From the Guidelines
Monitoring hypothyroidism involves regular serum TSH tests.
Methods for Monitoring
- The primary screening test for thyroid dysfunction is the serum TSH test 1.
- Multiple tests should be done over a 3- to 6-month interval to confirm or rule out abnormal findings 1.
- Follow-up testing of serum T4 levels can differentiate between subclinical and "overt" thyroid dysfunction in persons with persistently abnormal TSH levels 1.
- Risk factors for hypothyroidism, such as female sex, advancing age, white race, type 1 diabetes, Down syndrome, family history of thyroid disease, goiter, previous hyperthyroidism, and external-beam radiation in the head and neck area, should be considered when monitoring for hypothyroidism 1.
- Subclinical hypothyroidism is associated with poor obstetric outcomes and poor cognitive development in children, but evidence for dyslipidemia, atherosclerosis, and decreased quality of life in adults is inconsistent and less convincing 1.
- The optimal screening interval for thyroid dysfunction is unknown, but the American Thyroid Association recommends measuring thyroid function in all adults beginning at age 35 years and every 5 years thereafter 1.
From the Research
Methods for Monitoring Hypothyroidism
The following methods are used to monitor hypothyroidism:
- Thyroid-stimulating hormone (TSH) level testing, which is the preferred test for initial evaluation of suspected primary hypothyroidism 2
- Free thyroxine (T4) level testing, which is used to further narrow the diagnosis if TSH is abnormal 2
- Triiodothyronine (T3) level testing, which is used if TSH is undetectable and free T4 is normal 2
- Monitoring of TSH levels to assess the adequacy of replacement therapy in primary hypothyroidism 2
- Monitoring of free T4 and T3 concentrations in central hypothyroidism, as TSH levels cannot be used 2
Laboratory Tests
Laboratory tests used to diagnose hypothyroidism include:
- Measurement of thyroid hormones (T3 and T4) in the blood 3
- TSH level testing 4, 2
- Free thyroxine (FT4) measurement, which is integral in the diagnosis and management of central dysfunctions and for monitoring therapy in hyperthyroid patients 5
Treatment Monitoring
Treatment of hypothyroidism typically involves lifelong hormone replacement therapy with synthetic thyroid hormone replacement medication, such as levothyroxine 3. Monitoring of treatment involves: