title: Sex difference of urinary osmolality in German children.
abstract: OBJECTIVE
  Origin of sex difference in urinary osmolality.
  
  
  METHODS
  In 495 healthy children aged 4.0-14.9 years participating in the DONALD (Dortmund Nutritional and Anthropometric Longitudinally Designed) study (247 boys, 248 girls), the water intake recorded in 24-hour weighed dietary records along with urinary volume, osmolality and free water reserve in 24-hour urine samples from the same day as the dietary record were determined.
  
  
  RESULTS
  Boys showed a significantly higher energy intake, total water intake, urinary osmolality and osmolar load than girls but no increase in urinary volume. When referred to energy intake, mean urinary volume and mean free water reserve were significantly higher in girls than boys. Girls could have a preference for food with a higher water density and lower non-renal water losses.
  
  
  CONCLUSIONS
  German girls of the DONALD study displayed a lower urinary osmolality than German boys due to a relatively higher urinary volume. The sex difference could be caused by a higher water density of the ingested food (ml/kcal) and a lower insensible water loss (ml/kcal) in girls than boys.
authors.affiliation: Research Institute of Child Nutrition, Dortmund, Germany.
authors.forename: Arno
authors.initials: A
authors.lastname: Ebner
authors.forename: Friedrich
authors.initials: F
authors.lastname: Manz
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004326:Drinking / Q000502:physiology; D002149:Energy Intake / Q000502:physiology; D005260:Female; D005858:Germany; D006801:Humans; D008297:Male; D009994:Osmolar Concentration; D012737:Sex Factors; D013997:Time Factors; D014556:Urine / Q000502:physiology*; D014563:Urodynamics