Hypothyroidism: How Do You Diagnose It?

Diagnosing hypothyroidism early on can help prevent the many complications associated with it. However hypothyroidism cannot be diagnosed on symptoms alone - read on to find out which specific tests are needed

Posted on December 8, 2021 ·

BY Team Veera

Medically Reviewed

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When you think of fatigue, loss of appetite, dry skin or hair loss — you would usually associate it with stress or a hectic lifestyle.  But did you know that these common symptoms are also associated with hypothyroidism? Although having these symptoms doesn’t necessarily mean you have hypothyroidism but what it does mean is that you cannot simply diagnose hypothyroidism based on symptoms alone some additional tests are required before you get a formal diagnosis.

Diagnosing hypothyroidism early on, especially in newborn babies, pregnant women or people who have a family history of hypothyroidism can prevent it from worsening.

Hypothyroidism diagnosis

Since most symptoms of hypothyroidism are common complaints that a lot of people with a normally functioning thyroid can have diagnosis is usually based on a combination of your symptoms, physical examination and blood tests.

Medical history

One way you can assess if the symptoms are due to hypothyroidism is to think if the symptoms have always been there or there is a change in the way you feel. When you speak with your doctor, it’s important to give all information about your symptoms, medical and family history. This can include:

  • Any changes in your health in the past or any recent observations
  • If you have ever undergone thyroid surgery
  • If you have received radiation to your head or neck for cancer treatment
  • If you are currently on certain medications that can interfere with the normal functioning of your thyroid such as medicines prescribed for heart problems, psychiatric conditions or cancer
  • Lastly, if your immediate family member or a close relative has hypothyroidism or any form of thyroid disorders

Physical examination

Once you have discussed your medical and family history, your doctor will perform a physical examination especially to check your thyroid by placing fingers near the thyroid gland to check for any enlargement or tenderness. Also, in cases where hypothyroidism has gone untreated for years, certain symptoms such as dry skin, cold intolerance, slow heart rate and swelling may also be seen.

Blood tests

Diagnosis of hypothyroidism heavily depends on blood tests and is shown to be the most effective method for early detection as well.

Thyroid Stimulating Hormone (TSH) test


TSH is a hormone produced by your pituitary gland (located at the base of your brain) to instruct your thyroid on how much thyroid hormone to make. So basically your thyroid functions under the instructions of the TSH secreted by the pituitary.Thyroxine or T4 is the main hormone produced by your thyroid gland in response to TSH. When your thyroxine levels are low in the blood, the pituitary gland sends out enough TSH to tell your thyroid gland to make more thyroxine. So the lower the thyroxine levels go, the higher the TSH levels. The same is also true when there is excess of thyroxine levels in blood, in which case the TSH levels drop.This makes the TSH test a simple and a sensitive way for diagnosing and monitoring hypothyroidism.So with hypothyroidism, although the pituitary gland is sending out TSH to maintain thyroxine levels, your thyroid is unable to produce enough thyroxine and as a result there is an elevated level of TSH found in the blood. Although most labs will have a common ‘normal’ range for TSH, there might be slight differences. The normal range for TSH is approx 0.4 mU/L to 4.0 mU/L. If the TSH level is above 4.0 mU/L, it can indicate hypothyroidism.

T4 or thyroxine test


T4 is the main hormone produced by the thyroid gland and circulated in blood before it is converted to T3 (active form of thyroid hormone). Measuring free T4 levels and the free T4 index are important tests that accurately reflect how your thyroid gland is functioning when combined with the TSH test. So if you have an elevated level of TSH and low free T4 levels, it indicates hypothyroidism.

Thyroid antibody test


Your immune systems’ role is to protect your body from bacteria and viruses by producing antibodies. But sometimes your antibodies can attack its own tissues and organs. Hashimoto’s thyroiditis is the most common cause of hypothyroidism where certain antibodies attack the thyroid itself. This can cause the thyroid cells to be damaged and affect its ability to produce thyroxine. Two common thyroid antibodies are anti-thyroperoxidase and anti-thyroglobulin antibodies. Such antibody tests are helpful in finding out the cause of hypothyroidism. So if you are positive for thyroid antibodies you could have an autoimmune thyroid disorder

However, before you get a thyroid function test done, you should be aware that there are certain medications that can interfere with the accuracy of the results. Biotin is one such common supplement that can show up as abnormal thyroid levels, when in reality they are normal in the blood. It is advised to not take biotin for 2 days before you draw your blood for the thyroid test. It is important to inform your doctor of any medications you’re currently on to avoid false positives. 

Having your TSH levels measured is not only an important part of diagnosis but is also important in managing and treating hypothyroidism. Like any chronic condition, getting proper diagnosis opens up an array of treatment options that will help you feel better again!

Disclaimer: Content on Veera is provided for informational purposes only and is not intended as medical advice, or as a substitute for medical advice given by a physician

Verified by Dr. Iris Lee

Fellow in Reproductive Endocrinology and Infertility, University of Pennsylvania

Dr. Lee is a fellow in reproductive endocrinology and infertility at the University of Pennsylvania. She completed medical school and residency training at the University of Pennsylvania as well. Her work focuses primarily on PCOS, particularly the metabolic and mental health implications. Outside of work, she enjoys baking, reading, and spending time with her husband and two puppies.

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