Screening for thyroid disease in women greater than or equal to 50 years of age seeking hospital care: influence of common nonthyroidal illness on serum free thyroxin as determined by analog radioimmunoassay.

摘要

We determined free thyroxin (fT4; analog radioimmunoassay) and thyrotropin in serum of women greater than or equal to 50 years of age who were attending a medical casualty ward (n = 363) or a medical outpatient clinic (n = 496), in order to estimate the prevalence of low fT4 results associated with nonthyroidal illness and to screen for previously unknown thyroid disease. Individuals with results outside stated limits were followed up within two to four weeks. Only about 5% of the women seeking acute medical care showed a decrease in fT4 concentration in association with a normal thyrotropin concentration. As expected, this combination was even less common in outpatients. We found a prevalence of previously undiagnosed thyroid disease of clinical significance of 0.8% in medical acute-care cases, 1.8% in medical outpatients. For this clinical setting we regard the simple analog technique as acceptable in spite of the low values reported for some hospitalized patients with nonthyroidal illness.