Thiamine deficiency in congestive heart failure patients receiving long term furosemide therapy.

OBJECTIVE: To assess the presence of thiamine deficiency in congestive heart failure patients receiving furosemide therapy. DESIGN: Prospective, biochemical analysis of thiamine status was performed in outpatients and inpatients of the University of Ottawa Heart Institute. SUBJECTS: Thirty-two patients with congestive heart failure who received at least 40 mg/day of furosemide were included. Patients were then separated into two groups depending on whether the dose of furosemide was greater than or equal to 80 mg/day. METHODS: The primary measure was actual thiamine status as assessed by the erythrocyte transketolase enzyme activity and the degree of thiamine pyrophosphate effect. RESULTS: Biochemical evidence of severe thiamine deficiency was found in 98% (24 of 25) patients receiving at least 80 mg/day of furosemide and in 57% (four of seven) of patients taking 40 mg furosemide daily, odds ratio (OR) 19.0 (1.13