Unfortunately a misdiagnosis can happen in the management of hypothyroidism and other thyroid disorders. If you go to a doctor with hypothyroid symptoms, you may be given replacement hormones without first determining what’s causing your thyroid issues.
Or, if you have hypothyroid symptoms but your lab tests are normal, your doctor may not realize you’re experiencing thyroid issues in the first place. You may even receive treatment or medication to deal with the symptoms you’re experiencing—like an antidepressant to address depressive symptoms—but you won’t receive anything that will help your thyroid disorder.
The problem with this approach is that thyroid physiology is complex.
The production, conversion, and uptake of thyroid hormone in the body involves several steps. A malfunction in any of these steps can cause hypothyroid symptoms, but may not show up on standard lab tests.
All cases of hypothyroidism do not share the same cause—and, as you might guess, they require different treatments.
In this article, I’ll present five patterns of thyroid dysfunction that may not show up on standard lab tests. If you have one of these patterns, your thyroid isn’t functioning properly and you will have symptoms. But depending on the tests your doctor runs, you may not get a diagnosis of hypothyroidism; and, if that’s the case, you won’t receive the treatment you need.
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A standard thyroid panel usually includes TSH and T4 only (while some panels will also look at free T3, free T4, and check for thyroid antibodies). The ranges for these markers vary from lab to lab, which is one of two main problems with standard lab ranges. The other problem is that lab ranges are not based on research that tells us what a healthy range might be, but on a bell curve of values obtained from people who come to the labs for testing.
Now, follow me on this. Who goes to labs to get tested? Sick people. If a lab creates its “normal” range based on test results from sick people, is that really a normal range? Does that tell us anything about what the range should be for health? (For more on the problems with standard lab ranges, watch this great presentation by Dr. Bryan Walsh)
Are you experiencing hypothyroidism symptoms even though your lab work is normal? You may still have hypothyroidism, though it may not show up on standard labs. Check out this article for more. #functionalmedicine #chriskresser
The Five Thyroid Patterns
1. Hypothyroidism Caused by Pituitary Dysfunction
This pattern is caused by elevated cortisol, which is in turn caused by active infection, blood sugar imbalances, chronic stress, pregnancy, hypoglycemia, or insulin resistance. (1) These stressors fatigue the pituitary gland at the base of the brain so that it can no longer signal the thyroid to release enough thyroid hormone. There may be nothing wrong with the thyroid gland itself. The pituitary isn’t sending it the right messages.
With this pattern, you’ll have hypothyroid symptoms and a TSH below the functional range (1.8 – 3.0) but within the standard range (0.5 – 5.0). The T4 will be low in the functional range (and possibly the lab range too).
2. Under-Conversion of T4 to T3
T4 is the inactive form of thyroid hormone. It must be converted to T3 before the body can use it. More than 90 percent of thyroid hormone produced is T4.
This common pattern is caused by inflammation and elevated cortisol levels. T4 to T3 conversion happens in cell membranes. Inflammatory cytokines damage cell membranes and impair the body’s ability to convert T4 to T3. (2) High cortisol also suppresses the conversion of T4 to T3. (3)
With this pattern you’ll have hypothyroid symptoms, but your TSH and T4 will be normal. If you have your T3 tested, which it rarely is in conventional settings, it will be low.
3. Hypothyroidism Caused by Elevated TBG
Thyroid binding globulin (TBG) is the protein that transports thyroid hormone through the blood. When thyroid hormone is bound to TBG, it is inactive and unavailable to the tissues. When TBG levels are high, levels of unbound (free) thyroid hormone will be low, leading to hypothyroid symptoms. (4)
With this pattern, TSH and T4 will be normal. If tested, T3 will be low, and T3 uptake and TBG will be high.
Elevated TBG is caused by high estrogen levels, which are often often associated with birth control pills or estrogen replacement (i.e. Premarin or estrogen creams). To treat this pattern, excess estrogen must be cleared from the body.
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4. Hypothyroidism Caused by Decreased TBG
This is the mirror image of the pattern above. When TBG levels are low, levels of free thyroid hormone will be high. You might think this would cause hyperthyroid symptoms. But too much free thyroid hormone in the bloodstream causes the cells to develop resistance to it. So, even though there’s more than enough thyroid hormone, the cells can’t use it and you’ll have hypothyroid—not hyperthyroid—symptoms.
With this pattern, TSH and T4 will be normal. If tested, T3 will be high, and T3 uptake and TBG will be low.
Decreased TBG is caused by high testosterone levels. (5) In women, it is commonly associated with PCOS and insulin resistance. Reversing insulin resistance and restoring blood sugar balance is the key to treating this pattern.
5. Thyroid Resistance
In this pattern, both the thyroid and pituitary glands are functioning normally, but the hormones aren’t getting into the cells where they’re needed. This causes hypothyroid symptoms.
Note that all lab test markers will be normal in this pattern, because we don’t have a way to test the function of cellular receptors directly.
Thyroid Treatment Depends on the Right Diagnosis
The five patterns above are only a partial list. Several others also cause hypothyroid symptoms and don’t show up on standard lab tests. If you have hypothyroid symptoms, but your lab tests are normal, it’s likely you have one of them.
Not only do these patterns fail to show up on standard lab work, they don’t respond well to conventional thyroid hormone replacement. If your body can’t convert T4 to T3, or you have too much thyroid binding protein, or your cells are resistant, it doesn’t matter how much T4 you take; you won’t be able to use it.
Unfortunately, if you have one of these patterns and tell your doctor your medication isn’t working, all too often the doctor’s response is to simply increase the dose. When that doesn’t work, the doctor increases it yet again.
As I said at the beginning of this article, the key to a successful treatment is an accurate diagnosis. Without understanding precisely what’s causing the problem, you may end up with a treatment that isn’t well-suited to your specific situation.
The good news is that, once the correct diagnosis is made, patients respond very well to treatment.
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