SHBG blood test
This test measures the level of sex hormone binding globulin (SHBG) in your blood. SHBG is a protein made by your liver. It binds tightly to three sex hormones found in both men and women: estrogen; dihydrotestosterone, or DHT; and testosterone. SHBG carries these three hormones throughout your blood.
Although SHBG binds three hormones, the hormone that's critical in this test is testosterone. SHBG controls the amount of testosterone that your body tissues can use. Too little testosterone in men and too much testosterone in women can cause problems. The level of SHBG in your blood changes because of factors such as sex and age. It can also change because of obesity, liver disease, and hyperthyroidism.
You may have this test if your doctor suspects that you have abnormal testosterone levels. The test can help diagnose various conditions and diseases, including:
Androgen deficiency. The hormone androgen causes general weakness and sexual problems in men. In women, androgen may help with thinking and bone strength. It may also help the ovaries working the way they should.
Hypogonadism. This condition occurs mostly in men. It is found in men with low testosterone and low sperm production.
Your doctor will likely also order total testosterone blood test. This is because SHBG levels tend to change. Both the SHBG and total testosterone tests are needed to confirm an androgen deficiency.
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.
Low levels of SHBG can be related to:
Type 2 diabetes
Acromegaly, or too much growth hormone, causing body tissues grow larger over time
High levels of SHBG can be related to:
Anticonvulsants, or medicine used to treat seizures
The test requires a blood sample, which is drawn through a needle from a vein in your arm.
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.
Pain killers called opiates, medications for the central nervous system, and recreational drugs can all affect your test results. Having an eating disorder or engaging in excessive, strenuous exercise can also affect your results.
You don't need to prepare for this test. But be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.