SHBG: Sex Hormone Binding Globulin – BC286
Hormonal Balance TestReport: Next day Evening (Except Sunday)
Sample Type: Blood (Serum)
Test Code: BC286
The Sex Hormone Binding Globulin (SHBG) test measures the level of a protein produced mainly by the liver that binds tightly to sex hormones, primarily Testosterone, Dihydrotestosterone (DHT), and Estradiol. SHBG regulates the amount of these hormones that are freely circulating and biologically active in the bloodstream.
✔ Helps evaluate the status of "free" or active Testosterone and Estrogen.
✔ Crucial in investigating symptoms of hormone excess or deficiency when total hormone levels are borderline or normal.
✔ Aids in diagnosing conditions like PCOS, hypogonadism, and thyroid disorders.
✔ No fasting is typically required, but check with your doctor.
SHBG: The Hormone Transporter and Regulator
Think of SHBG as a taxi service for your sex hormones. Most of the testosterone and estrogen circulating in your blood is bound to SHBG (and to a lesser extent, albumin). Only the small fraction that is not bound (the "free" hormone) can actually enter cells, bind to receptors, and exert its biological effects (like influencing libido, muscle mass, or mood).
The level of SHBG itself can significantly impact your hormonal health. If SHBG levels are very high, it binds up more hormone, leaving less free hormone available for your tissues to use. This can lead to symptoms of hormone deficiency even if your total hormone levels appear normal. Conversely, if SHBG levels are very low, more hormone is left in the free, active state, which can lead to symptoms of hormone excess.
Why is the SHBG Test Ordered?
A doctor typically orders an SHBG test alongside Total Testosterone or Estradiol tests when:
- Symptoms of hormone imbalance (like low libido, fatigue, hirsutism, infertility) don't match the total hormone levels.
- To help calculate or estimate the level of Free Testosterone (sometimes called the Free Androgen Index or FAI).
- To investigate conditions known to affect SHBG levels, such as:
- High SHBG Causes: Liver disease, hyperthyroidism, certain medications (like anticonvulsants, estrogens), aging, low body weight.
- Low SHBG Causes: Obesity, insulin resistance/Type 2 Diabetes, hypothyroidism, Polycystic Ovary Syndrome (PCOS), Cushing's syndrome, use of anabolic steroids.
Measuring SHBG provides a more complete picture of your true hormonal status than measuring total hormone levels alone.
Frequently Asked Questions (FAQ)
SHBG (Sex Hormone Binding Globulin) is a protein made by your liver that binds to sex hormones like testosterone and estrogen in your blood, controlling how much of these hormones are available to your body's tissues.
It helps regulate the amount of "free" or active sex hormones. High SHBG means less active hormone, potentially causing deficiency symptoms even with normal total levels. Low SHBG means more active hormone, potentially causing excess symptoms.
To get a better understanding of your active testosterone level. If your Total Testosterone is normal but you have symptoms of low T, a high SHBG level could be the reason, as it leaves less free testosterone available. The SHBG level helps calculate or estimate your free testosterone.
Low SHBG is commonly seen in conditions associated with insulin resistance, such as obesity, Type 2 Diabetes, and PCOS. Hypothyroidism and the use of certain steroids can also lower it.
Fasting is generally not required for the SHBG test itself. However, it is often ordered as part of a larger hormone panel for which fasting might be recommended. Please confirm with your doctor or the lab.