Prediction of microalbuminuria by analysing total urine protein-to-creatinine ratio in diabetic nephropathy patients in rural Sri Lanka

Introduction: Chronic kidney disease (CKD) is a major complication of diabetes mellitus and it contributes to increased hospital mortality and morbidity. Microalbumin test is used to identify the first sign of deteriorating kidney function but it is an expensive test. Alternatively, measurement of urine total protein-to-creatinine ratio (TPCR) is a simple and inexpensive method.

Objective: To find whether the urine TPCR can predict the presence of microalbuminuria in patients with diabetic nephropathy.

Method: A cross sectional study was performed on 216 patients with diabetes mellitus at General Hospital, Ampara over a period of 4 weeks. Urine albumin, urine creatinine and urine total protein were analysed on first voided urine samples and urine albumin to creatinine ratio (ACR) and total-protein-to-creatinine ratio were calculated. Regression analysis and Spearman’s rank correlation were used to study the linear relationship between two variables.

Results: Among 216 patients, 56 (26.1%) were males and 160 (73.9%) were females. The mean urine total-protein-to-creatinine ratio was 89.3 ± 231.6 mg/g and albumin to creatinine ratio was 43.1±76.3 mg/g. Sixty four (29%) patients were newly detected as having microalbuminuria (n=61; 28%,) or macroalbuminuria (n=3; 1%,). There was a significant correlation between urine total-protein-to-creatinine ratio and urine albumin to creatinine ratio (R2 = 0.824, ACR = [TPCR + 18.421]/ 2.5026) in the total sample (p < 0.001). The total-protein-to-creatinine ratio showed a significant correlation with urine albumin to creatinine ratio in the range of microalbuminuria (30-300 mg/g creatinine) (R2 = 0.798; p < 0.001). The regression equation was ACR = [TPCR – 5.0491]/1.2633.

Conclusion: The urine total-protein-to-creatinine ratio showed a positive significant correlation with urine albumin to creatinine ratio, which is clinically important to identify early stage of diabetic nephropathy. This can be used in rural areas as it is inexpensive.