Observational Study
Copyright ©The Author(s) 2023. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Nephrol. Dec 25, 2023; 12(5): 159-167
Published online Dec 25, 2023. doi: 10.5527/wjn.v12.i5.159
The correlation of spot urinary protein-to-creatinine ratio with 24-h urinary protein excretion in various glomerulopathies
Amber Raza, Syed Haider Nawaz, Rahma Rashid, Ejaz Ahmed, Muhammed Mubarak
Amber Raza, Ejaz Ahmed, Department of Nephrology, Sindh Institute of Urology and Transplantation, Sindh, Karachi 74200, Pakistan
Syed Haider Nawaz, Rahma Rashid, Muhammed Mubarak, Department of Pathology, Sindh Institute of Urology and Transplantation, Sindh, Karachi 74200, Pakistan
Author contributions: Raza A and Ahmed E contributed equally to this work; Raza A, Nawaz SH, Rashid R, Ahmed E, and Mubarak M designed the research study; Raza A, Nawaz SH and Rashid R performed the research; Raza A, Ahmed E, and Mubarak M analyzed the data and wrote the manuscript; All authors have read and approved the final manuscript.
Institutional review board statement: The study was reviewed and approved by the Sindh Institute of Urology and Transplantation (Pakistan).
Informed consent statement: All study participants, or their legal guardian, provided informed written consent prior to study enrollment.
Conflict-of-interest statement: There are no conflicts of interest to report.
Data sharing statement: The dataset and related documents are available from the corresponding author at [dramber88@gmail.com]. Consent was not obtained but the presented data are anonymized and risk of identification is low.
STROBE statement: The authors have read the STROBE Statement-checklist of items, and the manuscript was prepared and revised according to the STROBE Statement-checklist of items.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Muhammed Mubarak, MD, Professor, Department of Pathology, Sindh Institute of Urology and Transplantation, Chand Bibi Road, DFMC, Sindh, Karachi 74200, Pakistan. drmubaraksiut@yahoo.com
Received: August 5, 2023
Peer-review started: August 5, 2023
First decision: September 19, 2023
Revised: September 21, 2023
Accepted: October 23, 2023
Article in press: October 23, 2023
Published online: December 25, 2023
Processing time: 138 Days and 22.3 Hours
ARTICLE HIGHLIGHTS
Research background

There are a number of methods by which the quantification of protein excretion in urine is done to inform clinical decisions. Among these, the estimation of protein excretion in the 24-h urinary sample is the traditional and gold standard method. However, it is cumbersome, time-consuming, and prone to errors. The alternative method of measuring urine protein-to-creatinine ratio (uPCR) is used widely in clinical practice as it is quick, patient-friendly, and reliable. The available data on the correlation between the above two methods is controversial.

Research motivation

We also heavily rely on uPCR for our routine patient care. However, we do not know how it correlates with 24-h urinary protein excretion. This motivated us to determine the correlation and degree of agreement between the two tests, so that we should use uPCR results accordingly.

Research objectives

The objectives of this study were to determine the correlation of spot uPCR with 24-h urinary protein excretion test and in particular, the degree of agreement between the two tests, in patients suffering from various forms of glomerulopathies so that we may use this test with caution in future.

Research methods

This was a cross-sectional, observational study conducted on all newly presenting adult patients (age: 18 to 60 years) with proteinuria who were being investigated for suspected glomerulonephritis (GN). All patients were counseled regarding 24-h urine collection. A spot urine sample was collected the next day at the time of submission of a 24-h urine sample for measuring uPCR along with a blood sample. SPSS version 20.0 was used for statistical analysis.

Research results

A total of 157 patients with a mean age of 30.45 ± 12.11 years were included. There were 94 (59.8%) males and 63 (40.2%) females. The mean 24-h urinary protein excretion was 3192.78 ± 1959.79 mg and the mean spot uPCR was 3.16 ± 1.52 in all patients. A significant but poor correlation was observed between spot uPCR and 24-h urinary protein excretion (r = 0.342, P = 0.01) among all patients. On subgroup analysis, a slightly better correlation was found in patients older than 47 years (r = 0.78), and those with body mass index > 25 kg/m2 (r = 0.45). Bland and Altman's plot analysis of the two tests also showed a wide range of the limits of agreement between the two methods.

Research conclusions

The results from this study show a significant, positive but poor correlation between spot uPCR and 24-h urinary protein estimation in various types of glomerular diseases. The agreement between the two methods was also poor. Hence, there is a need for careful interpretation of the ratio in an unselected group of patients with glomerular diseases.

Research perspectives

There is a need to conduct a well-planned, international, multi-center study to resolve the controversy of correlation and agreement between the two most widely used methods of proteinuria estimation in clinical practice.