TSH is the hormone produced by your pituitary gland to control the function of your thyroid gland. High TSH value suggests that you have an underactive thyroid gland. There are so many controversies regarding the normal level of TSH.
According to the National Health and Nutrition Examination Survey (NHANES III) the mean TSH in apparently normal, healthy participants is 1.4 uIU/mL.
Based upon the results of NHANES III, The National Academy for Clinical Biochemistry has recommended since 2002 that a serum TSH level between 0.5-2.0 uIU/mL be considered the optimal therapeutic target for replacement treatment of hypothyroidism.
according to the American Thyroid Association (ATA), Normal TSH levels typically fall between 0.4 and 4.0 milliunits per liter (mU/L) , But TSH value above 2.5 should not be taken as normal and considered as a warning sign. It is a stage we can count as Subclinical hypothyroidism.
There are several studies showing that any TSH above 2.5 is associated with metabolic syndrome, insulin resistance, elevated fasting triglycerides, elevated blood pressure, and higher body mass index. Here is one representative study:
This study found that subjects with a TSH in the upper “normal” range (2.5-4.5) had a significantly higher BMI, higher fasting triglycerides, The study concluded that a TSH above 2.5 is associated with an unfavorable metabolic profile.
If your TSH is above 2.5 it is my opinion you should first NOT accept this as normal and always go for complete Thyroid profile:
- Total T4 and T3 and a
- Free T4 and T3. and
- Anti-thyroid peroxidase (anti-TPO),
- Thyroglobulin Antibodies (TgAb) to rule out the Auto-Immune disease of Thyroid.