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Posted in: Hypothyroidism.

thyroid blood tests

From: oldie - 8 years 41 weeks ago

I'm confused by the arguments of those who say TSH, T3, T4 are sufficient to measure dosis of levothyroxine and those who insist that the real test is Free T3 and free T4, or that TSH should be abandoned in favour of these last two.. Any answers please

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6 Responses

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According the the American Thyroid Association, currently there are two blood tests that should be used in the diagnosis and management of hypothyroidism.

The first is the TSH (thyroid-stimulating hormone) test. This is the most important and sensitive test for hypothyroidism. It measures how much of the thyroid hormone thyroxine (T4) the thyroid gland is being asked to make. When TSH is high, you have hypothyroidism.

Second, since most of the T4 in the blood is attached to a protein called thyroxine-binding globulin, testing for free T4 is an additional test. The free T4 and the free T4 index (also called the free thyroxine index) are both simple blood tests that measure how much unattached T4 is in the blood and available to get into cells.

According to a Dr. Mary Samuels (Oregon Health and Sciences University), "Most thyroidologists no longer use the FTI [Free Thyroxine Index] except in unusual cases (non-thyroidal illness, for one example [...]). The one other common scenario where a total T4 may be preferred to [a free T4 test] is during pregnancy [...], but this is controversial. Outside of these examples, FTI is less and less frequently ordered."

So in answer to your question, most endocrinologists will use a combination and will vary the combination based on the individual's circumstances (such as pregnancy).

You can learn more about hypothyroidism and diagnosing it in this article:

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Thank you for confirming that TSH is the basic test to show if hypo or hyper is present. My doubt, instilled by rebellious comments on the internet, is that it may not be the best guide to the dose of thyroxine the patient needs. I weave across the carpark to the doctor's ofice in cloudy dizziness. He glances at my TSH, sees that it is within the normal range,slaps me on the back and says, come back in three months. I've had normal TSH and T3,· T4 for five months. My symptoms are in some ways variable but they are still there. The latest I pick up on the net about this is that it can take from six months to a year to settle down???? I'd be grateful for your comment on this.

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Over the years I've had all the tests and have determined that it depends on the doctor as to how they are read. I had one doctor who would adjust my meds if any of these tests were out of the "norm" - compared to what he thought my norm should be. My current doctors accept part of them (Free T3 and T4) being slightly out of the norm as OK since the TSH is within the norm. My endocrinologist told me as long as I was between .5 and 2 - I was good -- who knows they all seem to read these tests differently.

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Have you been tested for other health issues? There are a great many things that have similar symptoms as hypothyroidism --- you should talk to your doctor again. My thyroid symptoms usually level out within the first month after a med change --- when they persist after 3 months I'm back in the doctor office -- so far they have found hypertension, Obstructive sleep apnea, and now hyperglycemic. And yes I think most of these tie back into the thyroid issue & it being out of kelter for close to 2 years.

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you need to be very careful when you deal with blood, if you don't complete the necessary tests then the patients are in great trouble, its always better to take services from cord blood banks centers who have experience in blood transfers

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I was diagnosed with hypothyroidism more than 10 years ago. The endocrinologist that I saw at that time saw me in 3 month increments until my tests were in the normal range AND until I FELT normal. He said that "what is normal for most people may not be normal for you as an individual" and he thought that my levels should be lower for me to feel "normal". I can tell by the way I feel when my thyroid is not "normal" for me. My thyroid has gradually gotten worse over the years, and my medication has had to be increased accordingly. I have been seeing a different doctor for the past 2 or 3 years, and I have to really argue with her to get her to increase my medication when I know that my levels are too high for my personal health. I got on this site and found that the recommendation is "find a doctor that makes you FEEL better, not just makes your labs better", and I'm going to follow that advice because I know I should feel better and have felt better than I do right now. This site also states that what works for 1 person doesn't necessarily work for another. Keep working on it until you feel better.

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