Establishment of a Method to Detect Microalbuminuria by Measuring the Total Urinary Protein-to-Creatinine Ratio in Diabetic Patients

Abstract

Diabetes and chronic kidney disease (CKD) which are risk facters of cardiovascular disease, are increasing global public health problems. Microalbuminuria is an early sign of progressive cardiovascular and renal disease in individuals with or without diabetes. Screening for microalbuminuria and early treatment are recommended for patients with increased cardiovascular and renal risk factors. However, the procedure used to measure urinary albumin is expensive. Alternatively, the measurement of total urinary protein is simple and inexpensive. Thus, we aimed to establish a method that could predict the presence of microalbuminuria by measuring the total protein-to-creatinine ratio. Spot urine samples were obtained from 150 patients with diabetes mellitus, and the total protein-to-creatinine ratio and the albumin-to-creatinine ratio (ACR) were measured. There was a significant positive correlation between the protein-to-creatinine ratio and the ACR (r = 0.95). The presence of albuminuria (both micro-and macroalbuminuria) could be predicted from the value of the protein-to-creatinine ratio in more than 90% of patients. A receiveroperating characteristic curve analysis revealed that the protein-to-creatinine ratio had a sensitivity and a specificity of 90.8% and 91.9%, respectively, for the detection of albuminuria and a cutoff value of 0.091 g/g creatinine. These results suggest that screening for microalbuminuria can be replaced by the detection of the protein-to-creatinine ratio, which may be cost-effective for patients with cardiovascular risks as well as for the general population.

Modified Cut-Off Value of the Urine Protein-To-Creatinine Ratio Is Helpful for Identifying Patients at High Risk for Chronic Kidney Disease: Validation of the Revised Japanese Guideline

“…However, other studies have examined the relationship between the ACR and PCR (Atkins et al 2003;Methven et al 2010;Smith et al 2012). Our group previously reported that the PCR is highly correlated with the ACR and that an ACR of 30 mg/g creatinine is equivalent to a PCR of approximately 0.08-0.09 g/g creatinine, based on the analyzed datasets (Yamamoto et al 2011(Yamamoto et al , 2014. Fisher et al (2013) reported that the ACR and PCR are relatively similar and that an ACR of 30 mg/g creatinine is equivalent to a PCR of approximately 0.08-0.11 g/g creatinine based on regression and Lowess smooth analyses in a recent large CKD cohort study.…”

“…This study was based on a secondary analysis of our two previous outpatient studies, with 150 diabetic patients included in the first study (2011) (hereafter, Study 1) (Yamamoto et al 2011) and 784 cardiovascular patients included in the second study (2014) (hereafter, Study 2) (Yamamoto et al 2014). The methods and primary results were reported in detail in each article.…”

“…However, this assumption is based on incomplete evidence, and no validation studies are available. The latest studies of the relationship between ACR and PCR have indicated that an ACR of 30 mg/g creatinine is equal to a PCR of slightly lower than 0.15 g/g creatinine (Yamamoto et al 2011(Yamamoto et al , 2014Fisher et al 2013). These results challenge the validity of the PCR-based classification method recommended by the Japanese CKD guideline.…”

Can Urinary Total Protein-to-Creatinine Ratio Determine the Presence of Micro albuminuria in Patients with eGFR> 60 ml/ml/min/m²?

“…The optimal cut-off value for predicting microalbuminuria for TPCR was found to be 119 mg/g creatinine. Various studies have reported positive correlation between TPCR and ACR [13][14][15]. For the first time, the study of Yamamoto et al [15] has shown that TPCR measurement in diabetic patients predisposes to the presence of microalbuminuria.…”

“…The association between proteinuria and albuminuria has been shown in many studies [11][12][13][14][15]. The cutoff value that predicts the micro-albuminuria of TPCR has been determined only in a limited number of studies [14,15].…”