Academic journal article Journal of Health Population and Nutrition

Urinary Retinol Excretion in Children with Acute Watery Diarrhoea

Academic journal article Journal of Health Population and Nutrition

Urinary Retinol Excretion in Children with Acute Watery Diarrhoea

Article excerpt

INTRODUCTION

Vitamin A deficiency is a major public-health problem in children with infection in developing countries (1). Even in developed countries where vitamin A status of population is supposed to be adequate, acute illnesses, such as measles, respiratory syncytial infection, and other respiratory infections, can decrease serum concentrations of vitamin A (retinol) significantly (2,3). Mechanisms of vitamin A deficiency during infection are not conclusive. Previous studies have focused on mechanisms, including inadequate intake (4), decreased absorption (5,6), and increased demand of vitamin A during infection (7). More recently, urinary excretion of retinol has been shown to be one of the major routes of vitamin A loss during infection (8-11).

Results of an earlier study by Lawrie et al. showed evidence of frequent urinary excretion of vitamin A in subjects with respiratory diseases (12). Later, results of studies by Stephensen et al. in adults with septicaemia and pneumonia showed that urinary retinol excretion is positively associated with fever and with severity of infection (8). Alvarez et al. showed significant amounts of urinary retinol excretion in Peruvian children with watery diarrhoea, particularly due to rotavirus infection (9). We observed previously that urinary retinol excretion could be a significant mechanism of vitamin A loss in children with shigellosis (11). We also showed that impaired kidney tubular re-absorption of low-molecular weight proteins, such as retinol-binding protein (RBP) might cause urinary retinol loss in case of shigellosis. However, more data are needed to demonstrate if urinary retinol loss is a significant mechanism of vitamin A deficiency during some other common childhood infections and to understand the pathophysiology of such losses. The aims of this study were: (i) to determine the extent of urinary retinol loss in children with acute watery diarrhoea due to pathogens other than rotavirus infection (some results from these subjects have been previously reported) (10) and (ii) to identify the predictors of retinol excretion in children with acute watery diarrhoea.

MATERIALS AND METHODS

The study was conducted at ICDDR,B: Centre for Health and Population Research at Dhaka, Bangladesh, during May-December 1995. Male children, aged five months to five years, hospitalized with history of acute watery diarrhoea, were eligible. The study excluded children with any other complications, including known liver or kidney diseases and congenital illnesses. An informed written consent was obtained from parents before enrolling children in the study. The Ethical Review Committee of ICDDR,B and the University of Alabama at Birmingham approved the study.

After initial enrollment, children were observed in a study ward for about 4-6 hours. Depending on the status of dehydration, the children were rehydrated using either an oral rehydration solution (ORS) or an intravenous polyelectrolyte solution. Stool samples were examined for rotavirus antigen using a rapid latex agglutination test (Slidex Rota kit, Biomerieux, France) (13). Children were enrolled in this study if their stools were negative for rotavirus by this agglutination test.

Stool samples on admission were cultured for Vibrio cholerae, Shigella, and Salmonella using standard methods (14). Stool samples were also confirmed for rotavirus by enzyme-linked immunosorbent assay (ELISA), using the Dakopatts kit (Glostrup, Denmark). Stool microscopy was performed for parasites, ova, and blood cells. After initial rehydration, blood samples were obtained by venipuncture and kept in containers wrapped with aluminum foil to prevent degradation of vitamin A by light. The blood samples were tested for retinol, RBP, transthyretin (TTR) (previously known as pre-albumin), electrolytes, creatinine, glucose, albumin, and phosphate. Urine samples were collected for 24 hours on day 1 and day 3 using single-use, sterile, paediatric urine-collectors (PUC, Kobayashi Shoji K. …

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