Sex Hormone Binding Globulin

Sex hormone binding globulin is a liver-produced glycoprotein that binds testosterone and oestradiol, leaving only the free fraction biologically active. Insulin suppresses hepatic SHBG production, which is why low SHBG is a marker of insulin resistance and predicts type 2 diabetes and metabolic syndrome. High SHBG accompanies hyperthyroidism, liver disease, ageing, oestrogen therapy and anticonvulsant use. Interpreting total testosterone without SHBG is a common clinical error: identical total values can mean very different free hormone availability. Treat the underlying driver rather than chasing the number.

1) Improve insulin sensitivity — losing visceral fat and reducing refined carbohydrate raises pathologically low SHBG toward normal. 2) Treat thyroid dysfunction; hyperthyroidism raises SHBG substantially and hypothyroidism lowers it. 3) Reduce alcohol, which alters hepatic protein synthesis and oestrogen metabolism. 4) Maintain adequate protein intake, since very low protein diets raise SHBG. 5) Review medications — oestrogens and some anticonvulsants raise it, while androgens, glucocorticoids and thyroid suppression lower it. 6) Always interpret SHBG alongside total testosterone and calculated free testosterone rather than in isolation. 7) Do not target SHBG directly with supplements; the number is a readout of metabolic and hepatic state.

• •Visceral fat reduction
• •Reduced refined carbohydrate intake
• •Alcohol moderation
• •Adequate protein intake
• •Thyroid management
• •Medication review