Thiamin status, diuretic medications and the management of congestive heart failure

Abstract

Thiamin deficiency in malnourished patients is known to have adverse cardiovascular effects: peripheral vasodilation leading to high output cardiac failure, biventricular low output failure and retention of sodium and water resulting in edema. Results from previous investigations suggest increased risk of thiamin deficiency in patients with congestive heart failure (CHF) on long term loop diuretics due to excessive urinary excretion. The purpose of this study was to assess the prevalence of thiamin deficiency in patients with CHF who are receiving loop diuretic therapy. This was a prospective investigation of thiamin status including dietary assessment and biochemical measurements via transketolase activity (TKA) with and without thiamin pyrophosphate (TPP) cofactor in consecutive patients of a cardiology clinic. Thiamin status was measured biochemically by in vitro erythrocyte TKA before and after addition of exogenous TPP. TPP effect (TPPE) was expressed as percent stimulation of TKA with exogenous TPP. Thiamin status was defined by TPPE as: normal 0–15%, mild deficiency 15–25%, severe deficiency >25%. Dietary assessment was obtained by a quantitative food frequency questionnaire of thiamin-rich foods. Adequacy of dietary intake was classified as: normal >30 servings/week, mild inadequacy 20–30 servings/week, severe inadequacy <20 servings/week. Thirty-eight patients (mean and median of 56 years; range 20–79 years); 29 males, 9 females; and 30 white, 8 nonwhite were included in the study. Inclusion criteria: 18–80, New York Heart Association class II, III, IV, left ventricular ejection fraction <40%, Lasix 80mg/day or Bumex 2mg/day, treatment with ace inhibitor, nitrate digoxin, zaroxolyn was acceptable. Measurements were compared with values obtained from nine control subjects. Logistic regression was used to evaluate relationships between thiamin status and cardiac function, clinical laboratory data, patient characteristics and confounding variables. Biochemical evidence of thiamin deficiency was found in 21% (838) of patients. Overall prevalence of dietary thiamin inadequacy was 20%. Of the eight patients with biochemical evidence of thiamin deficiency, seven had levels of dietary thiamin which appeared to meet or exceed RDA levels. Biochemical evidence of thiamin deficiency was found to be more likely to occur in males (vs. females) and nonwhites (vs. nonwhites) (p=0.005). In conclusion, thiamin deficiency may occur in one-fifth of patients with CHF in a cardiology clinic. Of this group, male and nonwhite CHF patients appear to be at highest risk for thiamin deficiency. Dietary intake of thiamin-rich foods does not appear to prevent biochemical thiamin deficiency in this population. Status of other micronutrients may also be affected by loop diuretics and deserves further study.