So, you have a thyroid test coming up. Do you need to fast for it? Let's talk about how different types of thyroid tests work, the purpose of fasting before a blood test, and what your thyroid hormone levels might indicate.
Most of the time, no, fasting will not be necessary before undergoing a thyroid test. However, one exception might be if your healthcare provider suspects you have subclinical hypothyroidism. In this case, they may recommend that you avoid consuming anything but water for several hours before your thyroid test.
The reason for this is that research tells us that the timing of a TSH test (thyroid stimulating hormone) can impact the results. More specifically, your level of thyroid stimulating hormone could drop significantly after you've eaten. This would, then, affect thyroid test results and thus, potentially the diagnosis and treatment that your healthcare provider recommends to balance out your thyroid levels.
If you're unsure whether or not you should fast before a thyroid test, ask your healthcare provider or the lab where you'll be getting the blood test done.
Thyroid scans are different from thyroid blood tests, but it's worth touching on them briefly.
In a thyroid scan (formally called thyroid scintigraphy), you swallow a capsule or liquid containing iodine-123 — a radiopharmaceutical, also called contrast material. With the radioactive iodine helping to "light up" your insides, a camera can then be used to take pictures of the thyroid. (And yes, the radioactive iodine is safe and generally well-tolerated.)
This diagnostic nuclear medicine test allows the physician to examine the size, shape, position, and function of the thyroid gland.
Thyroid tests, on the other hand, focus on measuring thyroid stimulating hormone (TSH), free T4, and other hormones.
When a thyroid scan requires contrast, the physician may require the patient to fast for a few hours before the scan.
As you now know, sometimes, eating or drinking (aside from water) can alter your test results — but not always.
There are certain types of blood components, like cells and platelets, that aren't impacted by what you consume and thus don't have any bearing on your blood test results.
However, if you're undergoing blood tests for anything measuring triglycerides (fat) or glucose (sugar), then these test results can return higher than normal levels if you got the test after eating.
In this case, fasting before blood tests gives healthcare providers a more accurate picture of your overall health.
Your thyroid gland — a butterfly-shaped gland — has a big job to do in producing hormones that your body needs to function optimally. Furthermore, it works with the other parts of the endocrine system — like the pituitary gland — to keep your hormones in check.
The thyroid produces two main hormones: thyroxine (T4) and tri-iodothyronine (T3).
Note: If you see "free T4" on your thyroid test results, it's referring to T4 that is not attached to any protein in the blood.
Where does thyroid stimulating hormone come into play?
Well, that one is produced by the pituitary gland. The pituitary gland makes TSH to signal to the thyroid to make more T3 and T4.
Additionally, you might see TSH reflex to free T4 on your thyroid blood test.
All of these thyroid hormone levels give a better idea of what your overall thyroid function looks like. They all need to fall within the ranges considered normal so that you can feel your best.
If you're wondering what your thyroid gland is up to, eNational Testing can provide insight with our thyroid panel. This checks your TSH, T3, and free T4. Test results are usually available within one business day.
Order your thyroid panel online today.
You might notice that your thyroid test results show where your thyroid hormones are within pre-determined reference ranges.
These ranges are generally accepted as the "sweet spots."
So, what happens if you're outside of these ranges?
Well, if your thyroid stimulating hormone is low, this means there's too much of it, and it's indicative of an overactive thyroid (hyperthyroidism). High TSH levels mean that the pituitary gland isn't producing enough thyroid hormone, and you have an underactive thyroid (hypothyroidism).
Learn about hypothyroidism vs hyperthyroidism.
High T3 levels could indicate hyperthyroidism and low T3 is the opposite. And the same can be said for free T4.
So, depending on how high or low your thyroid hormone levels are, your provider can better tell you if you have an underactive thyroid, overactive thyroid, or optimal thyroid function.
If you do have some sort of thyroid dysfunction, then your provider might recommend yearly (or even more frequent) blood tests to monitor your health and ensure your thyroid hormone levels are where they should be.
If they're not, lifestyle changes and certain medications can help get your thyroid hormones back into the ideal ranges.
Your thyroid hormones aren't only important for this specific gland or even just for your endocrine system as a whole. If your thyroid function isn't what it needs to be, it could severely impact your quality of life.
For instance, symptoms of an overactive thyroid include:
An underactive thyroid gland can trigger symptoms like:
This is why it's so vital to monitor your TSH levels, T3, and free T4 with regular thyroid tests.
Aside from thyroid medication (if it becomes necessary), what else can you do to ensure that your thyroid gland has the greatest chance for success?
Keep these simple tips in mind:
You might be doing these things already since they're important for your general health outside of your thyroid function. If so, then you're already on the right track!
eNational makes the process of getting blood tests easier than ever.
We have more than 2,000 locations across the United States, so getting thyroid blood tests is faster and more convenient, no matter where you live. You don't even need to see your doctor first.
Simply find a testing center near you and order your thyroid blood test online in just a few clicks!
If your results are outside the normal ranges and indicate that you might have some sort of thyroid condition, then you'll have the opportunity to speak with a health care professional about how to improve your thyroid health.
If you're ready to take the next step, order your panel today to learn more about the current health of your thyroid gland.