Stability Study of Urine Creatinine Levels in Filter Paper Based Method Transport Medium

Abstract

Kidney disease is a major health problem worldwide, and creatinine is one of its markers for diagnosis. Alternative methods for the measurement of creatinine have been developed, including urine dried on filter papers. Studies proved its accuracy and reliability in comparison with conventional methods involving liquid urine. The researchers aimed to study the stability of human urine creatinine stored in various containers under different temperatures and durations. Urine samples from three (3) participants were subjected to eight (8) combinations of duration, temperature, and container, then triplicated to a total of 72 dried urine samples (DUS). Creatinine was measured using elution and reagent strip analysis. Findings showed that any combination of the physical factors could be used to store and transport DUS. There were no significant differences in the creatinine between one month and one week durations [t (70) = -0.801 (p > 0.05)], 25℃ and 4℃ [t (70) = 1.209 (p > 0.05)], and ziplock and microwavable plastic containers [t (7) = 1.209 (p > 0.05)]. The combination of one-week duration under 4℃ in microwavable plastic containers was the most stable, having the lowest mean difference (0.0 mg/dL). Storage of one month under 4°C in ziplocks showed the largest mean difference of 22.22 mg/dL, representing the least stable combination. The addition of physical variables, procurement of DUS from a broader range of participants with normal and impaired kidney functions, and usage of quantitative creatinine assay to eliminate subjective biases and increase the specificity of the method are recommended.