
January 25, 2000
Diagnosis and Symptoms
Question from Bend, Oregon, USA:
My antiGAD test came back at 6.3. Is this low? What thyroid antibodies should I have checked?
Answer:
There is such a wide variation in the way different laboratories express anti GAD levels that you will have ask your doctor for the answer to this question. Most clinics do not measure thyroid antibodies because it is easier, less expensive and just as clinically useful to do a TSH (Thyroid Stimulating Hormone) test. You might ask though about the possible justification for an antitransglutaminase test for the celiac syndrome and an anti 21hydoxylase test for latent adrenal insufficiency.
DOB
Additional comments from Dr. Tessa Lebinger:
The most common anti-thyroid antibodies are anti-thyroglobulin and anti-peroxidase (formerly called anti-microsomal). Although the TSH test is the most sensitive to detect early hypothyroidism, I still do antibody testing, as often these tests will be positive even before the TSH is elevated, indicating an ongoing inflammation of the thyroid. Many doctors will start thyroid hormone replacement if the thyroid is enlarged and antibodies are positive even if the TSH is still normal.
TSH is a hormone made by the pituitary which stimulates the thyroid gland to make thyroid hormones. As the thyroid gland is starting to fail, the level of thyroid hormones may still be normal, but the TSH elevated, indicating that the pituitary is “pushing” the thyroid gland harder to keep up with normal production of thyroid hormones.
TGL