Influence of diuretic therapy on thiamin blood levels in patients with heart failure

BACKGROUND: The importance of micronutrients such as thiamine known since its deficiency is associated with the development of high-output heart failure (HF). Several studies show the influence of diuretic therapy in thiamine blood levels. OBJECTIVES: assess whether the use of furosemide alone or in combination with spironolactone (spiro) can determine different thiamine blood levels in patients (pt) with HF. To determinat whether thiamine blood levels were influenced by nutritional factors, comorbidities and other drugs. METHODS: Study 1 - cross-sectional analysis (previous use of furosemide alone or with spiro) of 22 HF pt (NYha class III/IV) divided in two groups: I - with spiro (n=11) and II - without spiro (n=11); Study 2 - randomized, open-label, with three parallel groups of 53 HF pt divided into group "without diuretics" (n=15), "with diuretic" (n=15) (use of furosemide until day 90 and then adding spiro from day 90 until day 180) and "with spiro" (n=23) (using furosemide and spiro through all study). Patients were scheduled to three visits: day 0, day 90 and day 180, and blood samples were collected for thiamine and other tests, as well as clinical analysis. Thiamine levels were determined using an apoenzyme recombination method and high-performance liquid chromatography. The tests used were t-Student, chi-square, Mann-Whitney, Kruskal-Wallis, Spearman correlation, and as the variance was about three times higher than estimated, we used a robust Monte Carlo simulation. RESULTS: in study 1, group I and II were similar regarding food intake, daily furosemide doses (I=110.9+-30.2 vs II=105.5+-26.9 mg; p>0.05) and demographics. Pts in group I (277.2+-89.8) showed significantly higher thiamine levels when compared to pts in group II (154.7+-35.7) (p<0.001). No other variables were associated with thiamine. In study 2, the groups were also similar regarding clinical and laboratory assessments. We found no statistical differences in thiamin blood levels...