This is a question that I get a lot from patients. The answer is often “no”.

They are interested in a second opinion because they are struggling with symptoms that point to a thyroid disorder. They are not convinced that their thyroid is normal, which is what their labs are saying.

Upon review of their lab tests, it turns out not all thyroid hormones were checked. Current standard of care guidelines for thyroid disorder screening only requires testing for thyroid stimulating hormone (TSH). This hormone is not even made in the thyroid so testing for TSH is only part of the picture.

I find testing for hormones made by the thyroid – thyroxine (T4) and triiodothyronine (T3) – in addition to TSH very helpful. TSH is released by the posterior pituitary gland in the brain to provide signals to the thyroid. T4 and T3 also communicate with the brain to influence TSH levels.

Testing for TSH, T4, and T3 collectively provides a more complete picture of thyroid function. It is possible for TSH to be in normal range while T4 and/or T3 to be abnormal.

This explains why many thyroid disorders, especially hypothyroidism, are overlooked. Common symptoms of hypothyroidism include fatigue, weight gain, hair loss, dry skin, constipation, and irregular menstrual cycles.