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Limitations of the TSH Test

How many times have you heard from your endocrinologist that your TSH is correct…even though it was somewhere between 2.8 - 4.0 μIU/ml!

It just does not make sense. Although, your doctor tells you that your values are in range you still experience:

  • weight problems

  • lack of energy

  • brain fog

  • anxiety

  • mood changes

  • hair, skin & nails problems

  • & many other symptoms


So, you wonder, why? why are you not feeling better

You see, conventional doctors use the TSH test to determine if you have a thyroid disorder and as a measure by which to dose your thyroid medications.


However, this test can often be misleading for a few reasons:

  1. The reference range of TSH is far too broad! In fact, for many physicians, TSH of 2.9 or 3.5 is good, while in reality it’s not optimal and you may still be having symptoms of hypothyroidism. On the other hand, functional medicine doctors defined optimal reference ranges to be between 1 and 2 μIU/ml, for a healthy person not taking thyroid medications and most patients feel best with a TSH between 0.5-2μIU/ml.

  2. Reference ranges take into account the values of 95% of the population. If you are in the 5%, you may experience symptoms of hypothyroidism or hyperthyroidism with TSH values that are considered “normal”. This means that a doctor has to analyze also other labs, not just your TSH.

  3. Dopamine mimicking medications, like bromocryptine, can lower your TSH. This is important to take into consideration while looking at the TSH result.

  4. Glucocorticoid medications like prednisone can suppress the TSH hormone, even when T3 and T4 levels are low, leading to central hypothyroidism. This is important to take into consideration while looking at the TSH result.

  5. Adrenal glandulars and adrenal hormones (especially in higher doses) can suppress the TSH. This is important to take into consideration while looking at the TSH result.

  6. Metformin which is used for diabetes may also alter TSH is some patients. This is important to take into consideration while looking at TSH result.


Take-Home Message?


If anyone ever told you that your TSH is “good”, while being above 3, just because they used the old reference range or/and don’t understand the importance of the optimal TSH i.e. 0.5-2μIU/ml (preferably below 1), that may be the reason of your chronic hypothyroidism symptoms. We encourage you to take charge of your health and in this situation change your doctor, so you can finally start to feel better!













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