Jan 2, 20213 min read

What are the best tests for thyroid function and why?

Jane was having difficulty maintaining her energy throughout the day. She attributed it to poor sleep and more stress with her work, but she was also experiencing changes in her hair, increased anxiety, and she was putting on weight.

She set up an appointment wit her family practitioner, who checked some basic lab work, including iron levels, electrolytes, and a TSH.

All came back normal (or within normal lab limits according to the laboratory reference ranges). Her practitioner advised to eat less, exercise more, and lower stress.

But none of this worked, and she continued to have symptoms for years, before a friend mentioned that Jane probably needed a more comprehensive evaluation. With the right testing, she was finally able to get the right treatment and improve her life.

Unfortunately, all too often this scenario occurs in mainstream medicine. Often, the labs that are ordered are dictated by medical algorithms, which then determine insurance coverage of a lab. Patients know something is not right, and the practitioner often feels helpless by the inability to “cure” the patient’s symptoms.

There are over 300 symptoms that correlate with thyroid dysfunction. A low-output thyroid (aka hypothyroidism) is the most common condition, but 5% of thyroid problems can come from an over-active thyroid (aka hyperthyroidism). If you suspect you may have a thyroid condition, or know someone who does, it all starts with the right tests – tests that look at thyroid FUNCTION:

TSH (Thyroid Stimulating Hormone): This hormone comes from an area of the brain known as the pituitary. It is not created by the thyroid (which is found at the base of the throat), but it does affect the hormones produced by the thyroid. Think of this as the “SOS” signal – there will be more signals if not enough thyroid hormones are being produced, and there will be no/few signals if there are enough thyroid hormones circulating in the body. The problem with this is that it mostly responds to levels of T4 (which aren’t the active thyroid hormones)
Free T4: The main hormone produced by the thyroid gland. This hormone has to be converted into free T3 to activate (i.e. exert effects on the body, such as regulate metabolism and energy).
Free T3: Some of this produced by the thyroid, but the majority of this comes from the conversion of free T4 into free T3. This conversion happens all over the body, but is particularly active in the liver and in the gut (which is why gut health and liver function is so important to maintaining optimal thyroid hormone levels!).
Thyroid peroxidase antibodies (TPO antibodies), aka the “soldiers” that mistakenly see parts of the thyroid gland as “foreign invaders”. These are created by the immune system, and can be detected in blood tests 10 or more years before other changes are seen in other blood tests. This is associated with a poor functioning thyroid, but can also be associated with a hyperactive thyroid gland.

Even if you have had your TSH checked, if this is over 2 years ago and you have symptoms of hypothyroidism, you owe it to yourself (and your loved ones) to dig a little deeper!

References:

Why we need to check antibodies in women with thyroid-associated symptoms: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3167665/

Thyroid dysfunction in the era of precision medicine: http://www.elsevier.es/en-revista-endocrinologia-nutricion-english-edition–412-articulo-thyroid-dysfunction-in-era-precision-S2173509316300745

Euthyroid sick syndrome overview: https://www.ncbi.nlm.nih.gov/pubmed/9086580

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