top of page

Diagnosis of an underactive thyroid (hypothyroidism) is made based on a combination of thyroid blood test results, symptoms and several other factors.

Symptoms for hypothyroidism are non-specific, meaning there can be many other reasons you are experiencing what you are experiencing. In order to get the right diagnosis your doctor will need to draw some blood to confirm the diagnosis.


Hypothyroidism can be detected by two important readings:

  • TSH Test - Thyroid-stimulating hormone (TSH) is a hormone that stimulates the thyroid to produce thyroid hormone. If you have an abnormally high level of TSH, it could mean you have hypothyroidism.

  • T4 (thyroxine) Test - The thyroid gland produces T4 (thyroxine) which is a type of thyroid hormone. The T4 measured in the blood, in combination with a TSH test, can let your doctor know how your thyroid is functioning.


  • 0.5 – 3.0 mIU/L is the normal range for TSH, for most people (there may be a slight variation depending on the laboratory).

  • If TSH measures is more than 4.0 mU/L, a T4 test will help verify the results. When TSH is more than 4.0/mU/L with a low T4 level, this indicates hypothyroidism.

  • If your TSH is more than 4.0 mU/L and your T4 level is normal, your doctor might have to test your blood for anti-thyroid peroxidase (anti-TPO) antibodies (proteins made by the body to damage the thyroid). When these antibodies are present, it could suggest an autoimmune thyroid disorder, which is a risk factor for developing hypothyroidism. If you have these proteins in your blood, you will need to test your TSH at least once per year.

These blood results will assist your doctor when it comes to prescribing the right dosage of the right medication. Please speak to your doctor for more information about your blood results.


Written by Dr Ruusa Shivute | Health Window

Reference: Watt, T., et al., Quality of life in patients with benign thyroid disorders. A review. Eur J Endocrinol, 2006. 154(4): p. 501-10.

March 18, 2021 |  Categories: Health WindowHypothyroidism

bottom of page