RESUMO
OBJECTIVES: To compare blood thiamine concentrations, echocardiography findings, and plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels in infants with clinically diagnosed beriberi and healthy matched controls, and to evaluate changes after thiamine treatment. STUDY DESIGN: Sixty-two Cambodian infants (20 cases and 42 controls), aged 2-47 weeks, were enrolled in this prospective study. Echocardiography and phlebotomy were performed at baseline and after thiamine treatment. RESULTS: Both cases and controls were thiamine-deficient, with median blood thiamine diphosphate (TDP) concentrations of 47.6 and 55.1 nmol/L, respectively (P = .23). All subjects had normal left ventricular ejection fraction. The median NT-proBNP concentration in cases (340 pg/mL [40.1 pmol/L]) was higher than previously reported normal ranges, but not statistically significantly different from that in controls (175 pg/mL [20.7 pmol/L]) (P = .10), and was not correlated with TDP concentration (P = .13). Two cases with the lowest baseline TDP concentrations (24 and 21 nmol/L) had right ventricular enlargement and elevated NT-proBNP levels that improved dramatically by 48 hours after thiamine administration. CONCLUSION: Only a minority of thiamine-deficient Cambodian infants demonstrate abnormal echocardiography findings. Thiamine deficiency produces echocardiographic evidence of right ventricular dysfunction, but this evidence is not apparent until deficiency is severe. NT-proBNP concentrations are mildly elevated in sick infants with normal echocardiography findings, indicating possible physiological changes not yet associated with echocardiographic abnormalities.
Assuntos
Peptídeo Natriurético Encefálico/sangue , Fragmentos de Peptídeos/sangue , Deficiência de Tiamina/complicações , Tiamina Pirofosfato/uso terapêutico , Disfunção Ventricular Esquerda/etiologia , Povo Asiático/estatística & dados numéricos , Beriberi/sangue , Beriberi/complicações , Beriberi/etnologia , Biomarcadores/metabolismo , Estudos de Casos e Controles , Ecocardiografia Doppler/métodos , Feminino , Seguimentos , Testes de Função Cardíaca , Humanos , Lactente , Recém-Nascido , Masculino , Valores de Referência , Medição de Risco , Índice de Gravidade de Doença , Deficiência de Tiamina/sangue , Deficiência de Tiamina/tratamento farmacológico , Deficiência de Tiamina/etnologia , Tiamina Pirofosfato/sangue , Resultado do Tratamento , Disfunção Ventricular Esquerda/diagnóstico , Disfunção Ventricular Esquerda/etnologiaRESUMO
OBJECTIVES: To test the hypothesis that heavy metal toxicity and consumption of thiaminase-containing foods predispose to symptomatic thiamine deficiency. STUDY DESIGN: In a case-control study, thiamine diphosphate (TDP) blood concentrations were measured in 27 infants diagnosed with beriberi at a rural clinic, as well as their mothers and healthy Cambodian and American controls. Blood and urine levels of lead, arsenic, cadmium, mercury, and thallium were measured. Local food samples were analyzed for thiaminase activity. RESULTS: Mean TDP level among cases and Cambodian controls was 48 and 56 nmol/L, respectively (P = .08) and was 132 nmol/L in American controls (P < .0001 compared with both Cambodian groups). Mean TDP level of mothers of cases and Cambodian controls was 57 and 57 nmol/L (P = .92), and was 126 nmol/L in American mothers (P < .0001 compared with both Cambodian groups). Cases (but not controls) had lower blood TDP levels than their mothers (P = .02). Infant TDP level decreased with infant age and was positively associated with maternal TDP level. Specific diagnostic criteria for beriberi did not correlate with TDP level. There was no correlation between heavy metal levels and either TDP level or case/control status. No thiaminase activity was observed in food samples. CONCLUSIONS: Thiamine deficiency is endemic among infants and nursing mothers in rural southeastern Cambodia and is often clinically inapparent. Neither heavy metal toxicity nor consumption of thiaminase-containing foods account for thiamine deficiency in this region.