Urinary zinc excretion in infancy.
In view of the conflicting data on urinary Zn excretion in infancy we investigated the possible influence of contamination, collecting methods, nutrition (human milk versus formula) and longitudinal changes during the first 16 weeks of life. Methodical investigation showed that special attention is necessary to avoid contamination due to the use of Zn-containing baby creams in the genital region. The sampling device for collection should include the smallest area of skin possible and the use of Zn-containing baby creams has to be avoided both during the collection and at least 24 hours prior to urine collection. Previous fractional urine sampling of the collecting method to be evaluated proves that erroneously high values are not obtained at the beginning of collection. Midstream urinary samples reduce the possibility of contamination. Increased urinary excretion was shown in pre-term infants under theophylline or coffeine medication. The median daily urinary Zn excretion in healthy breast-fed term infants declined significantly from 0.063 (0.027-0.111) mg per kg body weight at the age of 2 weeks to 0.018 (0.004-0.059) mg per kg body weight at the age of 16 weeks. Comparable values for formula-fed term infants were 0.029 (0.025-0.063) mg per kg body weight initially and 0.025 (0.007-0.059) mg per kg body weight at the end of the study. These values can be used as reference values for the urinary Zn excretion of healthy infants.
Sievers
E
E
Department of Pediatrics, University of Kiel, Fed. Rep. of Germany.
Oldigs
H D
HD
Dörner
K
K
Schaub
J
J
D000375:Aging / Q000378:metabolism; D002110:Caffeine / Q000494:pharmacology; D005333:Fetus / Q000378:metabolism; D006801:Humans; D007225:Infant Food; D007231:Infant, Newborn; D008297:Male; D008895:Milk, Human / Q000378:metabolism; D015203:Reproducibility of Results; D013048:Specimen Handling; D013054:Spectrophotometry, Atomic; D013806:Theophylline / Q000494:pharmacology; D015032:Zinc / Q000008:administration & dosage / Q000652:urine*
D002110:Caffeine; D013806:Theophylline; D015032:Zinc