What is SHBG?
Sex hormone binding globulin is a protein which is produced by liver. It binds & transports 3 sex hormones i.e. dihydrotestosterone or DHT (an androgen, male sex hormone), testosterone (androgen, male sex hormone), & estradiol (estrogen, female sex hormone) in blood in both men and women as biologically inactive forms. In men, testosterone of 45% to 65% is bound to SHBG in blood, with remainder weakly bound to albumin (main protein in blood). In women, testosterone is 66% to 78% more bound to SHBG. SHBG plays a significant role in regulating bioavailable male sex hormones (androgen) & estrogen levels in women.
What is SHBG lab test?
This laboratory test measures level of SHBG (sex hormone binding globulin) in blood. As mentioned above, SHBG controls how these 3 hormones are delivered in body tissues. But mostly SHBG test is used to look at testosterone hormone i.e. it looks if too much or too little testosterone is being used by the body. As too little testosterone in male & too much testosterone in female leads to problem. SHBG levels in blood change due to factors like sex, age, obesity, liver disease & hyperthyroidism.
Why is SHBG lab test done?
The test is done:
- To look for SHBG hormone based illnesses.
- Evaluate when experience symptoms in men for low testosterone & women for too much testosterone production
- With other tests helps evaluate status of person’s sex hormones.
- In men, total testosterone level helps to determine cause of infertility, decreased sex drive, erectile dysfunction (inability to achieve/sustain an erection)
- In women, to detect & evaluate excess testosterone production, decreased SHBG concentration, and in PCOS suspected women.
- Is fasting required for SHBG blood test?
It is also known as testosterone-binding globulin & it requires fasting.
- What does high & low SHBG mean?
Its high SHBG level means less free testosterone is available to tissues. Low levels of SHBG show that more of total testosterone is bioavailable and not bound.
- Which factors cause high SHBG in females?
Higher than normal SHBG in females happen due to oral contraceptives, undernourishment, anorexia nervosa (eating disorder), and estrogen or thyroid hormone treatment.
- What are ways by which you can increase SHBG?
Studies suggest that SHBG can be increased through exercise, drinking coffee, certain oral contraceptives, increase fiber, decrease sugar in diet, loosing weight, & taking supplements.
- Are SHBG levels increased with estrogen?
Estrogenic states in the form of oral contraceptives can increase SHBG levels.
INTERPRETATION OF THE RESULTS:
SHBG ranges in male:
- 20-49 years: 16.5 to 55.9 nmol/L
- Greater than 49 years: 19.3 to 76.4 nmol/L
SHBG ranges in females
- 20-49 years: 24.6 to 122.0 nmol/L
- Greater than 49 years: 17.3 to 125.0 nmol/L
Its decreased levels seen in:
- Hirsutism (women with excessive growth of dark/ coarse hair in male-like pattern face, chest and back)
- Virilization (women develop male-pattern hair growth and other masculine physical traits)
- Obese postmenopausal women
- Women with diffuse hair loss
Its increased levels seen in:
- Hyperthyroidism (overactive thyroid)
- Testicular feminization (androgen insensitivity syndrome)
- Cirrhosis (late stage of scarring of the liver)
- Male hypogonadism (body doesn't produce enough of the hormone that plays key role in masculine growth and development during puberty)
- Pregnancy
- Oral contraceptive use in women
- Prepubertal children (occurs in lower genital tract)
You get tested as it measures and evaluates low testosterone (possible androgen deficiency) in males, and women with signs & symptoms suggesting excess androgens.