URINARY SELENIUM EXCRETION IN INFANCY - COMPARISON BETWEEN TERM AND PRETERM INFANTS

We evaluated the urinary excretion of selenium (Se), an essential comp onent of glutathione peroxidase, in infants aged 1 week and 1, 4, and 7 months and examined the relationship between urinary Se and renal fu nction. Daytime spot urine samples from a total of 80 infants were ana lyzed. The Se concentration in urine was measured by fluorometry, whil e the beta(2)-microglobulin content, an index of renal tubular functio n, was determined by radioimmunoassay. In healthy term infants, the ur inary Se excretion showed a peak level at 1 month of age. In contrast, the urinary Se concentration rapidly decreased in preterm infants fro m 1 week to 7 months postnatally. The level at 1 week in preterm infan ts was significantly higher than that in term infants, although the me an levels at I, 4, and 7 months were lower in preterm infants. The lev el of urinary Se did not correlate significantly with the beta(2)-micr oglobulin concentration, either in term or preterm infants at any age investigated. Our results suggest that the renal excretion of Se proba bly reflects the body stores of Se and is not related directly to the renal function in infants. Urinary Se, a noninvasive marker of the Se status, may be used for diagnosis and follow-up of Se deficiency in in fants.