CLINICAL RESEARCH Thyroid Insuf ciency. Is TSH Measurement the Only Diagnostic Tool?

Purpose: To evaluate and compare laboratory indices of thyroid function. Design: Practice-based retrospective study of patients ’ records. Materials and Methods: The records of all hypothyroid patients seen in a private practice in Antwerp, Belgium, between May 1984 and July 1997 were reviewed. Only records with insuf cient data were excluded; 832 patients were included in the study. Of these, 287 could also be followed during replacement therapy. Results: A score of 8 main symptoms of hypothyroidism, serum thyroxine radio-immunoassay (T4-RIA), serum T4-RIA/thyroid binding globulin (TBG), 24 h urine free triiodothyronine (T3) were considered before and after treatment. The score of these 8 main symptoms is a reliable expression of their illness in 97 % of hypothyroid patients. 24 h urine free T3 correlates better with the clinical status of hypothyroid patients (R2 5 0.30) than serum T4-RIA (R2 5 0.12), and even better than T4-RIA/TBG (R2 5 0.19). Other investiga-tors were unable to nd any correlation between serum thyroid stimulating hormone (TSH) or serum free T4 and thyroid symptoms. The dosage of natural desiccated thyroid (NDT) has a correlation with 24 h urine T3 of R2 5 0.50. Conclusions: In this study symptoms of hypothyroidism correlate best with 24 h urine free T3