What is thyroid test?
The usual blood tests done as thyroid test and for checking thyroid function are TSH, T4 and sometimes T3. A blood sample is taken from a vein in the arm and sent off to the laboratory for analysis. Usually the ‘free’ or active portion of T4 and T3 is. Laboratories use reference ranges to compare blood test results with results in the normal healthy population. In pregnancy the serum TSH reference range is different from the general population and should ideally be based on reference ranges derived from healthy pregnant women in the same population.
How can thyroid tests be used to diagnose thyroid disorders?
The doctor will interpret the thyroid tests, together with your symptoms, in order to diagnose whether you have a thyroid disorder, how severe it is, and how to treat it. If your TSH and FT4 results are outside the reference range your doctor may order additional tests.
- If the TSH level is high and the FT4 result is low this suggests an underactive thyroid (hypothyroidism) that requires treatment.
- If the TSH level is low and the FT4 result is high this suggests an overactive thyroid (hyperthyroidism) that requires treatment.
Why is the thyroid test (TSH) test done?
A thyroid test (TSH) test helps doctors determine how well the thyroid gland is functioning. People may require thyroid test (TSH) testing for several different reasons, which we explore in more detail below.
- Symptoms of a thyroid problem: The thyroid test (TSH) helps doctors diagnose common thyroid disorders, such as hyperthyroidism and hypothyroidism. A thyroid test (TSH) may also help indicate other types of thyroid problem, such as: Graves’ disease, Hashimoto’s disease, thyroid nodules, inflammation called thyroiditis, postpartum thyroiditis.
- Already have a thyroid disorder diagnosis: People who have a known thyroid disorder may have regular TSH testing to monitor their condition and the effectiveness of their treatment.
- Pregnancy: Some doctors will recommend that pregnant women have TSH tests to check their thyroid hormone levels. Many experts support testing for thyroid disease in women who are pregnant or thinking of becoming pregnant.
** Newborn babies (in the United States for example) will also often get a routine TSH test for congenital hypothyroidism as part of their screening program.
Reference:
https://my.clevelandclinic.org/health/diagnostics/17556-thyroid-blood-tests
https://www.medicalnewstoday.com/articles/324096.php
http://www.btf-thyroid.org/information/leaflets/34-thyroid-function-tests-guide
