by Chris Kresser

This article is part of a special report on Thyroid Disorders. 

In medicine, the key to choosing the best treatment is an accurate diagnosis. If the diagnosis isn’t correct, the treatment will be ineffective – or even cause harm.

Unfortunately misdiagnosis is common in the management of hypothyroidism. If you go to a doctor with hypothyroid symptoms, you’ll simply be given replacement hormones without any further inquiry into the cause of your condition.

Even worse, if you have hypothyroid symptoms but your lab tests are normal, you’ll be told you’re “fine”. If you insist you’re not, you might be sent home with an antidepressant, but no further clue about the cause of your symptoms.

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. It’s incorrect and even negligent to assume that all cases of hypothyroidism share the same cause and require the same treatment. Yet that’s exactly what the standard of care for hypothyroidism delivers.

In this article I’ll present five patterns of thyroid dysfunction that won’t 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 if you go to your conventional doctor, you’ll be told there’s nothing wrong with your thyroid.

A standard thyroid panel usually includes TSH and T4 only. 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 normalrange? 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)

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. 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).

  1. 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% 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. High cortisol also suppresses the conversion of T4 to T3.

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.

  1. 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.

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.

  1. 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. 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.

  1. 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 resistance is usually caused by chronic stress and high cortisol levels. It can also be caused by high homocysteine and genetic factors.

Conclusion

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. The reason the conventional approach fails is that it skips this step and gives the same treatment to everyone, regardless of the cause of their problem.

The good news is that, once the correct diagnosis is made, patients respond very well to treatment.

 

Source:chriskresser.com

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