Thyroid Stimulating Hormone (TSH) is a common lab test used to diagnose a Thyroid Disorder.
Its Optimal range should be 0.5-2.0 uU/ml.
It's been said that in the case of hypothyroidism, Your TSH increases and in the case of hyperthyroidism, Your TSH decreases.
Nevertheless, sometimes we deal with a patient who has optimal TSH and yet still experiences symptoms of hypothyroidism. The truth is that TSH is the best way to diagnose a pituitary problem, not a thyroid problem.
Why is it so?
Because of the nature of this test.
This test is used to tell us that pituitary gland is "saying" the thyroid gland to release more thyroid hormones!
It doesn't though tell us how much active thyroid hormones Your cells are receiving.
What's more, if You suffer from Hashimoto’s, Your lab results will most probably fluctuate between hypo and hyperthyroidism.
It happens because at the beginning of the disorder, the thyroid cells become destroyed, the hormones that normally have been stored, are now released into Your circulation.
It leads to Thyrotoxicosis, which is an excess of thyroid hormones in the body.
Thus, You're having symptoms of hyperthyroidism and Your lab tests look differently.
Then , at some points, cells become depleted and You're developing Hypothyroidism and symptoms associated with it.
Your lab tests may represent middle of this swing, and thus TSH is not really the most accurate diagnostic test.
It's important to note that TSH is useful but better way to diagnose is to check full Thyroid Panel and have a look at free T3 and free T4.
What to Do If Symptoms Persist?
1. Make sure Your doctor analyses Full thyroid Panel, not just TSH.
2. Consider Other Levothyroxine Brands or Changing the medication type.
3. Consider checking the adrenal glands (by testing cortisol) and pituitary gland health.
4. Consider under-conversion of T4 into T3 (active form).
5. Consider checking Thyroid-binding globulin (TBG). It can be raised by estrogen dominance. It can be also decreased by high levels of testosterone levels. This condition often occurs in women with PCOS and insulin resistance.
6. Consider thyroid resistance. It can be caused by elevated homocysteine levels and genetic factors. We don’t have a method for testing the function of thyroid hormone receptors on cells and tissues. However, some tests like testing for HPA axis can be useful as chronic cortisol levels and stress usually contribute greatly to the resistance.
The standard TSH testing or even Full Thyroid Panel can be sometimes insufficient for detecting the cause of the thyroid dysfunction.
Even if all the labs in range, a patient can still be experiencing symptoms of thyroid disorder.
In addition to TSH testing and Full Thyroid Panel, we should always listen to the patient's symptoms.
Sometimes, a patient has been just diagnosed, so his TSH values may be swinging, especially in Hashimoto's.
A patient can also have other underlying problem, like HPA axis dysfunction due to high cortisol, high testosterone or estrogen, blood sugar dysbalance, poor gut health or deficiencies of iron and selenium
It can all affect the thyroid gland, which will sometimes not show up in the basic Thyroid Panel lab test.