What Thyroid Tests Should I Request?

Your TSH level doesn’t always paint the full picture, so more testing may be necessary.


Besides T3, T4, and TSH, what other things should my doctor be testing for? Are there specific things I should ask them to test for that relate to my thyroid? Can they turn me down? Are these included with my insurance?


A basic thyroid panel consists of a thyroid stimulating hormone (TSH) test, as well as Free T4 and Free T3 tests, rather than “total” T4 and T3. The “free” levels of these thyroid hormones are considered more reflective of the available amounts of thyroid hormone circulating in your bloodstream. There are some other tests, however, that you may want to discuss with your doctor.

Thyroid antibodies tests — If you are hypothyroid (an underactive thyroid), you should ask for the thyroid peroxidase (TPO) antibodies test, sometimes abbreviated as TPOAb. This test can tell you if you have autoimmune Hashimoto's thyroiditis, the most common cause of hypothyroidism in the United States. If you are hyperthyroid, you should ask for a thyroid stimulating immunoglobulin (TSI) antibodies test. This test can diagnose autoimmune Graves' disease, the most common cause of hyperthyroidism. Having an autoimmune thyroid disease is important medical history information for you and your family because it puts you all at slightly higher risk of developing other autoimmune diseases. You can also pursue treatments that may lower your antibodies.

Reverse T3 test — If you are hypothyroid but still having symptoms such as fatigue, weight gain, and depression, consider asking for a reverse T3 (RT3) test. This test measures a form of T3 — your active thyroid hormone — that is not only inactive, but it blocks your body’s ability to use actual T3. If your RT3 is elevated, some doctors will consider adding — or increasing your dose of — a T3 medication like liothyronine (Cytomel) or natural desiccated thyroid.

Iodine test —If you are borderline or mildly hypothyroid, the cause may be an iodine deficiency. Your doctor can test for your iodine level — the urinary iodine clearance test is considered most accurate. If you are iodine deficient, supplementing with iodine may help your thyroid levels return to normal.

Ferritin test —Ferritin is a form of stored iron that is essential for proper hormonal balance as well as hair growth. If you are hypothyroid and still tired, or have any type of thyroid disease and are losing hair, consider asking for a ferritin test. Some experts recommend that your levels fall within the top 25th percentile of the reference range for optimal hormonal function and to counteract hormonal hair loss. If your levels aren’t optimal, supplementing with iron can help get them back to normal. But remember: If you are taking thyroid hormone replacement medication for hypothyroidism, you should take it at least three to four hours apart from any iron supplements, to avoid negatively affecting the absorption of your thyroid drugs.

Fasting glucose and hemoglobin A1C (HA1C) test — If you are having trouble losing weight, it's time to ask about fasting glucose and HA1C tests. The fasting glucose test measures your blood sugar after fasting, and the HA1C gives a two- to a three-month snapshot of your average blood sugar. If either or both levels are elevated, you may be insulin resistant and prediabetic. Treatment — which can include medication, a carbohydrate-controlled healthy diet, and exercise — may help you lose weight and prevent type 2 diabetes.

Whether or not your doctor is willing to run these tests depends in large part on the doctor. I recommend that you put together a one-page list of the symptoms prompting you to request the test, for review with your doctor. If the doctor refuses to run the tests, ask the doctor to sign and date the list, indicating that he or she has denied the requested tests. (Most doctors will grudgingly comply with your request to order the tests when asked to document their refusal.)

If your doctor still refuses, in most states, you can order them yourself using a direct-to-consumer laboratory like MyMedLab or HealthCheckUSA. These laboratories make tests available directly to consumers at discounted wholesale costs. In some cases, your insurance may even cover the cost.

The terms of your specific health insurance policy will dictate in large part whether the tests are covered. Some tests, such as fasting glucose, are included in standard bloodwork for an annual physical. In the end, however, it also depends on how your doctor “codes” the tests. For example, if you have hair loss, your doctor could potentially code a ferritin test as diagnostic for “alopecia” (the medical term for hair loss), and some insurance companies would cover the cost. Don’t be afraid to ask your doctor to argue on your behalf that a particular test is medically necessary.

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You should know: The answer above provides general health information that is not intended to replace medical advice or treatment recommendations from a qualified healthcare professional.

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