MEDICATION AND LOW SERUM THYROXINE VALUES IN NURSING-HOME RESIDENTS

Background. The nursing home clinician may encounter euthyroid residen ts with low total serum thyroxine (T-4) values associated pith certain medications or nonthyroidal illness (NTI). Hypothyroidism may be inco rrectly diagnosed and thyroid hormone prescribed. Methods. We reviewed all T-4 determinations and individuals with low T-4 and normal thyroi d-stimulating hormone (TSH) levels were identified. Pharmacy and medic al records were reviewed. Results. We reviewed 1,153 T-4 determination s and identified 22 individuals with low T-4 and normal TSH values. Ei ght of the 22 (36%) were being treated with high-dose salicylates, 4 ( 18%) with phenytoin, 3 (14%) with carbamazepine, and 2 (9%) with predn isone (15 mg/day). Three residents were on two of these medications. N one was on prednisone as a single medication. Eight were on none of th e medications, and 5 of these had albumin values of less than or equal to 3.2 g/dL (a marker of NTI). After a low T-4 value was determined i n these individuals, 6 of the 22 Were placed on T-4 replacement with n o documentation of hypothyroidism. In 5 of these, low T-4 level could be attributed to a medication effect. Conclusions. Low total T-4 with normal TSH levels are commonly associated with medications and NTI.