How do you test for an underactive thyroid?


Quick Answer

Testing for an underactive thyroid, also known as hypothyroidism, involves a physical examination then a blood test to confirm a diagnosis, states WebMD. People who suspect that they have an underactive thyroid should see a general practitioner for testing, recommends NHS Choices.

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Full Answer

Doctors normally take a thorough medical history before testing for an underactive thyroid, notes WebMD. Symptoms such as feeling increasingly tired, weight gain, constipation or dry skin may indicate an underactive thyroid, according to Mayo Clinic. In addition, doctors normally test people with goiter or previous thyroid problems for hypothyroidism. Hypothyroidism is common in older women, the reason that some doctors recommend screening for it during their routine physical examinations. The blood tests for an underactive thyroid are thyroid-stimulating hormone, or TSH, and thyroxine, or T4, measurement tests, states WebMD.

A high level of TSH and a low level of T4 in blood indicate an underactive thyroid, notes Mayo Clinic. An underactive thyroid produces less thyroid hormone, causing the pituitary gland to release more TSH to stimulate it. Testing helps doctors diagnose thyroid disorders before patients experience symptoms. Testing for an underactive thyroid is important because it helps doctors give patients correct dosage of medication. Doctors may also carry out antithyroid antibody tests to determine if patients have Hashimoto's thyroiditis, an autoimmune disease which causes attacks on the thyroid gland, notes WebMD.

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