Biochemical Testing of the Thyroid: TSH Is the Best and Often Only Test Needed – A Review for Primary Care

The 2016 review highlights that Thyroid Stimulating Hormone (TSH) is often the best and only necessary test for thyroid function evaluation in primary care. It discusses the non-specific and common nature of thyroid dysfunction symptoms, such as obesity, mood changes, hair loss, and fatigue, and the challenges they pose in diagnosis and management. The review explains the physiology of the thyroid and the relationship between TSH and free thyroid hormones, emphasizing the importance of understanding individual hormone level set points and the effects of non-thyroidal illness and circadian rhythms on test results. It also addresses the prevalence of subclinical hypothyroidism and the need for reassessment rather than immediate treatment for mildly elevated TSH. The document notes that while TSH is a reliable indicator in most cases, additional testing may be necessary for specific rare conditions. It concludes that despite patient demands for more testing, TSH should remain the primary test for thyroid function assessment in primary care.