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 thyroid 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% of the 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 thyroid 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.

With this thyroid 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 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.

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 thyroid 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.

5. THYROID RESISTANCE

In this thyroid 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.

The five thyroid 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 thyroid 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 mentioned, 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.

About the Author

Chris Kresser graduated from the Acupuncture and Integrative Medicine College in Berkeley on April 2010. Passed the California Acupuncture Licensing Exam in August of 2010, and has a private practice in Berkeley, CA. He is one of the best resources around for simple and clear evaluation of the latest scientific research out there. Chris is a licensed acupuncturist and functional medicine practitioner and specializes in treating metabolic problems, chronic fatigue, thyroid dysfunction, and digestive problems. He also consults with patients throughout the U.S. via telephone and Skype. Follow Chris at his website, ChrisKresser.com and if you’d like his help, check out his different programs. Follow him on Facebook and Twitter.

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