First Phase in Objective Evaluation of New Diagnostic Tests Application to Thyroid Uptake of 131I

Abstract

Categories of thyroid function were defined by radioiodine uptake measurement performed on 90 patients referred to a radioisotope service for suspected thyroid abnormalities. By a modification of Bayes' theorem the probability of high, low or normal uptake was estimated by a quantitative analysis of the clinical symptoms and signs obtained prior to performance of the radioiodine test. The contribution of the laboratory test was defined in terms of the uncertainty with which the clinical syndrome alone predicted the laboratory result. The application of these principles to a single laboratory test was used to illustrate their more general applicability in relating laboratory procedures to the entire diagnostic process, beginning with the clinical examination of the patient