What the value means
Total testosterone includes hormone bound to SHBG, hormone loosely bound to albumin and a small free fraction that acts in the tissues. SHBG is reported in nmol/L, and its range differs by sex, age and laboratory. With high SHBG, it is worth calculating or measuring free testosterone. A value within the “normal” range is not automatically optimal – from a prevention perspective, what matters more is whether the results match how you feel.
Possible causes
- Age – SHBG rises naturally with age, so free testosterone falls faster than total testosterone.
- Overactive thyroid – an excess of thyroid hormones is a typical cause of high SHBG.
- Low energy intake and low body fat – long-term dieting, fasting without eating enough or marked weight loss raise SHBG.
- Liver and alcohol – liver disease and regular alcohol use often increase SHBG.
- Estrogens and medication – hormonal contraception, estrogen therapy or some anti-epileptic drugs increase SHBG production.
What you can do
- Add further tests – free testosterone (measured or calculated from total testosterone, SHBG and albumin), TSH and fT4, liver tests.
- Eat enough – adequate energy intake and enough protein; extreme diets and long fasts are better avoided.
- Cut down on alcohol – less alcohol benefits both the liver and hormonal balance.
- Strength training and sleep – they support testosterone production and recovery; excessive training volume without rest does the opposite.
- Measure consistently – draw blood in the morning while fasting, in the same laboratory – free testosterone calculations depend on the methods used.
When to see a doctor
See a doctor if you have signs of an overactive thyroid (palpitations, weight loss, sweating, tremor), signs of liver disease, or if low free testosterone comes with fatigue, reduced libido or fertility problems. Do not stop hormonal contraception or other medication on your own – discuss any change with your doctor.