Analysis of albumin-to-creatinine ratio on automated analysers using a microsampling card (Capitainer DIP70 card) for the collection of urine.

OBJECTIVES

Albuminuria is a key biomarker of kidney damage, yet preanalytical challenges with conventional liquid urine testing, limiting its utility for decentralized and large-scale screening. This study evaluated the analytical performance of a novel dried urine spot (DUS) device, for measuring urinary albumin-to-creatinine ratio and assessed its agreement with standard liquid urine analysis.

METHODS

One hundred routine urine samples were analysed both as liquid and dried specimens prepared with the DUS device. After drying, discs were eluted and tested on three clinical chemistry platforms (Roche Cobas Pro, Abbott Alinity, Siemens Atellica). Albumin-to-creatinine ratio (ACR) was calculated. Statistical analyses included duplicate precision (coefficient of variation), linear regression, and Bland-Altman comparison. A stability study was conducted under multiple temperature conditions.

RESULTS

ACR values obtained from DUS samples showed strong concordance with liquid urine results (Roche Cobas Pro: y=1.024×-1.427; R2=0.997; Siemens Atellica y=0.983 + 0.336; R2=0.958 and Abbott Alinity: y=1.062×-0.360; R2=0.991). Across ACR intervals (<3 mg/mmol, 3-30 mg/mmol >30 mg/mmol), Cobas demonstrated small positive median differences (0.46, 0.25, 0.62 mg/mmol), Alinity showed variable differences (-0.87, 0.27, -0.24 mg/mmol), and Atellica yielded consistently positive, slightly larger differences (0.47, 2.42, 1.33 mg/mmol).

CONCLUSIONS

The DUS device provides a robust and reproducible alternative to liquid urine sampling for albumin and creatinine measurement. Its ability to enable decentralized, ambient-temperature collection with strong analytical agreement supports its application in population screening, remote monitoring, and kidney disease research.