SHBG (Sex Hormone Binding Globulin) Test

Doctors order an SHBG test to people who show symptoms of abnormal testosterone levels. Usually, in such cases, a total testosterone test is enough to make a diagnosis. However, some people may have symptoms of too much or too little testosterone that cannot be explained by the total testosterone test. In such instances, the doctor may order an SHBG test. 

For a man, this test may be ordered when he shows the following symptoms related to low testosterone levels:

• Difficulty getting an erection
• Low sex drive
• Fertility problems

For a woman, this test may be ordered if she has the following symptoms of high testosterone levels:

• Excess facial and body hair growth
• Menstrual irregularities
• Acne
• Weight gain
• Fertility problems
• Deepening of voice

You do not require any preparations for this test. Fasting is not required either. Discuss with your doctor about any prescribed, non-prescribed or illicit medicines, vitamins and supplements you may be taking. Certain medicines, such as opiates and biotins, can affect the results of this test. 

Also, a high concentration of biotin may cause falsely decreased levels of SHBG. Therefore, this test should be done at least 12 hours after the last dose of biotin. 

Do not perform excessive strenuous exercise before the test. Inform your doctor if you have an eating disorder.

The SHBG test is performed on a blood sample. The required amount of blood will be drawn from a vein in your arm. 

If you are afraid of needles or the sight of blood, it may be helpful to look away or talk to someone to distract yourself. You may experience mild pain when the needle is pricked, but this will subside soon. If you notice a persistent bruise or infection at the blood withdrawal site, talk to your doctor at the earliest.

Result of this test may vary based on your age, sex, health history and the method of testing. High SHBG levels are seen during pregnancy due to increased oestrogen. Children of both sexes normally have high SHBG levels. After sexual maturation, the levels drop faster in boys than in girls. SHBG levels remain stable in adults but they gradually increase in men after a certain age. On the other hand, women start to show decreased SHBG after menopause.

Please consult your healthcare practitioner to know exactly what the results mean for you.

Normal results:

The reference range for males and non-pregnant females is as follows:

• Males: 10-80 nmol/L (nanomoles per litre)
• Females (non-pregnant): 20-130 nmol/L

Values during pregnancy are as follows:

• First trimester: 39 - 131 mmol/L
• Second trimester: 214 -717 mmol/L
• Third trimester: 216 - 724 mmol/L

Abnormal results:

A low level indicates that the SHBG is not binding to enough testosterone. This may result in more unbound testosterone in the blood and excess testosterone available for body’s tissues.

Low SHBG levels (and hence excess testosterone) may be seen in the following conditions:

• Hypothyroidism (low thyroid hormone)
• Type 2 diabetes
• Obesity
• Overuse of steroid medications
• Cushing's syndrome (a disorder caused by excess cortisol hormone)
• Cancer of the adrenal glands or testicles in men
• Polycystic ovary syndrome (PCOS) in women
• Acromegaly (a condition in which excess growth hormone causes body tissues to grow larger)

High levels of SHBG indicate that the protein is binding to too much testosterone, resulting in less unbound testosterone in the blood and not enough testosterone available to the tissues. High SHBG levels occur due to:

• Hepatitis
• Hyperthyroidism (increased thyroid hormone)
• Eating disorders
• HIV
• Medicines used to treat seizures 
• Birth control pills
• Liver disease such as cirrhosis 
• Problems related to the testicles or pituitary gland in men
• Problems related to the pituitary gland or Addison disease (reduced cortisol production) in women

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.