Skip navigation | ||
|
||
Medical Encyclopedia |
|
Other encyclopedia topics: | A-Ag Ah-Ap Aq-Az B-Bk Bl-Bz C-Cg Ch-Co Cp-Cz D-Di Dj-Dz E-Ep Eq-Ez F G H-Hf Hg-Hz I-In Io-Iz J K L-Ln Lo-Lz M-Mf Mg-Mz N O P-Pl Pm-Pz Q R S-Sh Si-Sp Sq-Sz T-Tn To-Tz U V W X Y Z 0-9 |
Contents of this page: | |
|
Alternative names Return to top
Serum thyroxine binding globulin; TBG levelDefinition Return to top
Serum TBG level is a test to evaluate thyroid function by measuring the level of thyroxine binding globulin (TBG) in the blood. Thyroxine binding globulin is a protein that transports thyroid hormone around your body.How the test is performed Return to top
Blood is drawn from a vein, usually on the inside of the elbow or the back of the hand. The area where blood is to be drawn is cleaned with antiseptic, and a tight elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.
A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Once the blood has been collected, the band is removed to restore circulation, the needle is removed, and the puncture site is covered to stop any bleeding.
The sample is then taken to the laboratory where it is evaluated by special laboratory tests, such as electrophoresis or radioimmunoassay.
How to prepare for the test Return to top
Several medications and conditions can interfere with TBG test results.
If you take any of the following, your TBG results may be elevated:
If you have one of the following conditions, your TBG results may also be elevated:
If you take any of the following, your TBG levels may be reduced:
If you have one of the following conditions, your TBG results may also be reduced:
If you take any of these medications, or have any of these conditions, inform your doctor before the test, since you may need to withhold your medication, or have another test.
If your child is to have this test performed it may be helpful to explain how the test will feel, and even practice or demonstrate on a doll. The more familiar your child is with what will happen to him/her, and the purpose for the procedure, the less anxiety he/she will feel.
How the test will feel Return to top
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.Why the test is performed Return to top
Your doctor may use this test to identify abnormalities with your thyroid binding globulin, or to assist in diagnosing other thyroid disorders such as hypothyroidism.Normal Values Return to top
Normal values vary somewhat from laboratory to laboratory, and depend on which method is used to evaluate the sample. If electrophoresis is used, results are reported in terms of T4 binding capacity (the binding capacity of the thyroid hormone T4), and normal values may range from 10 mcg/100 ml to 24 mcg/100 ml.What abnormal results mean Return to top
Other than problems with your thyroid gland, elevated TBG levels may indicate:What the risks are Return to top
Risks associated with having blood drawn are slight:Special considerations Return to top
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others. Update Date: 9/3/2003 Updated by: Michael C. Milone, M.D., Ph.D., Department of Pathology and Laboratory Medicine, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network.
Home | Health Topics | Drug Information | Encyclopedia | Dictionary | News | Directories | Other Resources | |
Copyright | Privacy | Accessibility | Selection Guidelines U.S. National Library of Medicine, 8600 Rockville Pike, Bethesda, MD 20894 National Institutes of Health | Department of Health & Human Services |
Page last updated: 28 October 2004 |