The Importance of Regular Thyroid Function Testing While on Levothyroxine

Importance Regular

Your thyroid is an incredibly important part of your overall health, because it helps regulate hormones, including those that influence metabolism and body temperature, as well as growth and development. If your thyroid gland is underactive, it can cause a range of symptoms, including changes in weight, energy levels, and mood, as well as feeling cold, constipation, and fatigue. Levothyroxine, a synthetic thyroid hormone, can help treat issues related to an underactive thyroid that are caused by low levels of thyroid stimulating hormone (TSH).

Why Regular Thyroid Function Testing is Important While on Levothyroxine

Regular thyroid function testing is important for anyone taking levothyroxine to help ensure that the dosage is correct and to help monitor the effects of treatment. Thyroid stimulating hormone (TSH) tests can help determine if the dosage of thyroid hormone needs to be adjusted and help your doctor identify any signs of thyroid dysfunction. Testing your thyroid function while on levothyroxine is the best way to manage an underactive thyroid gland and helps ensure that your symptoms improve, as well as prevent related complications.

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Key Signs that You May Need a TSH Test

If any of the following signs or symptoms are present, it is important to schedule a TSH test to ensure proper levels of thyroid-stimulating hormone and monitor the effects of levothyroxine:

  • Weight gain or weight loss
  • Fatigue
  • Difficulty sleeping
  • Mood swings or anxiety
  • Decreased cognitive functioning
  • Dry skin and brittle hair or nails

The Risk Factors Associated with Not Testing TSH Levels While on Levothyroxine

When a patient is prescribed levothyroxine but doesn’t undergo regular TSH tests, they run the risk of having too little or too much of the synthetic thyroid hormone in their system. If the amount of levothyroxine in the body is too high, it can cause symptoms such as insomnia, rapid heartbeat, weight loss, and irritability. Conversely, if the amount of medication is too low, symptoms like fatigue, weight gain, and constipation can occur. Therefore, periodic thyroid function tests are extremely important for those taking levothyroxine.


For individuals taking levothyroxine to treat an underactive thyroids, regular thyroid function testing is absolutely essential for effective treatment. By regularly testing thyroid stimulating hormone (TSH) levels, your doctor will be able to ensure that the dosage of medication is correct and that its therapeutic effects are as expected. Failing to perform regular TSH tests can lead to elevated or decreased levels of levothyroxine, which can cause numerous side effects or even exacerbate existing symptoms. Therefore, it is important to speak to your doctor about having a TSH test to help manage an underactive thyroid.