Author(s): Sara Chandy, Basil Paul Kunnathu
BACKGROUND Evidence of early diabetic nephropathy can be quantified by either urinary Protein Creatinine Ratio (PCR) or 24-hour urinary protein estimation, the latter being the gold standard. Proteinuria is directly linked to diabetic retinopathy and the PCR threshold for onset of diabetic retinopathy needs to be determined. MATERIALS AND METHODS Correlation of spot urine protein creatinine ratio (PCR) with 24-hour urine protein estimation in a sample of patients with type 2 diabetes was first assessed. They were grouped by stage of diabetic retinopathy (DR). Receiver Operating Characteristic (ROC) analysis was used to compute the optimum cut-off values of urinary PCR and 24-hour urine protein to predict DR. Clinical and other biochemical parameters were also correlated with proteinuria. RESULTS Urinary PCR correlated well with 24-hour urine protein values and were excellent at higher ranges of eGFR. All clinical and biochemical parameters correlated well with urine PCR except for duration of diabetes and HbA1c. The cut off value of 24-hour urine protein and urine PCR for predicting the onset of diabetic retinopathy was 1178 mg/24 hrs and 1.67 respectively. Retinopathy worsens significantly with worsening proteinuria with urine PCR values nearly doubling with each stage of retinopathy. CONCLUSION In clinical practice, spot urine PCR needs to be closely monitored from the onset of T2DM for possible early diabetic nephropathy and any value below and near its threshold value necessitates prompt evaluation and intervention for retinopathy. Follow up retinal evaluation is mandated in the face of worsening Urine PCR.