To determine whether measurement of the protein-to-creatinine ratio in random urine samples correlate with 24-h urine protein in non diabetic nephropathy patients.
This prospective, observational analytic study included 300 subjects with kidney disease other than diabetic nephropathy. Urinary protein was estimated using immunoturbidimetric method and Urinary creatinine was estimated using modified Jaffe's method on Synchron CX clinical chemistry analyzer. Protein creatinine ratio (PCR) and 24 h urine protein and 24 h urine creatinine were estimated and correlation analysis was performed. SPSS version 13 (IBM Corp) and Microsoft excel (Microsoft Inc.) were used for statistical calculation. Pearson's product moment correlation analysis was performed to assess for correlation between parameters.
Mean age of study subjects was found to be 50.44 years (S.D. = 17.62). Study population included 103 females and 197 males. Pearson product-moment correlation coefficient between PCR and 24 hr urinary protein was found to be r = 0.54 (r2 = 0.29) indicating significant moderate positive correlation (p < 0.001). In subjects with associated with hypertension (n = 231) the correlation coefficient was found to be slightly lower r = 0.50 (r2 = 0.25) but yet indication significant moderate positive correlation (p < 0.001). Significantly strong positive correlation between two parameters was noted in CKD other than those associated with hypertension (r = 0.68, r2 = 0.46, p < 0.001). The correlation was found to be mildly positive when PCR < 0.2 (cut-off for normal PCR) (r = 0.38, r2 = 0.152, p < 0.004) and moderately positive when PCR ≥ 0.2 (r = 0.51, r2 = 0.26, p < 0.001).The correlation is better observed in older aged persons(>70yrs),non vegeterians,male sex,24hrs urine protein >300 mg range and PCR > 0.2.
Protein creatinine ratio in spot urine sample can be used in place of 24 hour urine protein in assessment of CKD status. The replacement is more reliable in CKD subjects associated with non hypertensive causes. But the correlation is not uniform and varies in different patient subsets.
Department of Internal Medicine, Asian Institute Of Medical Sciences, Faridabad, Haryana 121001, India