Making Sense of Thyroid Lab Results

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Thyroid disorders are prevalent in our culture, and are unfortunately often poorly managed within the conventional system.   I find myself explaining thyroid function and assessment on a daily basis.  It is a complex topic and requires a significant amount of time to cover thoroughly during a consultation. 

I am hopeful this article will serve as a reference for those of you working with an imbalanced thyroid.

While symptoms are more important to me than lab values, in the case of thyroid disorders the following tests make my job easier.  And, thorough testing usually means that you begin to feel better faster because we are able to support you as specifically and efficiently as possible.

Thyroid testing:

TSH (Thyroid stimulating hormone) - is the hormone released by your pituitary gland to stimulate your thyroid to produce thyroid hormone.

Within the conventional system, this is the current test used in diagnosis of a thyroid disorder.  The “official” normal range for adults is quite broad – 0.5-5.0.  This range remains despite the fact that the AACE (American Association of Clinical Endocrinologists) announced in 2002 that the range of TSH should be narrowed to 0.3-3.0.   The goal of this recommendation was to enable physicians to diagnose and treat thyroid disease early, before it can lead to more serious conditions such as hypercholesterolemia, heart disease, osteoporosis, infertility and depression.   Unfortunately, every week I have people coming into my office with symptoms of hypothyroidism (fatigue, weight gain, difficult focus, hair loss, depression…) in whom a thyroid disorder has been ruled out because TSH was within the normal range.

I find that most people feel best when their TSH is between 0.5-1.8

Free T4 (Thyroxine) - is the main thyroid hormone produced by the thyroid gland. I refer to it as a pre-hormone because it is only about 10% metabolically active even though it represents roughly 90% of circulating thyroid hormone. The "free" part means we are measuring the quantity of hormone not bound to other proteins in the blood.  When T4 levels are adequate, your pituitary gland receives the message that enough TSH is being produced.   This means that TSH can be normal, even when your body is not converting T4 to T3.

Free T3 (Triiodothyronine) - represents our body's most active thyroid hormone. The T4 in circulation is converted within our liver and kidney into T3.  T3 stimulates cellular metabolism. T3 represents only about 10% of circulating thyroid hormone but is about 90% active. Again, we want to make sure we measure the free levels of this hormone to properly assess what is available to our cells.

Thyroid antibodies (TPO, ATA, TSI) - These antibodies play a critical role in many thyroid conditions. Eighty percent of women that have hypothyroidism have it due to an autoimmune condition referred to as Hashimoto's Disease. The TPO (thyroid peroxidase antibodies) and the ATA (anti-thyroglobulin antibodies) are two critical markers present when an autoimmune process is at play.  The TSI antibody is related to an autoimmune hyperthyroid state called Graves' disease.

Within the conventional system these tests are often overlooked, even in people with a longstanding thyroid condition.  From a conventional perspective, the treatment of an autoimmune thyroid condition is essentially the same as a non-autoimmune thyroid condition.  Naturopathically, we will work to resolve the autoimmune condition, so, knowing whether it is underlying a thyroid imbalance is very important.

Reverse T3 - If cortisol levels are high, your body can convert the T4 hormone into reverse T3 instead of regular T3. The reverse T3 will bind to the T3 receptor site but will not activate it. In the process, reverse T3 blocks these receptor sites from regular T3 and the net effect is your body having less T3 stimulation and reduced metabolism. This is an attempt by our body to preserve energy levels in times of stress.  If this level is high, it can indicate that an adrenal imbalance is underlying your thyroid disorder.

Thyroid issues rarely exist in isolation.  Underlying conditions that may be related include: imbalances within the adrenal or reproductive system, food sensitivities (often gluten enteropathy), and vitamin/ mineral deficiencies.  Further testing may be recommended depending on other relevant symptoms.