Thyroid stimulating hormone (TSH) is the hormone produced by your pituitary gland to control the function of your thyroid gland. A high TSH means your pituitary senses that your thyroid is underactive.
Many labs are misleading physicians by using outdated ranges of normal for TSH, thus preventing doctors from giving their patients the most effective thyroid treatment they need.
The National Health and Nutrition Examination Survey (NHANES III) demonstrated that 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.
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, and their likelihood for fulfilling the ATP III criteria of the metabolic syndrome was 1.7 fold increased. The study concluded that a TSH above 2.5 is associated with an unfavorable metabolic profile. Ultimately you need more than the TSH to get a full picture of the health of your thyroid. We need to see your Free T4 and Free T3 as well. Also thyroid antibodies should be tested and retested because they often come back as a false negative.
I have worked with MANY patients who were told their thyroid is “normal” only to find out when we looked at their labs together they had full blown Hashimoto’s (autoimmune hypothyroidism) and their thyroid was slowly being destroyed. You CAN get your life back by working with a qualified practitioner. Be an advocate for your own body, trust your senses, you know when something is off.