The enigma about Thyroid Tests
My daughter, 17 years old now, was recently send to the lab to get her thyroid tests done, as a part of her annual physical exam. Surprisingly, her TSH came out of the “normal” range. The paper said that her TSH was 0.32 µIU/mL (reference ranges for that age group 0.50- 4.30), which clearly indicates some kind of a hyperthyroid problem. But she did not have any symptoms at all, and if she did, I would be the first to notice them. Clearly, they got the wrong mother to tell that my daughter may have hyperthyroidism. I insisted this thyroid test to be repeated and since they never called me again, I assume that it came out normal this time. How did that happen?
Tests may lie, your symptoms don’t
One thing that I have learned through the years being thyroid patient advocate is that thyroid patients don’t lie, but their thyroid tests definitely may. Many people would report that they have normal test results (i.e their TSH, FT3 and FT4 are within the normal ranges), as per their doctors and lab results, but they still have persistent symptoms (regardless hypothyroidism or hyperthyroidism). It is very difficult to get a correct diagnosis of hypothyroidism or hyperthyroidism because the modern medicine chooses to view laboratory test results as the gold standard and as teh only indicator for diagnosing these disorders.
What does your thyroid hormones mean?
Many physicians use TSH results as the only indicator of thyroid disorder. However, TSH is not even a hormone, produced by the thyroid gland, it is a pituitary hormone. Other physicians use T4 is indicator, however, T4 is not the active hormone, it is the T3. As you probably already know, the thyroid gland is specialized in hormone secretion, particularly two hormones: thyroxin and triiodothyronine (respectively T4 and T3). The only difference between these two hormones is the number of iodine molecules that they contain (respectively 3 molecules and 4 molecules of iodine) but both are extremely significant for managing the body metabolism. The production of these two hormones is practically managed by the production of TSH (Thyroid Stimulating Hormone) produced in the pituitary gland and the Thyrotropin-releasing Hormone (TRH), which is released by the hypothalamus. Both organs (hypothalamus and pituitary gland) serve as check points to detect whether or not the organism is getting enough thyroid hormone. The thyroid gland is estimated to secret about 80% of the thyroxin (T4) and 20% of the triiodothyronine (T3). However, the larger quantity of T4 (thyroxin) doesn’t mean that it is the more important hormone. In fact, the active hormone is T3 and some of the thyroxin (T4), through complex chemical processes, is converted to T3.
How the “normal” laboratory ranges are defined?
The “normal” ranges are defined based on the test results of the previous 1000 patients. These 1000 patients are randomly chosen but guess what? These are people who are usually in their middle ages, as young people don’t get tested for thyroid problems regularly. This means that the laboratory will use 47.5% below the average and 47.5% above the average to determine the so called “normal” ranges or “the mean”. But it is obvious, that by using this particular method about 95 of the population should fall within this “normal” range. I highly doubt that this is true and I believe that these normal ranges are very subjective. Not to mention that the optimum thyroid level for one person may not be the same for somebody else. It’s very much like trying to buy a dress, let’s say size 10. You may usually wear size 10, but dresses differ depending on the material or the model (women know that). So that size ‘10” that you usually wear may not fit at all, regardless that the sale person may insist that the dress is perfect and there is something wrong with you or your thinking. Same with the thyroid tests…
Thyroid Tests Laboratories differ
If you get tested in different laboratories, you may get completely different results because of the method they use, already described above. A reference range is usually defined as the set of values 95 percent of the normal population falls within (that is, 95% prediction interval). But was that 95% of the population really healthy? Normal ranges will also differ from lab to lab depending on sample populations, testing procedures and equipment. Try different laboratories and see if you don’t believe me.
“Normal” ranges change over time
In 2002, the National Academy of Clinical Biochemistry (NACB) issued new guidelines for the diagnosis and treatment of thyroid disorders. To prove their guidelines, it was announced that after additional tests the TSH levels of the 95% of the healthy population actually fall within 0.4 and 2.5 µIU/mL. Almost immediately after that, in 2003, the American Association of Clinical Endocrinologists supported NACB, saying that for TSH “normal” levels should be considered the ranges between 0.3 to 3.0 µIU/mL. For more than 10 years later these ranges hasn’t changed. Which also means that if you went to a doctor in 2002 and your levels were let’s say 2.6, you won’t be considered hypothyroid, you will not be treated and you will be dismissed, regardless if you do have or do not symptoms.
Thyroid levels differ during the day
Thyroid levels may fluctuate during the day and they depend also on other medications you may be taking, supplements, hormones and even stress. However, many lab technicians fail to advise their patients to come early in the morning, before any breakfast and food. It is no requirement, as I have found. This alone can throw you in or out of the normal ranges with a blink of an eye. But then your medication may be increased, or reduced, based on this thyroid test results alone.
Your basal temperature matters or how to get more correct results
Measure your basal temperature: Normally, the average temperature of an adult with a healthy thyroid and a healthy metabolism is 98.6 degrees Fahrenheit or 37.0 degrees Celsius, and that occurs around mid-afternoon or 3 pm. But have in mind that if you measure your temperature before getting out of bed in the morning the basal temperature should be between 97.8 – 98.2 F or 36.6 to 36.8 degrees Celsius (using a normal thermometer under the arm for ten minutes). So, if you take your mid-afternoon temp and find it under this range, that may be an indication that you may have hypothyroidism and/or you are undertreated. If it is above this reference range, you may be hyperthyroid. One last thing: do not use a cell phone at least 30 minutes prior to taking your temperature, it will be affected. For a free temperature graph, check Dr. Rind website:
What should you do?
1. Try to schedule your thyroid tests early in the morning and try not to consume any food in the past 12 hours.
2. If your test results come “normal” but you are experiencing unexplained symptoms or you still have symptoms even though declared “normal” do not hesitate to ask for this thyroid panel to be repeated in a few days.
3. If still in doubt, chose another laboratory so you can compare the results (and your doctor as well).
4. Ask your doctor to interpret the result in the context of your overall medical condition and symptoms to determine if there is reason for concern.
If you have any experience with “strange” test results, or you still have symptoms, but “normal thyroid test results, share your experience, it may help other people as well.