Comprehensive thyroid testing: getting the full picture
Your thyroid gland is a butterfly-shaped organ in your neck that produces the thyroid hormones T4 and T3. These hormones regulate your metabolism, which is the sum of all the chemical processes involved in using fuel to produce energy so that every cell can carry out whatever biological function it’s designed to. Fun fact: thyroid hormones are one of the only substances that every. single. cell. in our bodies has a receptor for (the other being vitamin D) - that tells you how important they are.
So because your thyroid hormones are essentially controlling how well every cell can perform its individual function, it’s not surprising to learn when they’re suboptimal there is a flow on impact to many physiological processes, which means lots of different symptoms that can spring up. The processes that take the biggest hit are the ones in our body that are the most energy hungry: our brain (mood, brain fog & fatigue), our gut (reduced digestive secretions & motility) and our cycles ladies (delayed periods, heavy bleeding & recurrent miscarriages). A common picture of reduced thyroid output would be someone who’s exhausted and flat all the time, has put on weight they can’t shift, is experiencing constipation and their period has gone haywire.
If you go to the GP with these symptoms they’ll likely want to do a blood test checking up on a few things, including your thyroid function. But when the GP checks up on your thyroid they are only going to look at something called TSH (thyroid stimulating hormone) – it’s the hormone that comes from your brain asking your thyroid gland to make thyroid hormones. There are a few reasons for this, but essentially Western medicine only recognises there is enough damage to the thyroid gland to warrant a diagnosis of hypothyroidism after that TSH hits a certain number.
Unfortunately, thyroid destruction can begin up to ten years prior to TSH entering this range, and the only way to tell if this is happening is to have a more comprehensive blood test. This includes:
- TSH (thyroid stimulating hormone). Somewhat confusingly, when this number is elevated, it indicates reduced thyroid output, because it responds to how much thyroid hormone is in your body. So if your thyroid is struggling to pump out enough hormones, the brain responds by increasing this to try to force the thyroid to produce more.
- Thyroid hormones (T4 and T3): T4 is what’s pumped out by the thyroid gland and is for the most part inactive. It gets converted to the active thyroid hormone T3 throughout your body, mainly in the liver. Looking at the level of these hormones in relation to each other and to TSH can help you figure out if the issue is with your thyroid (including whether you’re deficient in the nutrients needed to produce T4) or your body’s ability to convert the hormones to active forms.
- Thyroid antibodies (thyroglobulin and/or thyroid peroxidase): this is to determine if there’s an autoimmune element to your hypothyroidism i.e. Hashimoto’s (which there is 95% of the time in hypothyroidism). But to note, thyroglobulin antibodies can occur in a range of thyroid conditions, not just Hashimoto’s.
- Reverse T3: this is an inactive hormone that T4 gets converted to if something is getting in the way of it converting to active T3. This usually happens if you’re struggling with illness or chronic inflammation, because it’s the body’s way of trying to force you to slow down and rest. Technically we can get away without this one, because you can see if T4 is high and T3 is low, it’s likely because a portion of the T4 is being converted to RT3.
If you want the full thyroid panel, including antibodies, this is something you will likely have to pay for yourself, and it costs around $125 (without RT3).