A simplified scheme for the investigation of thyroid function in chronic liver disease

The investigation of thyroid disease in the presence of chronic liver disease (CLD) is difficult. Conventional tests are influenced by chronic illness and abnormal concentrations of binding proteins. A three tier system is normally used; thyroxine (T4), then T3 or TSH and an index for binding proteins. The recently introduced TSH immunoradiometric assays (IRMA) offer the potential of a single test assessment of thyroid function. This was assessed by the measurement of T4, T3, THBC and the free thyroxine indices in subjects with CLD. Conventional tests showed a high number of abnormal T4 values but binding indices were normal. The TSH-IRMA results were all normal. TSH-IRMA assays are rapid, easy to use and cheap. They remove the uncertainties in assessing thyroid function in CLD and may be the test of choice.