Urinary retinol excretion and kidney function in children with shigellosis.
BACKGROUND
Acute infections, including diarrhea, are associated with an increased risk of vitamin A deficiency. Urinary retinol excretion during such infections may contribute to this risk. The mechanism accounting for urinary retinol loss has not been clearly defined.


OBJECTIVE
This study attempted to determine whether urinary retinol loss in children with acute infection is associated with impaired kidney function, particularly impaired tubular protein reabsorption.


METHODS
Urinary retinol excretion and kidney function were examined in 66 hospitalized children 5 mo to 5 y of age with acute Shigella dysentery.


RESULTS
Urinary retinol loss occurred in 59% of children and was substantial (>0.1 micromol/d) in 8% of them. Children with more severe disease excreted higher concentrations of urinary retinol; those with a body temperature > or =40 degrees C excreted a mean of 0.10 +/- 0.18 micromol/d compared with 0.005 +/- 0.008 micromol/d for other children (P < 0.0001). Children with more severe disease also had impaired tubular reabsorption of low-molecular-weight proteins beta2-microglobulin and retinol binding protein (RBP)], although other measures of tubular and glomerular function were not similarly impaired. In multiple regression analysis, severity of disease indicators were the best predictors of tubular reabsorption of beta2-microglobulin (R2 = 0.53) whereas tubular reabsorption of beta2-microglobulin and RBP were found to be the best predictors of urinary retinol loss (R2 = 0.69).


CONCLUSIONS
A significant amount of retinol was excreted in the urine in children with shigellosis: 8% excreted >0.10 micromol/d (15% of the daily metabolic requirement). Impaired tubular reabsorption of low-molecular-weight proteins, such as RBP transporting retinol, appeared to be the cause of this urinary retinol loss.
Mitra
A K
AK
Department of International Health, University of Alabama at Birmingham, USA.
Alvarez
J O
JO
Guay-Woodford
L
L
Fuchs
G J
GJ
Wahed
M A
MA
Stephensen
C B
CB
D002097:C-Reactive Protein / Q000378:metabolism; D002675:Child, Preschool; D015331:Cohort Studies; D004405:Dysentery, Bacillary / Q000097:blood / Q000378:metabolism / Q000652:urine*; D005919:Glomerular Filtration Rate; D006801:Humans; D007223:Infant; D007668:Kidney / Q000378:metabolism* / Q000502:physiology; D008297:Male; D009748:Nutrition Disorders / Q000378:metabolism / Q000652:urine; D009752:Nutritional Status; D009961:Orosomucoid / Q000378:metabolism; D012044:Regression Analysis; D012177:Retinol-Binding Proteins / Q000378:metabolism; D012720:Severity of Illness Index; D012760:Shigella / Q000302:isolation & purification; D014801:Vitamin A / Q000097:blood / Q000652:urine*
D009961:Orosomucoid; D012177:Retinol-Binding Proteins; D014801:Vitamin A; D002097:C-Reactive Protein