Sex Hormone Binding Globulin
also known as SHBG
/WHAT_IT_IS
SHBG is a liver-made protein that tightly binds testosterone (and estradiol) in the bloodstream, regulating how much is biologically available. It's the single biggest determinant of your free testosterone after total T itself.
/NORMAL_RANGE
Adult male reference is roughly 10–57 nmol/L. Optimal levels for men on TRT typically sit in the 20–40 nmol/L range — high enough to buffer aromatization, low enough to allow meaningful free T.
What does high SHBG mean?
- +Aging — SHBG rises ~1% per year after 40.
- +Hyperthyroidism, liver disease, anorexia or chronic calorie deficit.
- +Oral estrogens or anti-androgens.
- +Genetically high SHBG — some men just have it.
What does low SHBG mean?
- +Obesity, insulin resistance, fatty liver, metabolic syndrome.
- +Hypothyroidism, Cushing's, anabolic steroid use.
- +Genetics — some men have constitutively low SHBG.
/ON_TRT
SHBG is the lever most men on TRT need to actually move to feel right. High SHBG means your free T is lower than your total T suggests — splitting your weekly dose into 2–3 smaller injections helps. Low SHBG means free T runs disproportionately high relative to total T, and you may need a lower total weekly dose than guidelines suggest. SHBG tends to drop with longer-acting esters and rise with daily / EOD dosing — sometimes counterintuitively.
/RELATED
FAQ
/01What is the ideal SHBG level for men on TRT?+
Most TRT clinicians target 20–40 nmol/L. Too high (>50) and free T gets squeezed; too low (<15) and you may need to cut total testosterone to avoid symptoms of androgen excess.
/02How do I lower SHBG?+
Address insulin resistance (lose visceral fat, improve fasting glucose), treat hypothyroidism if present, reduce alcohol, and ensure adequate protein intake. Some clinicians also use boron supplementation though evidence is mixed.
/03How do I raise SHBG if it's too low?+
Lose body fat, address fatty liver, increase fiber, and ensure thyroid function is normal. Some men also benefit from splitting their TRT into more frequent, smaller injections — which paradoxically can raise SHBG over time.
Track SHBG in the app.
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