Quick Facts
- Sample: Blood
- Fasting: No special preparation required
- Turnaround: 6-10 days. May take longer based on weather, holiday, or lab delays.
What This Test Measures
This test measures Corticosteroid-Binding Globulin (CBG), also known as transcortin, a protein found in the blood. CBG is not cortisol itself. It is a binding protein that transports cortisol and other steroid hormones, such as progesterone and testosterone, through the bloodstream to the cells and tissues where they are needed.
Because CBG is a carrier protein rather than cortisol, this test reflects how much binding capacity is available in the blood, not how much cortisol the adrenal glands are producing. The result gives your healthcare provider one piece of information related to cortisol transport, which is typically considered alongside other clinical findings when evaluating cortisol-related conditions.
Benefits
- Measures CBG, the protein that transports cortisol in the blood
- Supports evaluation of conditions linked to cortisol regulation
- May help monitor treatment for cortisol-related conditions
- Can assist in evaluating adrenal gland function alongside other findings
- Uses a simple blood sample with no special preparation
Who Is This Test For?
- Individuals with symptoms associated with Cushing's syndrome
- Individuals with symptoms associated with Addison's disease
- People being monitored for treatment of a cortisol-related condition
- People whose healthcare provider wants to evaluate adrenal gland function
- Individuals with symptoms potentially related to liver, kidney, or thyroid conditions affecting cortisol levels
How It Works
- Order Your Test Online
- Visit a Local Lab
- Get Results Online
FAQ
1. What is the purpose of this hormone test?
This test measures the level of Corticosteroid-Binding Globulin (CBG) in your blood. CBG, also known as transcortin, is a protein that binds and transports cortisol, along with other steroid hormones like progesterone and testosterone, through the bloodstream. It is not a measurement of cortisol itself, but rather reflects how much binding capacity is available in the blood. Your healthcare provider may use this result, along with other clinical information, to help evaluate cortisol-related conditions such as Cushing's syndrome or Addison's disease, or to assess adrenal gland function. This test alone does not diagnose a condition.
2. Who should consider this test, and when?
This test may be considered by individuals experiencing symptoms associated with Cushing's syndrome, such as weight gain or high blood pressure, or symptoms associated with Addison's disease, such as fatigue or low blood pressure. It may also be appropriate for people being monitored for treatment of a cortisol-related condition, those whose healthcare provider wants to evaluate adrenal gland function, or individuals with symptoms potentially related to liver, kidney, or thyroid conditions affecting cortisol levels. Your healthcare provider can help determine whether this test fits your specific situation.
3. How does this test differ from other hormone tests?
Unlike tests that measure cortisol or another steroid hormone directly, this test specifically measures CBG, the binding protein that transports these hormones through the blood. The level of CBG is distinct from the level of cortisol itself, so a CBG result does not indicate how much cortisol the adrenal glands are producing and should not be interpreted as a direct cortisol measurement.
4. Do I need to fast before this test?
No special preparation is required before this test.
5. How quickly will I get results?
Results are typically available in 6-10 days. Turnaround may take longer based on weather, holiday, or lab delays.
6. How do I interpret the results?
Interpreting your CBG result depends on your individual symptoms, medical history, and other laboratory findings. Because CBG is a binding protein rather than cortisol itself, results are often considered alongside other cortisol-related measurements and clinical information. An abnormal CBG result does not automatically confirm a cortisol-related condition, and a normal result does not automatically rule one out. Your healthcare provider is best positioned to interpret this result in the context of your overall health.
Disclaimer: Reference ranges may vary by laboratory. Listed ranges are general guidelines and may differ from those used by the performing lab. Always consult your healthcare provider for interpretation.
7. What should I do if my results are abnormal?
Review abnormal results with a qualified healthcare provider, who can help determine whether additional evaluation or testing may be appropriate based on your symptoms and health history. Do not attempt to interpret or act on abnormal results without professional guidance.
8. How often should I get tested?
Testing frequency should be determined as directed by your healthcare provider, based on your individual health needs and the purpose for which the test was ordered.
Pre test preparation
No special preparation required.
