title: Normal and abnormal day-to-day variability of urinary albumin excretion in control and diabetic subjects.
abstract: Urinary albumin excretion (UAE) is very variable from day to day. This variability, more or less potent, might by itself have a patho-physiological significance. We analyzed day-to-day UAE in 207 elderly (60-75 years) inpatients (134 with and 73 without diabetes mellitus) attending the department of internal medicine of the Angers University hospital. Twenty-four-hour urine was collected 3 times during a 5-10 day hospitalization period. One-hundred-fifty-one patients (73%) displayed normoalbuminuria (UAE<30 mg/24 h in 2 or 3 measures) while 56 patients (27%) had microalbuminuria (UAE within 30-300 mg/24 h in 2 or 3 measures). As the raw data of UAE was not normally distributed, we transformed UAE into the variable z=log (log (k + UAE)) where k is an integer and looked for a k value for which z might be normally distributed. We found that z was actually normally distributed for k=2. Mean value and coefficient of variation of z in the 3 measurements were used to define the level and the temporal intra-individual variability of UAE. Expressed in term of z, the day-to-day intra-individual variability of UAE showed a potent change (from large variability to small variability) at the particular level z=1.25, corresponding to UAE=30.8 mg/24 h. This value is precisely the level currently used to define microalbuminuria in diabetic subjects. It is remarkable that the day-to-day variability of UAE collapses when UAE crosses the level which has been used to define microalbuminuria.
authors.affiliation: Equipe Biostat-Biomath, INSERM U444, Université Paris VII-Denis Diderot, Paris, France. chau@urbb.jussieu.fr
authors.forename: N P
authors.initials: NP
authors.lastname: Chau
authors.forename: B
authors.initials: B
authors.lastname: Bouhanick
authors.forename: D
authors.initials: D
authors.lastname: Mestivier
authors.forename: M
authors.initials: M
authors.lastname: Taki
authors.forename: M
authors.initials: M
authors.lastname: Marre
mesh_terms: D000368:Aged; D000419:Albuminuria; D015992:Body Mass Index; D002940:Circadian Rhythm; D003404:Creatinine / Q000097:blood; D003920:Diabetes Mellitus / Q000097:blood / Q000503:physiopathology / Q000652:urine*; D003971:Diastole; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011934:Reagent Strips; D012016:Reference Values; D012044:Regression Analysis; D013599:Systole; D013997:Time Factors
chemical_list: D003404:Creatinine; D006442:Glycated Hemoglobin; D011934:Reagent Strips