[Normal and abnormal daily variability of urinary excretion of albumin].
Urinary albumin excretion (UAE) is very variable from day to day. 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. We found that z has a gaussian distribution 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, which is precisely the level currently used to define microalbuminuria in diabetic subjects.
Chau
N P
NP
Biostat-Biomath, INSERM U444, université Paris VII-Denis-Diderot.
Bouhanick
B
B
Mestivier
D
D
Taki
M
M
Marre
M
M
D000368:Aged; D000419:Albuminuria / Q000652:urine*; D001794:Blood Pressure / Q000502:physiology; D016009:Chi-Square Distribution; D002851:Chromatography, High Pressure Liquid; D002940:Circadian Rhythm / Q000502:physiology*; D003404:Creatinine / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000652:urine; D005260:Female; D005500:Follow-Up Studies; D006442:Glycated Hemoglobin / Q000032:analysis; D006760:Hospitalization; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009391:Nephelometry and Turbidimetry; D016011:Normal Distribution
D003404:Creatinine; D006442:Glycated Hemoglobin