Hypothyroidism: Beyond Testing the TSH

Dr. Preet Khangura, ND

Hypothyroidism is an extremely common, and unfortunately, under diagnosed and mismanaged condition. Conventional thinking describes hypothyroidism as a condition in which the thyroid gland does not produce a sufficient amount of thyroid hormone. This can be indicated on a blood test when thyroid-stimulating hormone (TSH) is abnormally elevated.   If TSH is elevated, it means that the brain realizes that the thyroid gland is not producing enough thyroid hormone, and therefore, needs to release high levels of TSH to kick-start the thyroid gland. However, this traditional way to assess for hypothyroidism only occurs in about 1 out of 10 patients with hypothyroid signs and symptoms. To make things worse, conventional treatment for hypothyroidism, namely synthetic T4 hormone (such as Synthroid), usually makes hypothyroid symptoms worse over time – even though the lab markers such as TSH improve.

So why are there so many people suffering from hypothyroidism and either not being diagnosed, or being diagnosed, but do not experience benefits of treatment? The answer is two fold. TSH is not an accurate measure of thyroid system function, and secondly, use of T4 medication can make their thyroid system work less efficiently – therefore, making their hypothyroidism worse. Before going forward, let’s look at just a partial list of hypothyroid signs and symptoms:

Fatigue

Cold hands and feet

Depression

Insomnia

Elevated cholesterol

Slow wound healing

Easy weight gain

Water retention

Anxiety

Headaches

Asthma

Easy bruising

Cold or heat intolerance

Hair loss

Constipation

Dry skin/dry hair

Hives

Irregular menstrual cycle/PMS

The thyroid gland primarily produces a thyroid hormone called T4 and sends it out into circulation. T4 is more of a storage form of thyroid hormone, and not a highly bioactive form. T4 is then converted into the active thyroid hormone named T3 via the liver, kidneys, and skeletal muscle. T3 is the thyroid hormone that actually enters our cells and promotes DNA transcription, which then provides us with all of our thyroid hormone benefits. Because the level of T4 in our blood is what primarily regulates TSH, testing for TSH can lead to false negatives of hypothyroidism if the T4 is not being converted into enough T3. This is why many patients with hypothyroid symptoms have normal TSH levels, and therefore, do not get the proper diagnosis of hypothyroidism.

T4 converting to T3 is regulated by an enzyme that requires specific nutrients to be at sufficient levels. Therefore, if these nutrients are in deficiency levels, T4 may not convert into sufficient levels of T3, and hypothyroid symptoms can arise. Another important factor to consider is the fact that T4 can also be converted into something called Reverse T3 (RT3). This is a form of thyroid hormone that is completely inactive and provides no thyroid hormone benefit. If T4 is over converting to RT3, the levels of T3 will fall, and hypothyroidism can occur. Some causes of RT3 conversion being up regulated are excess cortisol production via stress, chronic inflammation, calorie restriction, and certain medication use. One other primary cause of increased RT3 is actually the most conventional treatment for hypothyroidism – using T4 medication. As T4 levels increase in the blood, the body responds by increasing RT3 levels. This is why numerous patients feel even worse after initiating T4 medication use for their hypothyroidism.

Regardless if the enzyme that converts T4 to T3 is not functioning well, or if T4 is over converting to RT3, a person can be exhibiting hypothyroid signs and symptoms while their TSH is considered perfectly normal. So if TSH is not an accurate measure of thyroid function, how should one be assessed? This is done by a combination of body temperature measurements, RT3 blood tests, and signs and symptoms. And just as importantly, the treatment should only focus on increasing T3 levels and the efficiency of converting T4 to T3. If you suspect hypothyroidism or are being treated for hypothyroidism with T4 medication (such as Synthroid) and you do not feel any better, or even feel worse, do not hesitate to be evaluated by a physician who looks beyond TSH.

References:

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