Is there a physiological variability for albumin excretion rate? Study in patients with diabetes type1 and non-diabetic individuals

Background: To determine the intraindividual coefficient of variation (CY) of albumin excretion rate (AER). Method: We studied 76 patients with type 1 diabetes and 66 non-diabetic subjects (ND) under routine clinical conditio ns providing three timed overnight urine samples for urinary albumin determ ination by radioimmunoassay. Results: Patients and ND had similar CV, of AE R (50.7 +/- 33.3 vs. 58.1 +/- 33.2% P=0.12). Intermittent microalbuminuric subjects tone out of 3 AER >20 mug/min) had higher CV of ER than normoalbum inuric and persistent microalbuminuric patients. [84.9 (37.1-145. 3) vs. 39 .8 (4.9-124.8) vs. 34.6 (12.1-116.5)% P=0.00071 without difference between the two latter groups. In patients, the independent factor associated with the CV, of AER in multiple regression analysis was age (r(2)=0.08: P=0.01). Sensitivity (95% CL) and specificity of first AER for diagnosing microalbu minuria was 85.7% (42.0-99.2) and 91.3% (81.4-96.4). Conclusions: Our findi ngs suggest the variability of AER was physiological. unrelated to diabetic condition. First AER could be used for screening of microalbuminuria follo wed by a second one when the patient has AER >20 mug/min in the first. This would result in low cost for screening and diagnosis of microalbuminuria t hat is nor always feasible in routine clinical practice in developing count ries using three urine samples. (C) 2001 Elsevier Science B.V. All rights r eserved.