Fatigue, endocrinopathies, and metabolic disorders.

Fatigue is a frequent reason for seeking medical attention. Endocrine dysfunction is a common etiology of fatigue. In fact, thyroid function is usually one of the first explanations on the list of possible diagnoses. The symptoms associated with endocrinopathies are frequently "nonspecific," and psychiatric disease or psychological disorders need to be differentiated. Often, this can be accomplished using biological measures of hormone function, such as measures of thyroid, pituitary, parathyroid, and adrenal hormone levels. The field of endocrinology is highly dependent on an algorithmic approach to differential diagnosis using hormone levels as the guide. The use of self-reports helps identify at-risk patients, and raises suspicions about whether there is an abnormality, but diagnosis is dependent on laboratory values. Metabolic abnormalities, such as hyper- or hypoglycemia, dyslipidemia, and gonadal dysfunction can also contribute to fatigue. A better understanding of the interactions among hormones, their releasing factors, and regulation of inflammation will help identify abnormalities early and help distinguish endocrinopathies from other causes of fatigue. Early identification of these abnormalities may reduce end-organ damage and improve treatment strategies.