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How is Hypothyroidism Diagnosed?

Hypothyroidism can be diagnosed with a simple TSH blood test.

The TSH blood test measures the amount of Thyroid Stimulating Hormone (TSH) in your blood.

It is estimated that many people with thyroid disease don't even know they have it. This may be because symptoms develop slowly and often mimic other conditions.

Infographic on cases of hyperthyroidism:

In most cases of hypothyroidism, there are:

  • High TSH levels
  • Lower levels of thyroid hormones.

Since thyroid hormone and TSH levels may change throughout life, they should be checked starting at the age of 35 and every five years thereafter. Some people may need to get their TSH levels tested more often than others. Learn More.

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TSH Levels

When you suffer from hypothyroidism, your TSH levels will be high because your body can’t make enough of the thyroid hormones T3 and T4. When your pituitary gland gets the signal that your body needs more thyroid hormones, it overproduces TSH in an attempt to stimulate your thyroid to release thyroid hormones.

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T4 Levels

Sometimes it's necessary to test the amount of T4 in your blood and check for thyroid autoantibodies to confirm a diagnosis. If the thyroid appears to have an abnormal shape, a thyroid scan or ultrasound may be performed.

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The Difficulty with Diagnosing Hypothyroidism

Hypothyroidism is fairly easy to diagnose through a simple TSH blood test; however, it is estimated that up to 50% of people with thyroid disease don’t even know they have it. This may be due to the fact that symptoms develop slowly and often mimic other conditions.

For example, depression and menopause share some similar symptoms with hypothyroidism, such as fatigue, weight gain and depressed mood.

Timing may also be a factor that confuses a diagnosis of hypothyroidism. It is more common in people over 50, in women who have recently given birth and during menopause. Older people may wrongly think they are just “feeling their age” and pregnant women and new mothers may attribute their symptoms to the stress of imminent or recent childbirth.