title: Accuracy of spot urine protein creatinine ratio in measuring proteinuria in chronic kidney disease stage 3 and 4.
abstract: We studied the accuracy of spot urine protein creatinine ratio (SpUr-PCR) to assess 24 h urine protein excretion (24 h-UP) in patients with chronic kidney disease (CKD). A total of 100 proteinuric CKD patients of stages 3 and 4 were studied. 24 h urine was collected to measure 24 h-UP and creatinine. A random day time urine sample was analyzed to measure the PCR. A formula to estimate 24 h creatinine excretion was derived from linear regression analysis and a correction factor was introduced to assess whether this improves the accuracy of the SpUr PCR in predicting 24 h-UP. Accuracy of the SpUr-PCR was assessed by Pearson's correlation, regression analysis, and Bland Altman analysis. Mean age was 51.85 ± 12 years and 81% of the patients were male. SpUr-PCR predicted 24 h-UP with good accuracy (r = 0.86 on a data transformed to a logarithmic scale, P < 0.001) and there was a good agreement between these two measures of proteinuria. However, SpUr-PCR was inaccurate in the subgroup with nephrotic range proteinuria (r = 0.35, P = 0.062), but when a correction factor for 24-h urine creatinine (24 h-UCr) was introduced, the accuracy of SpUr-PCR improved significantly in this group (r = 0.45, P = 0.013). Introduction of the correction factor improved the degree of agreement between these two measures in women, but not the correlation. Overall, SpUr-PCR accurately predicted 24 h-UP. Adding a correction factor for 24 h-UCr improved correlation in the subgroup of patients with the nephrotic range proteinuria and the degree of agreement in female patients, and hence may be used in expressing proteinuria measured by SpUr-PCR to improve its accuracy in them.
authors: Department of Nephrology, Apollo Hospitals, Chennai, Tamil Nadu, India.
authors: R
authors: R
authors: Nayak
authors: R A
authors: RA
authors: Annigeri
authors: V
authors: V
authors: Vadamalai
authors: R
authors: R
authors: Seshadri
authors: S
authors: S
authors: Balasubramanian
authors: B S
authors: BS
authors: Rao
authors: P C
authors: PC
authors: Kowdle
authors: M K
authors: MK
authors: Mani
keywords: Chronic kidney disease; creatinine excretion; proteinuria; urine protein creatinine ratio