Issues with your thyroid can cause both daytime sleepiness and fatigue which aren't exactly the same complaint and can be difficult to separate.
At the very end, I put down some of the symptoms associated with too much and too little thyroid activity.
I see a lot of people with established thyroid issues, and a lot of people with undiscovered thyroid issues as well.
You can feel your thyroid yourself. It's a soft fleshy mass just below your hard, cartilaginous Adam's apple. It should not be lumpy.
As a non-car person, I still think a good and oversimplified analogy for the thyroid's role in the human body is the idle control motor on your car. When you start your car and it hums while just sitting there in Park, most of us don't notice the background idling of our car.... BUT we definitely notice it when something is amiss and it revs too fast making us think our engine is going to explode (and damage will be caused if left uncorrected), or our car keeps turning off on its own if it idles too slow. The thyroid helps maintain the body's background idle rate.
So that's the basics, but you should know the basic system setup here because it's important for you to know WHY certain things could be checked:
1. Your brain releases thyrotropin-releasing hormone (TRH for short) from the pituitary gland.
2. TRH travels down to the thyroid to make it rev your body up or slow it down.
3. The thyroid gland in response, releases T4 (also called thyroxine)
4. T4 travels into the nooks and crannies of the body to be converted into Free T3 (active) and the inert Reverse T3
5. Self-editing: Now, this isn't a dumb system. It works just like a factory if working properly. If you supply part of your factory with too much raw product, it will tell you to hold off. If you send not enough much raw product, then it yells at you to send more. That is where Thyroid Stimulating Hormone (TSH) comes into play. If your thyroid feels it needs to put out more T4 so more T3 can be working in the body, it tells your brain to send it more TRH to stimulate it (It can't stimulate itself). If the thyroid is working too hard for some reason, it will send out less TSH to the brain so the brain will stop stimulating it with TRH.
So again, TSH from the thyroid itself doesn't actually do anything in the human body... except act as a messenger to the brain to tell the brain if it (the thyroid) is working enough or not. It's like a self-reporting hormone always giving updates to the brain on well its own factory is doing.
SO.... some examples:
1. IF you hurt your pituitary, which, again, makes TRH, in a car accident, then the whole system gets shut down, because the thyroid can't get stimulated and it slows the whole body down. So TRH will be low because it's released by the pituitary. TSH from the thyroid (in the neck and uninjured) will be high because it doesn't know you were in an accident and is "yelling" at the brain to stimulate it. And of course T4/T3 will be low because the thyroid isn't stimulated.
2. If your thyroid is accidentally attacked by your own body, then it can't make T4/T3 which slows you down. But it also won't make TSH either to get the brain to kick it into gear.... so TSH and T4/T3 will be low, and TRH will often be low too (there are exceptions to this rule about TRH however).
3. If you have a thyroid tumor, it may produce too much TSH or too much T4 which will likely make your TRH low (the brain is trying to tell the thyroid to slow down, not knowing there is an additional cancerous factory) and your metabolism is running too fast.
But the truth is that you don't always have to have terrible diseases or accidents to have this system of TRH--TSH--T4/T3 become imbalanced. AND TSH is NOT always a reliable marker. But it is the most-often checked aspect of this system and can be misleading. TSH is most helpful when there is an obvious derangement, but is not always helpful for the more subtle, shade-of-grey derangements.
So what do I check?
I always check where the rubber meets the road, Free T3.
Now, Free T4 (thyroxine) is also active, just not as powerfully as Free T3, so I will check that too if I think it might be a subtle concern or if the thyroid is lumpy, mushy, too big, etc.... on palpation by exam.
I might check a TSH if the referring doctor has not already.
I rarely check the TRH, but as a neurologist who sees more head injury and other intracranial pathologies, I find myself checking it more than one would expect.
I also may check for two common antibodies: Anti-TPO (anti-thyroidal peroxidase antibodies) and Anti-TG (anti-thyroglobulin antibodies). They can be associated with immune disease in which one's body is accidentally attacking the thyroid gland itself causing it to rev the engine too much or not enough, and may not be obvious by the other tests.
Sometimes, T4 isn't converted appropriately into the more active T3 which can happen with stress/adrenal disease, chronic illnesses of various sorts, insulin resistance, heavy metal exposure, nutritional or enzyme deficiencies... and I will test for those concerns accordingly, although by then, I'm usually passing this to the tailored mind of the endocrinologist.
What can you do to replace a thyroid deficiency (besides find the cause of course)?
Synthroid (levothyroxine) contains only T4, which may very well be enough.
Armour Thyroid contains T3 which is the active form.
Deciding between these two and why is between you and your PCP.
Alternative medicines CANNOT replace your thyroid. Some supplements can help support a malfunctioning system... but ONLY if the exact source of breakdown is understood. For instance, I just saw a man who was on "lyophilized glands from animals," a thyroid natural supplement. While an excellent addition in some individuals, it wasn't treating this man's symptoms, and he was on the edge of having permanent heart damage despite his excellent intentions. Be careful!
If in doubt, be sure to bring it up with your Primary Care Doctor.
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