POOR POSITIVE PREDICTIVE VALUE OF LOW SENSITIVE THYROTROPIN ASSAY LEVELS FOR HYPERTHYROIDISM IN NURSING-HOME RESIDENTS

We assessed the positive predictive value of a low thyrotropin (TSH) l evel on sensitive TSH (STSH) assay as an indicator of hyperthyroidism. In 742 determinations on nursing home residents who were not taking t hyroid hormone, we identified 15 with low TSH levels. None of the resi dents had a completely suppressed (undetectable) TSH level upon initia l testing or an elevated total triiodothyronine (T3) or thyroxine (T4) level. Half the patients in whom total T3 was measured had low levels . Of 11 surviving residents, four subsequently had a normal TSH level and six others had a normal free T4 level. Only one patient had a slig ht elevation of the free T4 level. None of the residents were diagnose d as having hyperthyroidism.