title: Diurnal variation in urinary protein excretion in diabetic nephropathy.
abstract: We examined the diurnal variation in urinary excretion rate of albumin, IgG and beta 2-Microglobulin (beta 2-M) in healthy volunteers (n = 24), and in patients with type I diabetes mellitus having normal albumin excretion rate (less than 20 micrograms/min; n = 16), incipient diabetic nephropathy (albumin excretion rate 20-200 micrograms/min; n = 12) and clinical diabetic nephropathy (albumin excretion rate greater than 200 micrograms/min; n = 12). Diurnal variation was defined as [(overnight minus daytime): daytime excretion rate] times 100%. Median diurnal variation in albumin excretion rate in the various groups varied from -32 to -57%, and in IgG excretion rate from -42 to -65%, being not significantly different between the proteins or between the groups. Diurnal variation in beta 2-M excretion rate was similar in healthy volunteers and in patients with normal albumin excretion rate or incipient diabetic nephropathy (median -36 to -43%), but significantly reduced in patients with clinical diabetic nephropathy (median 0%; P less than 0.005), nine of whom had elevated beta 2-M excretion rates, suggesting tubular dysfunction. Except for beta 2-M excretion rate in patients with clinical diabetic nephropathy, the diurnal variations in albumin excretion rate, IgG excretion rate and beta 2-M excretion rate were larger than the diurnal variation in creatinine excretion rate (median -7 to -11%, P less than 0.005). Diurnal variations in albumin excretion rate and IgG excretion rate were highly correlated (r = 0.89, P less than 0.00001). These data suggest that similar mechanisms may account for diurnal variations in albumin excretion rate and IgG excretion rate.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Internal Medicine, Bergweg Municipal Hospital, Rotterdam, The Netherlands.
authors.forename: C D
authors.initials: CD
authors.lastname: Stehouwer
authors.forename: H R
authors.initials: HR
authors.lastname: Fischer
authors.forename: W H
authors.initials: WH
authors.lastname: Hackeng
authors.forename: G J
authors.initials: GJ
authors.lastname: den Ottolander
authors.forename: A J
authors.initials: AJ
authors.lastname: Donker
mesh_terms: D000328:Adult; D000419:Albuminuria / Q000150:complications / Q000652:urine; D002940:Circadian Rhythm; D003404:Creatinine / Q000652:urine; D003922:Diabetes Mellitus, Type 1 / Q000150:complications / Q000652:urine; D003928:Diabetic Nephropathies / Q000150:complications / Q000652:urine*; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000652:urine; D008297:Male; D011507:Proteinuria / Q000150:complications / Q000652:urine*; D001613:beta 2-Microglobulin / Q000652:urine
chemical_list: D007074:Immunoglobulin G; D001613:beta 2-Microglobulin; D003404:Creatinine