| Alterations of serum thyroid hormone levels in nonthyroidal illnesses are the net effect of disturbances in thyroid hormone metabolism and "artifacts" of laboratory measurements which occur in sera from sick patients (1-6). These changes in serum thyroid hormone levels are common, and may mimic or mask biochemical features of hypothyroidism or hyperthyroidism. By definition, nonthyroidal disorders reversibly alter the hypothalamic-pituitary- thyroid axis as well as peripheral thyroid hormone metabolism, in the absence of concurrent hypothalamic, pituitary or thyroid disease. Recognition of changes in serum thyroid hormone levels induced by nonthyroidal disorders is essential to accurately diagnose and treat hypothyroidism and hyperthyroidism in sick patients (3-6). |
