Hormones
Sex Hormone Binding Globulin
What This Marker Tells Us
A protein that binds and transports sex hormones (testosterone, estrogen) in blood, determining how much hormone remains free and biologically active.
Why It Matters
Only free (unbound) sex hormones can enter cells and exert effects; SHBG-bound hormones are inactive. SHBG levels dramatically affect hormone activity: high SHBG binds more hormone, reducing free active hormone despite normal total levels. Low SHBG increases free hormone, amplifying effects even with normal total levels. Low SHBG is strongly associated with insulin resistance, metabolic syndrome, and type 2 diabetes; it's one of the earliest metabolic markers to change. High SHBG occurs with estrogen states, hyperthyroidism, liver disease, or aging. In men, low SHBG with normal total testosterone may cause low free testosterone, requiring SHBG measurement to calculate free testosterone accurately. SHBG is essential for interpreting total testosterone.
How to Interpret Your Trends
Optimal SHBG varies by sex and age. For men, roughly 20-60 nmol/L is typical, with lower values suggesting metabolic dysfunction. For women, approximately 20-130 nmol/L depending on menopausal status and hormones. Low SHBG (below 20 nmol/L in men, below 30 nmol/L in women) strongly suggests insulin resistance, metabolic syndrome, obesity, or hypothyroidism. Very low SHBG (below 15 nmol/L) indicates significant metabolic dysfunction. High SHBG (above 60 nmol/L in men, above 130 nmol/L in women) may indicate hyperthyroidism, liver disease, estrogen therapy, or aging. SHBG tends to increase with age and decline with metabolic dysfunction.
What Influences This Marker
SHBG decreases with insulin resistance, metabolic syndrome, obesity (especially visceral fat), hypothyroidism, growth hormone excess, androgens, and certain medications (steroids, phenytoin). SHBG increases with estrogen therapy, hyperthyroidism, liver cirrhosis, aging, very-low-calorie diets, and medications (anticonvulsants). Weight loss improves low SHBG. Improving insulin sensitivity through diet, exercise, and weight loss raises SHBG toward optimal levels.
How Your Team Uses It
Your coach addresses low SHBG through metabolic health optimization and strategies proven to improve insulin sensitivity including weight loss (especially visceral fat), resistance training, reduced refined carbohydrates, increased fiber intake, and improved sleep. For high SHBG, they ensure adequate protein and calorie intake, avoiding excessive restriction.
Related Signals We Also Review
Total testosterone, calculated free testosterone, insulin, glucose, HbA1c, thyroid panel, liver enzymes, and body composition for complete hormone and metabolic assessment.