Evaluation of the Thyroid Disease

Abstract

Thyroid abnormalities are commonly found in clinical practice, and their detection by either the physician or the patient always raises the concern of the disease. In addition, many new tests are available to aid the physician in the clinical assessment of thyroid diseases. Algorithms and guidelines for thyroid function testing generally are based on pathophysiologic principles and practice consensus; few have been derived from actual practice outcomes data. This article discusses the clinical and laboratory diagnosis of a spectrum of thyroid disease, ranging from those in whom the diagnosis is obvious after initial history and physical examination to those without typical symptoms or signs in whom the diagnosis is made solely by abnormal laboratory results. Over the past decade it has been generally accepted that the serum thyrotropin represents the best biochemical marker of thyroid function when measured using an adequately sensitive assay. Subclinical hypothyroidism is defined as normal serum thyroid hormone and elevated serum thyrotropin concentrations. Subclinical thyrotoxicosis is defined as low serum thyrotropin and normal serum thyroid hormone concentrations. It must be distinguish from nonthyroidal illness and secondary hypothyroidism. The most common causes are excessive thyroid hormone therapy, autonomously functioning thyroid adenomas, multinodular goiter and Graves’ disease, but many patients have no evident thyroid disease. Thyroid nodules are commonly found in clinical practice, and their detection by either the physician or the patients always raises the concern of cancer. The application of fine-needle aspiration biopsy, the availability of high-resolution ultrasonography, the introduction of new highly sensitive thyrotropin therapy have modified thyroid nodule management.