Guest Blog post by Paloma Health
Thyroid blood tests are necessary to diagnose and treat thyroid diseases. However, to fully understand your thyroid function, you will need lab work that looks at several markers, including TSH, free T3, free T4, and TPO antibodies. Knowing how to interpret your results can be slightly confusing, especially if you do not have a lot of guidance. What is more, it can be extremely troubling if your lab values do not match your symptoms and your doctor says you are good to go. Ahead, a rundown on how to read a full thyroid panel and be your own advocate when it comes to your thyroid care.
What’s included in a complete thyroid panel?
There are three leading labs you should check for if you are looking to rule out thyroid conditions of hyperactivity or hypoactivity. These labs look directly at the hormones involved in thyroid hormone production and concentration in the bloodstream.
Thyroid-stimulating hormone is the most common test doctors will order to assess thyroid function. This hormone is released by the anterior pituitary gland in your brain and tells the thyroid how much thyroid hormone to make and release. When TSH increases, the pituitary is “stimulating” the thyroid to produce more hormone because it detects thyroid hormone levels are too low in the bloodstream. If TSH levels are low, it means that the thyroid should decrease the amount it is producing. TSH is the most common test doctors will order when assessing a patient’s thyroid function. However, while it can tell you a lot about thyroid function, it does not tell the whole picture.
Thyroxine (T4) is one of the forms of hormone the thyroid makes and releases into the bloodstream. Most of the hormone produced by the thyroid is T4. However, T4 is a storage form of thyroid hormone, so it is relatively inactive. About 80% of the thyroid hormone in the body is T4. A free T4 test measures the amount of T4 free of binding proteins and ready for uptake within cells.
Triiodothyronine is the active form of thyroid hormone. It becomes active once T4 converts to T3 in the liver and other body tissues. About 20% of thyroid hormone in the body is T3, and it is responsible for regulating cellular metabolism.
Interpreting your complete thyroid panel
When you get your thyroid function test back, you should hopefully have results for each of the above tests. Normal lab values may vary based on the laboratory that processes your results, but most labs will follow a similar reference range. Here are typical lab values are for each thyroid marker listed above:
- TSH is considered normal between 0.5 – 5.0 mIU/L
- Free T4 is considered normal between 0.9 – 2.3ng/dL
- Free T3 is considered normal between 130 – 450 pg/dL
If TSH is between 4.7 – 10 mU/L, you may have subclinical hypothyroidism. Again, TSH is elevated because your thyroid is not making enough thyroid hormone. Test results above 10mU/L are considered overt hypothyroidism, which requires medication. Some doctors may recommend treating people in the subclinical range, especially if they are symptomatic. Now, TSH does not provide the complete picture, which is why T4 and T3 can be so helpful. The following is generally how your doctor interprets these labs results:
- A normal TSH and normal T4 and T3 indicated a normal functioning thyroid.
- Low TSH and high T4 and T3 usually mean hyperthyroidism.
- High TSH and low T4 (and sometimes T3) suggest primary hypothyroidism caused by thyroid disease.
- Low TSH and low T4 suggest secondary hypothyroidism, which is usually due to a condition of the pituitary or hypothalamus.
What about reverse T3?
Sometimes, reverse T3 (rT3) is a valuable test to measure, especially if a patient is undergoing severe stress, such as trauma, surgery, or malnutrition. Reverse T3 is a byproduct of T4 metabolism and is the inactive form of T3. Thus, it is not as effective at carrying out the same metabolic activities as free T3. Sometimes, rT3 becomes elevated as an adaptive mechanism to help the body when you want to decrease thyroid hormone activity within cells.
What other tests help complete the picture?
The above values tell us valuable information about our thyroid function. However, skilled thyroid doctors may also add additional testing to understand better what is going on in the thyroid. Some of these tests look for autoimmune processes, whereas others look at problems with binding proteins or cancer. Some of these additional tests may include: TPO antibodies to help confirm Hashimoto’s disease, which is an autoimmune disease that causes hypothyroidism. Tg antibodies also confirm Hashimoto’s disease, as well as Graves’ disease and postpartum thyroiditis. Tg tests to help detect cancer reoccurrence and may predict long-term outcomes of cancer treatment. TGB test to measure the level of protein that helps move thyroid hormone throughout the bloodstream.
How to be your own advocate with testing
Although lab tests are extremely valuable in giving you and your doctor a picture of what is going on in your thyroid gland, your health is more than just numbers. But, time and time again, we hear of patients being dismissed by their doctor once they get the all-clear on their thyroid bloodwork. Or, their doctor only prefers to perform one test, such as TSH, and does not investigate things further, even though you are struggling with symptoms. At least 20 million Americans have thyroid disease, and every person has a unique experience in how they feel their symptoms and how they respond to medication. Therefore, thyroid care does not fit a one-size-fits-all approach, and each person requires individualized management. The road to health and wellness can be long and a bit rocky, so make sure you have an excellent thyroid care team backing you. Paloma Health makes it easy to get a complete thyroid panel with an at-home thyroid test kit and trusted thyroid doctors to follow up virtually with you to help you on your way to optimal thyroid health.
About Paloma Health
Paloma Health is the first online medical practice focused exclusively on testing and treating hypothyroidism The company offers access to at-home thyroid tests, virtual consultations with thyroid doctors and nutritionists, and prescription and supplement management for an integrated health experience.