Determining the Value of Albumin to Creatinine Ratio in a Single Morning Sample, Compared to the 24-Hour Urinary Albumin Excretion Test, for Determining Micro-Albuminuria in Diabetic Patients

Background: The aim of the study was to compare albumin to creatinine ratio (ACR) in the morning urine sample with the 24-hour urinary albumin excretion in diabetic patients by using facilities available in Iran, also determining correlation between them and day to day variation of ACR. Methods: In this 8-month long cross-sectional study conducted in the year ending on 20 March 2006 in Zanjan, a 24-hour collected urine sample and 2 single morning samples were evaluated for measuring albumin by use of immune-turbidometry in 201 outpatients afflicted with diabetes mellitus type 2. The correlation coefficient of ACR in single samples and 24-hour urinary albumin excretion samples were assessed by use of Pearson correlation statistical test, and the regression analysis and its diagnostic function in diagnosing of micro-albuminuria. Results: Fifty one out of 201 patients (25.40%) had micro-albuminuria and 8 (4%) were afflicted with macro-albuminuria. The correlation coefficient of ACR was maximally 81% (P<0.0001) and the regression equation obtained was, at the best, 24-hour urinary albumin excretion= 8.526 + (the second day ACR * 0.891). The correlation coefficient in micro-albuminuric patients was statistically significant only with respect to the second day ACR (0.50). Using the usual second day ACR cut-off of 30 mg/g, the sensitivity and specificity of 100% and 93.80%, respectively, for patients under 40 years of age (19), 47.90% and 83.30%, respectively, for 40 years, and more, of age (182) were obtained. Conclusion: Until more assessment of other available laboratory kits is made, the morning urine albumin/creatinine ratio test will not be an acceptable alternative for measuring 24-hour urine albumin in diagnosis of micro-albuminuria in diabetic patients in Iran.