title: The influence of urinary flow rate in children on excretion of markers used for assessment of renal damage: albumin, gamma-glutamyl transpeptidase, N-acetyl-beta-D -glucosaminidase, and alpha1-microglobulin.
abstract: The aim of the present study was to examine the influence of urinary flow rate on markers of renal function in children. A sub-study of the New England Children's Amalgam Trial collected 82 pairs of urine samples from children aged 10-16 years: a timed overnight collection and a spot daytime sample collected the following day. These samples were analyzed for albumin, gamma-glutamyl transpeptidase (gamma-GT), N-acetyl-beta-D-glucosaminidase (NAG), alpha1-microglobulin (A1M), and creatinine concentration. Regression analysis was used to model the effect of urinary flow rate in the timed overnight samples. A paired t-test compared concentrations and creatinine-corrected renal markers between overnight and daytime samples. Albumin, gamma-GT, NAG, and A1M excretion rates increased significantly with urinary flow rate. Their corresponding creatinine-corrected markers did not vary significantly with urinary flow rate, but the creatinine-corrected excretions of albumin, gamma-GT, and NAG were significantly higher in daytime samples than in overnight samples, with the same (non-significant) trend for A1M. The influence of urinary flow rate on creatinine-corrected markers of renal function was markedly less than its influence on excretion rates. Therefore, the use of creatinine-corrected markers seems to be a good choice in practice, with the caveat that daytime and overnight samples are not comparable.
authors: New England Research Institutes, 9 Galen St., Watertown, MA 02472, USA. ftrachtenberg@neriscience.com
authors: Felicia
authors: F
authors: Trachtenberg
authors: Lars
authors: L
authors: Barregard
authors: Sonja
authors: S
authors: McKinlay
mesh_terms: D000118:Acetylglucosaminidase / Q000652:urine; D000293:Adolescent; D000419:Albuminuria / Q000652:urine; D000510:Alpha-Globulins / Q000652:urine; D015415:Biomarkers / Q000652:urine; D002648:Child; D002940:Circadian Rhythm; D003404:Creatinine / Q000652:urine; D005260:Female; D006801:Humans; D007674:Kidney Diseases / Q000503:physiopathology* / Q000652:urine*; D008297:Male; D014563:Urodynamics; D005723:gamma-Glutamyltransferase / Q000652:urine
chemical_list: D000510:Alpha-Globulins; D015415:Biomarkers; C016001:alpha-1-microglobulin; D003404:Creatinine; D005723:gamma-Glutamyltransferase; D000118:Acetylglucosaminidase
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