Sex Hormone Binding Globulin (SHBG) is an important protein that helps in reproduction and puberty. There are many factors that help regulate SHBG. Read below to learn more about this protein and its effects on the body.
Sex Hormone Binding Globulin (SHBG) is a glycoprotein encoded by a single gene on the short arm of chromosome 17 in humans (R).
The liver produces SHBG and circulates throughout the body (R).
The production of SHBG fluctuates throughout the life cycle. Metabolic and hormonal factors primarily influence its production (R).
The difference in SHBG levels can also be due to genetic differences (R).
SHBG in Adulthood
In adults, plasma SHBG levels vary between people (R).
The variance can be due to a number of factors, such as endocrine and metabolic rates. The differences could also be inherited (R).
Mutations, such as polymorphism, can cause variation as well (R).
For example, a common SNP that results in a D327N substitution increases the half-life of SHBG in blood and increase SHBG levels (R).
SHBG levels are higher in women than men. SHBG levels in men are about 50% of that in women (R).
The occupancy of steroid-binding sites in SHBG is different between the two sexes as well (R).
During pregnancy, SHBG levels increase 10-fold in women due to increased SHBG production in the liver (R).
Roles of Sex Hormone Binding Globulin
1) SHBG Aids Reproduction
Sex steroids or their immediate precursors are produced in the gonad, adrenal glands, and placenta and are transported to their target tissues in the blood via steroid-binding proteins (R).
During mid to late pregnancy, SHBG levels in the maternal plasma increase 5- to 10- fold (R).
2) SHBG Helps Regulate Puberty
SHBG levels start low in newborn babies and increase in infants of both sexes until puberty (R).
After puberty, SHBG starts to decline (R).
SHBG levels decline more in boys than in girls (R).
The reason for this might be due to androgens that suppress SHBG levels (R).
3) SHBG Might Protect Against Diabetes
Women with diabetes had significantly lower SHBG levels compared to individuals without diabetes (R).
However, men with diabetes had only slightly lower SHBG levels than non-diabetic controls (R).
The relationship between SHBG levels and T2DM may seem to be the result of SHBG altering the bioavailability of the sex hormones (R).
Regulation of SHBG
There is a large variation in SHBG levels among individuals (R).
There are many factors that affect SHBG levels in the blood of an individual (R).
In most cases, the mechanism by which these factors affect the SHBG levels are unknown (R).
Factors that Increase Level of SHBG in Blood:
- During pregnancy, SHBG levels increase 10-fold in women due to increased SHBG production in the liver (R).
- Weight Loss
- Alcoholic Cirrhosis
- HepB and C infections
- SHBG levels are significantly lower in patients with Hepatitis B or C infection (R).
- Growth Hormone Deficiency
Factors that Decrease Level of SHBG in Blood:
- Exogenous testosterone, a type of Androgen, has shown to decrease serum SHBG levels (R).
- Experiments suggest that insulin suppresses SHBG production in liver (R).
- Growth Hormone
- In response to a monosaccharide, SHBG levels are lowered (R).
- Metabolic Syndrome (R)
- Cushing’s Syndrome
- SHBG levels are lower in patients with Cushing’s Syndrome (R).
- Type 2 Diabetes Mellitus (R)
- Polycystic Ovary Syndrome
- SHBG levels are lower in patients with polycystic ovary syndrome, which results in higher amount of active androgen (R).
- Congenital Adrenal Hyperplasia
- Female patients with congenital adrenal hyperplasia have lower SHBG levels (R).
- The first is that Sex Hormone Binding Globulin directly participates in the delivery of steroid ligands to specific target cells (R).
- Secondly, SHBG itself acts as a ligand for a receptor (R).
- In women, only about 18% of the steroid-binding sites are occupied at serum concentrations, whereas about 56% of the sites are occupied by men (R).
- However, studies suggest that the relationship between SHBG and T2DM is independent of sex hormone levels (R).
- The exact mechanism by which SHBG influences risk of diabetes is unclear. However, SHBG and glucose metabolism impairment are linked together (R).
The information on this website has not been evaluated by the Food & Drug Administration or any other medical body. We do not aim to diagnose, treat, cure or prevent any illness or disease. Information is shared for educational purposes only. You must consult your doctor before acting on any content on this website, especially if you are pregnant, nursing, taking medication, or have a medical condition.
HOW WOULD YOU RATE THIS ARTICLE?