Interpretation of thyroid function tests

Abstract

Thyroid gland disorders are common and can affect up to 10% of the general population. In many cases the symptoms can be nonspecific, so the physician in search for a thyroid disorder should reach a functional and anatomical diagnosis. Serum measurements of thyroid hormones confirm if there is an excess, a deficit, or if concentrations are normal. For this, reference ranges of the local population, and specifically by age groups, are required for a correct interpretation of thyroid function tests. Thyroid hormones play a fundamental role in the endocrine system, control of the general metabolism of the body, neural development, normal growth and maturation of bones, as well as in cardiovascular and renal functions, among others. In this review, the most relevant thyroid tests will be described, starting with the biosynthesis and secretion of thyroid hormones, and continuing with an approach to reach an initial diagnosis. Finally, the most important aspects of the di-fferent thyroid patterns will be mentioned. It is beyond the scope of this review, to describe the treatment for thyroid disorders.