Tests of thyroid function

Thyroid-Stimulating Hormone (TSH)

The TSH test is often the test of choice for evaluating thyroid function and/or symptoms of hyperthyroidism or hypothyroidism .

Thyroxine (T4) test is described here.

Triiodothyronine (T3) test is described here.

Different doctors do different variations of thyroid panel tests.

Thyroid stimulating hormone (TSH)

This protein hormone is secreted by the pituitary gland and regulates the thyroid gland. The TSH is an indicator of whether or not your thyroid is functioning properly. The TSH (thyroid stimulating hormone) is produced as a feedback mechanism from your pituitary gland.

When your body's under producing thyroid hormone, your pituitary signals the thyroid to produce more meaning if your TSH is elevated, you're not making enough thyroid hormone and replacement may be necessary.

If your TSH is low, that's an indicator that your body is either producing too much thyroid hormone or you're over medicated with thyroid replacement. A high level suggests your thyroid is underactive.

Frequent TSH levels are recommended especially while on the MP as your hormones will fluctuate during the healing process and proper dosage should be adjusted according to lab readings.

Free T4 and T3

The most informative thyroid function tests are the “free” tests since this gives you an indication of the usable thyroid hormone for use to your body. Free T4 (FT4) is the amount of available thyroxine in your body, which your body then converts to FT3 for metabolic functioning use.

Use Free T3 levels to check as well as Free T4 and TSH and permit the last two to be low if Free T3 is in mid normal range.

Thyroxine (T4) and triiodothyronine (T3) are easily measurable in the blood. For technical reasons, it is easier and less expensive to measure the T4 level, so T3 is usually not measured on screening tests.

Free T4

This test directly measures the free T4 in the blood rather than estimating it like the FTI. It is a more reliable , but a little more expensive test. Some labs now do the Free T4 routinely rather than the Total T4.

Total T3

This is usually not ordered as a screening test, but rather when thyroid disease is being evaluated. T3 is the more potent and shorter lived version of thyroid hormone. Some people with high thyroid levels secrete more T3 than T4. In these (overactive) hyperthyroid cases the T4 can be normal, the T3 high, and the TSH low. The Total T3 reports the total amount of T3 in the bloodstream, including T3 bound to carrier proteins plus freely circulating T3.

Free T3

This test measures only the portion of thyroid hormone T3 that is “free”, that is, not bound to carrier proteins.

The only concern you should have is to make sure that the supplement you are taking is not more than you need to keep your body functioning properly. As the thyroid function slowly returns, you will need to reduce your thyroid meds, and Doc can do the tests to help you with the weaning.

Please be clear on which test you are looking at. We continue to see a tremendous amount of confusion among doctors, nurses, lab techs, and patients on which test is which. In particular, the “Total T3”, “Free T3” and “T3 Uptake tests” are very confusing, and are not the same test.

Thyroxine (T4)

This shows the total amount of the T4. High levels may be due to hyperthyroidism, however technical artifact occurs when estrogen levels are higher from pregnancy, birth control pills or estrogen replacement therapy. A Free T4 (see below) can avoid this interference.

T3 Resin Uptake or Thyroid Uptake

This is a test that confuses doctors, nurses, and patients. First, this is not a thyroid test, but a test on the proteins that carry thyroid around in your blood stream. Not only that, a high test number may indicate a low level of the protein! The method of reporting varies from lab to lab. The proper use of the test is to compute the free thyroxine index.

Free Thyroxine Index (FTI or T7)

A mathematical computation allows the lab to estimate the free thyroxine index from the T4 and T3 Uptake tests. The results tell us how much thyroid hormone is free in the blood stream to work on the body. Unlike the T4 alone, it is not affected by estrogen levels.

You have most of what you need/want to know in the FT3, FT4 and TSH tests.

Adrenocorticotropic hormone (ACTH) test is described here.

ACTH levels in the blood are measured to help detect, diagnose, and monitor conditions associated with excessive or deficient cortisol in the body.

I am watching my thyroid antibody count drop as I progress on the MP. I've been on the MP for almost a year now. My Thyroid itself has been herxing, as the nasty bugs die and irritate the tissue,so the thyroid can't work as well, as I have noted at the start of each phase: my TSH (thyroid stimulating hormone = demand for thyroid to “produce more juice” ) jumped when I started phase I and again on phase II & III. That went along with pain and swelling in my throat and hair-loss, which was a hypothyroid symptom. Then it leveled out as my body progressed through the phases.

A chart of my TSH would show a spike each time, as herxing commenced, then return to normal. However, my thyroid antibodies count, which started “off the chart” has steadily declined throughout. From >1000 to something in the 200s. I look forward to seeing a big fat 'zero' one day. I know we officially “don't believe in autoimmunity” according to the MP theory, however the mainstream medical community does, and anything that can illustrate “recovery from autoimmunity” is useful as well as heartening.

The hair-loss is something I've come to expect and it grows back each time - giving an interesting natural “layered” effect! HaHaHa

Claudia

Regarding the thyroid. Having had both issues of hyper and hypo thyroid I would probably force my doc to run the following tests to see if I really had auto immune thyroid issues before he/she labeled me as such.

I would suggest that you try and get the following tests done to see exactly what type of thyroid issues you are dealing with.

Thyroid Antibodies: anti-TPO and TgAb will help discern Hashimotos. You need BOTH> You can add TSI (thyroid stimulating immunoglobulins) for the Graves antibodies–some have all three.

I would also have them check the TRab (Thyrotropin Receptor Ab) sometimes this is called the TBII test. This will help show if there are any blocking antibodies for Graves. Which can trick the results into thinking you are hypothyroid. The TSI are the stimulating antibodies and the TRab are the blocking antibodies in Graves (hyper thryoid). From the looks of your labs it is possible that you do have hashimotos but I'd want to know the whole story. Your Free T4 is in mid range which can be argued as the best indicator of how well the thyroid is working. I also would like to see the Free T3 as well to see how well your body converts T4 into T3 which is the usable form of the hormone.

They may say you don't have graves you have hashimotos but people can have both. It is also possible that you have/had a nodule on your thyroid that is responsible for the hyper experiences but the hypo situations most of the time. This could be diagnosed with a thyroid ultrasound.

One thing I have learned about doctors especially endocrinologists is that most of them don't know squat about the thyroid. They are too busy with the diabetic patients.

Feel free to post the results if you get them I'll try my best to help you interpret them. Unfortunately, I have gotten pretty good at reading them over the past 3 years.

Hogan

Reminds me of the TSH test:they are addicted to it for detecting a thyroid problem. No abnormal TSH, you don't have any thyroid disorder-see a psychiatrist. I use Lugol's Solution diluted by about 20 times to keep thyroiditis symptoms at bay. Not every day, usually once every 10 days or so. Yet, according to them, I don't have a thyroid disorder(!). When the Hashimoto's first showed up some decades ago, I had a 1:100 titer antithyroid antibody. There are so many antithyroid antibodies in several different immunoglobulin families that no tests are available for. You have antibodies but they don't know they exist, no test available even in the research laboratories, so therefore you need a psychiatrist (The psychologists and psychiatrists I consulted in the past have unanimously sent me straight back to the physical medical system as I don't have any psychological issues at all in their opinion.)

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