The role of thyroid tests in handling of patients in general practice. A phenomenologic study.

During a period of 2 months thyroid function tests, performed on out-patients referred to the laboratory from general practitioners, were studied. The relative informative value of the tests was estimated in relation to the reasons given for requesting the tests. In 86% of the samples from patients with no history of earlier thyroid disease the conventional thyroid tests were found within the reference intervals. 3% showed a definite abnormal pattern of values. In 11% the results were in some way abnormal. In the group of patients with earlier history of thyroid disease 50% of the tests were abnormal. The relative merits of adding a sensitive TSH assay test were analyzed, and it was estimated whether using the sensitive TSH as a first-line discrimination test would add or subtract information compared to the conventional thyroid function tests. It was concluded that in the situation where the general practitioner wants laboratory information of thyroid parameters on patients in order to make decisions on the further handling of the patient, the sensitive TSH test is of limited value as a first-line discrimination test and should be supplemented by other tests.