SHBG

The IDS SHBG assay is an in vitro diagnostic device intended for the quantitative determination of SHBG in human serum or plasma on the IDS-iSYS Multi-Discipline Automated System.

Results are to be used as an aid in the diagnosis of androgen disorders.

Sex hormone binding globulin (SHBG) is a glycoprotein responsible for blood transport of testosterone and estradiol. SHBG production is regulated by the androgen/estrogen balance, insulin levels, thyroid hormones and diet¹.

SHBG binds some androgens and estrogens and with high affinity², which prevents them being accessible to tissue, providing they remain bound to SHBG³. SHBG levels do not demonstrate diurnal variation⁴.

Compared with males, females have naturally higher levels of SHBG due to the presence of higher estrogen concentrations. In pregnancy, SHBG levels increase significantly as a result of the elevated estrogen production. Many conditions of mild-to-moderate androgen excess in women, particularly polycystic ovarian syndrome, are associated with low SHBG levels.

Suppressed levels of SHBG are associated with hypothyroidism, obesity, Cushing’s syndrome and acromegaly. Studies indicate that low SHBG levels may be an indicator of diabetes risk⁵ and that SHBG levels could be used as a biomarker for prediction of gestational diabetes risk⁶.

SHBG levels are commonly used together with a measurement of total testosterone (TT) in order to calculate the free androgen index (FAI); or, in place of direct measurement of free testosterone (FT) by immunoassay or equilibrium dialysis, FT levels can be calculated following the measurement of SHBG, TT and serum albumin. It is only free testosterone that is biologically active and therefore the best estimation of the clinical situation of an individual.

1. Burtis CA, Ashwood ER, Bruns DE. Tietz textbook of clinical chemistry and molecular diagnostics. Saunders, 2006. p. 2011-2012.
2. Dunn JF, Nisula BC, Rodbard D. Transport of steroid hormones: binding of 21 endogenous steroids to both testosterone-binding globulin and corticosteroid-binding globulin in human plasma. J Clin Endocrinol Metab 1981;53:58–68.
3. Siiteri PK, Murai JT, Hammond GL, Nisker JA, Raymoure SJ, Kuhn RW. The serum transport of steroid hormones. Recent Prog Horm Res 1982; 38:457–510.
4. Jin Z, Guan X, Gao H, Shang L, Gao M, Su D, Li W. The change in sex hormone binding globulin and the influence by gestational diabetes mellitus in fetal period. Gynecol Endocrinol 2009;25:647-652.
5. Ding EL, Song Y, Manson JE, Hunter DJ, Lee CC, Rifai N, Buring JE, Gaziano JM, Liu S. Sex hormone-binding globulin and risk of type 2 diabetes in women and men. N Engl J Med. 2009 Sep 17;361(12):1152-63.
6. Tawfeek MA, Alfadhli EM, Alayoubi AM, El-Beshbishy HA, Habib FA; BMC Womens Health. 2017 Mar 9;17(1):18.