title: Circadian rhythms of urine osmolality and renal excretion rates of solutes influencing water metabolism in 21 healthy children.
abstract: Circadian rhythms of urine excretion, urine osmolality and renal excretion rates of sodium, chloride, potassium, creatinine and urea were studied for 3 days at home in 21 healthy children aged 6-11 years. Urine production as well as renal excretion rates of all solutes studied increased significantly during daytime and had minimum values at night. The peak of potassium and chloride excretion rates occurred earlier in the day than that of sodium. Considering all children together, no circadian rhythm was seen for urine osmolality. However, 9 children had evident but individually different rhythms of urine osmolality, changes which did not seem to correspond to the daily distribution of water intake. Circadian rhythmicity of urine osmolality and renal excretion rates of the main solutes should be considered in diagnostic and therapeutic procedures concerning fluid and electrolyte metabolism.
authors.affiliation: Research Institute of Child Nutrition, Dortmund, FRG.
authors.forename: A
authors.initials: A
authors.lastname: Ballauff
authors.forename: W
authors.initials: W
authors.lastname: Rascher
authors.forename: H G
authors.initials: HG
authors.lastname: Tölle
authors.forename: T
authors.initials: T
authors.lastname: Wember
authors.forename: F
authors.initials: F
authors.lastname: Manz
mesh_terms: D001834:Body Water / Q000378:metabolism*; D002648:Child; D002712:Chlorides / Q000652:urine; D002940:Circadian Rhythm / Q000502:physiology*; D003404:Creatinine / Q000652:urine; D005260:Female; D006801:Humans; D007668:Kidney / Q000378:metabolism*; D008297:Male; D009994:Osmolar Concentration; D011188:Potassium / Q000652:urine; D012016:Reference Values; D012964:Sodium / Q000652:urine; D014508:Urea / Q000652:urine; D014556:Urine / Q000737:chemistry*
chemical_list: D002712:Chlorides; D014508:Urea; D012964:Sodium; D003404:Creatinine; D011188:Potassium