Sex Hormone Binding Globulin (SHBG)
SHBG — Trimester-Specific Reference Ranges
SHBG is a hepatic glycoprotein binding estradiol and testosterone. Rising estrogen during pregnancy markedly increases SHBG levels, peaking in mid–pregnancy.
| Measurement | 1st Trimester | 2nd Trimester | 3rd Trimester | Nonpregnant Female | Units |
|---|---|---|---|---|---|
| SHBG | 4.4 – 14.7 | 24 – 81 | 24 – 81.3 | 2 – 12.8 | µg/L |
| SHBG | 39 – 131 | 214 – 717 | 216 – 724 | 18 – 114 | nmol/L |
Physiologic changes in pregnancy
- Estrogen stimulation → ↑ hepatic SHBG synthesis.
- Progressive rise through pregnancy with plateau in late 3rd trimester.
- Higher SHBG → reduced free estradiol and testosterone fractions.
- Insulin resistance only partially blunts SHBG elevation.
Causes of high SHBG
- Pregnancy (physiologic)
- Hyperthyroidism
- Estrogen therapy / oral contraceptives
- Liver disease (hepatitis, cirrhosis)
- Low BMI / anorexia
- HIV infection
- Androgen deficiency
Causes of low SHBG
- PCOS
- Obesity
- Insulin resistance / metabolic syndrome
- Hypothyroidism
- Nephrotic syndrome
- Androgen excess (endogenous or exogenous)
- Glucocorticoid use
- Acromegaly
References
- Abbassi-Ghanavati M, Greer LG, Cunningham FG. Pregnancy and laboratory studies: a reference table. Obstet Gynecol. 2009;114:1326–1331.
- Hammond GL. Clinical relevance of SHBG. Clin Endocrinol. 2016.
- Rosner W et al. Pitfalls in measuring testosterone. J Clin Endocrinol Metab. 2007.
- Selva DM et al. Hepatic regulation of SHBG. J Clin Invest. 2007.
- Glintborg D, Andersen M. PCOS and SHBG. Eur J Endocrinol. 2017.
- Kershaw EE, Flier JS. Adipose tissue endocrinology. J Clin Endocrinol Metab. 2004.
- Kim TH et al. Liver disease and SHBG. Hepatology Int. 2018.