.

12. Chinese herbal medicine and testosterone

For low testosterone, Kidney Yang tonifying formulae such as You Gui Wan, Jin Gui Shen Qi Wan, Wu Zi Yan Zong Wan and Er Xian Tang are commonly used. Tribulus terrestris (sometimes used in TCM) has been shown to increase DHT levels and improve sperm production. For high testosterone in PCOS, formulae that resolve Damp-Phlegm and move Liver Qi such as Cang Fu Dao Tan Tang are used.

13. Diet, supplements and lifestyle

To support healthy testosterone levels:

Eat enough protein and healthy fats — testosterone is built from cholesterol.
Ensure adequate zinc (15 mg/day for women, up to 66 mg/day for men with low sperm count) — zinc is required for testosterone production.
Get adequate sleep — testosterone is produced overnight.
Reduce alcohol — alcohol suppresses testosterone in men.
Address insulin resistance to reduce high testosterone in PCOS.
For men, avoid heat to the testes (no laptops on the lap, no hot baths, no tight underwear).
Reduce psychological stress.