Sex hormone-binding globulin (SHBG)
HormonesAlso known as: sex steroid binding globulin, SSBG, androgen binding globulin
A glycoprotein that regulates hormone bioavailability by binding to sex hormones in circulation.
SHBG levels influence the amount of active hormones available to tissues and can reflect metabolic and endocrine health.
Why this matters
SHBG levels reveal how much active sex hormone is available and can indicate hormonal imbalances. Low SHBG may be linked to insulin resistance, obesity, or metabolic issues, while high SHBG can reduce the availability of sex hormones, affecting reproductive and metabolic health. Maintaining a healthy weight, balanced diet, and regular exercise can help support normal SHBG levels and overall hormone balance.
How this connects to other biomarkers
- Low SHBG with elevated HOMA-Index, Fasting Insulin, and central obesity is a hallmark of insulin resistance and increases biologically active androgen (high Free Androgen Index (FAI)) — common in PCOS (polycystic ovary syndrome).
- High SHBG can lower active testosterone despite normal Testosteron, total, contributing to symptoms of low testosterone (use Testosteron, free to clarify).
- Elevated SHBG can be seen in overactive thyroid (suppressed TSH), liver disease, and oral estrogen therapy.
How often should I test Sex hormone-binding globulin (SHBG)?
Most adults benefit from checking SHBG once a year alongside testosterone or estradiol. After a meaningful change in body composition or metabolic health, retest at 8 to 12 weeks.
At baseline / for screening: Once every 12 months from age 30 as part of a hormone panel.
When monitoring an intervention or change: Retest 8 to 12 weeks after a sustained metabolic or body composition change. Low SHBG is a sensitive early marker of insulin resistance and shifts with metabolic improvement. After starting or adjusting hormone therapy (testosterone, estrogen, thyroid), retest at 6 to 12 weeks. High SHBG can reflect hyperthyroidism, liver disease, or estrogen therapy.
Note: SHBG rises with thyroid hormone, oral estrogen, and certain seizure medications, and falls with insulin resistance and androgens. After meaningful changes in any of these, wait 8 to 12 weeks before reading the next value as a stable baseline.
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