Lexicon
SHBG
Also known as Sex hormone-binding globulin
Definition
Human sex hormone-binding globulin is a glycoprotein produced by the liver that binds sex steroids with high affinity and specificity. [1] Testosterone circulates both in free form and bound to protein including albumin and SHBG, whose levels are an important determinant of the free testosterone concentration. [2]
How it works
Steroids are predominantly bound to plasma proteins and only unbound steroids enter cells, so changes in SHBG concentration exert significant effects on hormone action. [3] Increased SHBG levels raise estrogen action and decrease testosterone activity, whereas increased androgens increase testosterone action and inhibit SHBG production. [3] Compensatory hyperinsulinemia contributes to hyperandrogenism partly by inhibiting hepatic sex hormone-binding globulin production, and decreased SHBG increases the bioavailability of androgens. [4] [1]
Connected concepts
How it's measured
In men whose total testosterone is near the lower limit of normal or who have a condition that alters SHBG, the Endocrine Society recommends obtaining a free testosterone concentration using equilibrium dialysis or estimating it with an accurate formula. [5] Serum SHBG has been proposed as a useful diagnostic biomarker and therapeutic target for managing women with polycystic ovary syndrome. [1]
What levels mean
In a reported polycystic-ovary-syndrome case, a serum SHBG concentration of only 8 nmol/L was well below the stated normal range of 20 to 118 nmol/L, illustrating the low SHBG typical of the condition. [1] Emerging evidence suggests that low hepatic SHBG production may be a key step in the pathogenesis of PCOS and correlates negatively with markers of non-alcoholic fatty liver disease and insulin resistance. [1] Very low serum SHBG together with unexplained erythrocytosis is a clue to anabolic androgenic steroid use, reflecting exogenous androgen suppression of SHBG. [6]
Community knowledge
## Interpreting SHBG & Free Testosterone
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- 1.Qu X, Donnelly R. Sex Hormone-Binding Globulin (SHBG) as an Early Biomarker and Therapeutic Target in Polycystic Ovary Syndrome. Int J Mol Sci · 2020
- 2.Burger HG. Androgen production in women. Fertil Steril · 2002
- 3.Anderson DC. Sex-hormone-binding globulin. Clin Endocrinol (Oxf) · 1974
- 4.Goodarzi MO, Dumesic DA, Chazenbalk G, Azziz R. Polycystic ovary syndrome: etiology, pathogenesis and diagnosis. Nat Rev Endocrinol · 2011
- 5.Bhasin S, Brito JP, Cunningham GR, Hayes FJ, Hodis HN, Matsumoto AM, Snyder PJ, Swerdloff RS. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab · 2018
- 6.Anawalt BD. Diagnosis and Management of Anabolic Androgenic Steroid Use.
Community discussion
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