Is Your “Normal” Thyroid Test Really Telling The Full Story?

When people have weight issues, notice a decrease in energy or are dealing with brain fog, a common thought is usually that their thyroid may not be functioning well. So, they go to their doctor, who will usually run a test for thyroid stimulating hormone (TSH). TSH is the hormone produced by your pituitary gland to control the function of your thyroid gland. A high TSH means your pituitary senses that your thyroid is underactive. If it is, and not producing enough thyroid hormone (primarily T4), then it may be a reason why someone would be experiencing those symptoms.

The current normal range of TSH levels in adults is between 0.4 to 4.0 mIU/L (milli-international units per liter). Within that range your doctor would classify you as “normal” and likely rule out the thyroid as your problem. However, if that were the only test run, it may not give a true picture of the overall state of your thyroid. And even that value in the normal range may not mean your thyroid function is optimal.

Lab test ranges have high and low values, above and below which are usually the states where sickness, illness or disease conditions are present or more likely. But there is always the debate of whether someone is truly healthy if they are at the top or bottom of the normal ranges (meaning, getting close to abnormal). Such is the case with TSH. 

The National Health and Nutrition Examination Survey (NHANES III) demonstrated that the mean TSH in apparently normal, healthy participants is 1.4 uIU/mL. Based upon those results, The National Academy for Clinical Biochemistry has recommended since 2002 that a serum TSH level between 0.5-2.0 uIU/mL be considered the optimal therapeutic target for replacement treatment of hypothyroidism. This recommendation is supported by several studies showing that any TSH above 2.5 is associated with metabolic syndrome, insulin resistance, elevated fasting triglycerides, elevated blood pressure, and higher body mass index.

Where do all of those issues lead to? Just diabetes, hypertension and obesity, that’s all. Remember, thyroid controls metabolism throughout the body, and if it isn’t producing enough T4 hormone, everything tends to slow down. That includes production of other hormones, blood sugar management, body temperature, metabolism and the ability to burn fat, cell turnover, and virtually everything else. So, is it really good enough to have your thyroid function “just getting by”, or would you prefer it to be performing optimally?

In order to assess that, you first need to have a better look at your overall thyroid function. That means running a full thyroid panel that also includes total T4 and T3, free T4 and T3 and thyroid peroxidase (TPOAb) and Thyroglobulin Antibodies (TgAb), the last 2 being to rule out an autoimmune condition called Hashimoto’s, which has become the #1 reason for hypothyroidism in women in the United States. Only then can one get a full understanding of what is truly at the root cause of an underactive thyroid. From there, the correct treatment plan can be given to not only help improve health, but to keep the thyroid and body functioning optimally, not just merely “in the normal range”.