Semi-quantitative urine test strips stumble on creatinine, study finds

A diagnostic accuracy study of 400 spot urine specimens has found that a semi-quantitative point-of-care strip for measuring the urine albumin-to-creatinine ratio (UACR) performs well for albumin but poorly for creatinine, and that this creatinine weakness is the main analytical driver of misclassification of albuminuria categories. The study evaluated the Dirui H13-Cr semi-quantitative UACR strip against quantitative immunoturbidimetric measurement performed on a Roche Cobas c503 analyzer.

Albuminuria is a key biomarker for chronic kidney disease and cardiovascular risk, and point-of-care UACR testing has been proposed as a way to improve access to chronic kidney disease screening. However, the researchers note that limited evidence has been available on how the individual albumin and creatinine components of semi-quantitative UACR strip tests agree with quantitative laboratory measurements, which is the gap their study was designed to address.

Agreement between the strip-based and quantitative measurements was substantial for urinary albumin, with a Cohen’s kappa coefficient of 0.691 (95% CI, 0.632–0.751). Agreement for urinary creatinine was considerably lower, at kappa 0.377 (95% CI, 0.331–0.423). Despite this disparity between the two components, classification of UACR itself still demonstrated substantial agreement, at kappa 0.627 (95% CI, 0.541–0.714).

The authors conclude from these findings that semi-quantitative creatinine estimation is the primary analytical determinant of UACR misclassification. Because the UACR is a ratio of albumin to creatinine, error in the creatinine component propagates directly into the ratio, and the pattern observed in this study points to the creatinine side of the measurement as the weaker link.

For the detection of abnormal albuminuria, defined as a UACR of 30 mg/g or higher, the strip achieved a sensitivity of 83.66% and a specificity of 83.22%. The positive predictive value was 89.96% and the negative predictive value was 73.91%.

Category-specific analysis according to the KDIGO A1, A2 and A3 albuminuria categories revealed a systematic pattern in the errors. Of 177 specimens classified as A2 by quantitative measurement, 131 (74.0%) were classified as A2 by the strip. More strikingly, of 80 specimens classified as A3, 64 (80.0%) were classified by the strip as A2 rather than A3, indicating that the strip tended to shift the most elevated specimens into the intermediate category.

The work was conducted by researchers at Chiang Mai University Faculty of Associated Medical Sciences in Chiang Mai, Thailand, and was published in Frontiers in Medical Technology.

Overall, the authors conclude that the Dirui H13-Cr strip demonstrated acceptable performance for albuminuria screening, while semi-quantitative urinary creatinine estimation represented an important analytical limitation affecting UACR classification accuracy. They suggest that future development of strip-based UACR technologies should prioritize improved creatinine measurement in order to enhance diagnostic performance.

The findings are relevant to laboratories and screening programs considering semi-quantitative point-of-care UACR testing, since they quantify both the strengths of the albumin component and the specific weakness of the creatinine component in a head-to-head comparison with a quantitative immunoturbidimetric reference method. As with any diagnostic accuracy study of a fixed set of specimens, the reported performance figures apply to the tested strip and comparator in this evaluation, and the authors frame their conclusion as a direction for future strip development rather than a judgment against point-of-care UACR screening itself.

Subject of Research: Diagnostic accuracy of a semi-quantitative urine albumin-to-creatinine ratio strip test compared with laboratory measurement

Article Title: Urinary creatinine estimation as an important analytical limitation of semi-quantitative albumin-to-creatinine ratio strip testing: a diagnostic accuracy study

Article References: Bunpo, P., Nanthawong, P., Chomphusri, C., Ratchawat, W., Kittikunnathum, S., Tanintheerakul, C., & Peerakam, R. (2026). Urinary creatinine estimation as an important analytical limitation of semi-quantitative albumin-to-creatinine ratio strip testing: a diagnostic accuracy study. Frontiers in Medical Technology, 8, Article 1913468. https://doi.org/10.3389/fmedt.2026.1913468

Image Credits: AI Generated

DOI: 10.3389/fmedt.2026.1913468

Keywords: albuminuria, urine albumin-to-creatinine ratio, point-of-care testing, diagnostic accuracy, urinary creatinine, chronic kidney disease, immunoturbidimetric assay, Cohen's kappa, KDIGO categories, screening, Urinary, creatinine