Usefulness of protein/creatinine ratio in spot urine using test strips

• Published in: Rinsho byori. The Japanese journal of clinical pathology Vol. 53; no. 9; p. 810
• Main Authors: Naka, Chisato, Takahashi, Hakuo, Shiba, Kiyoko, Fujita, Yoshikazu, Fukuta, Isao, Kosaka, Hideko, Sakamoto, Hisashi
• Format: Journal Article
• Language: Japanese
• Published: Japan 01.09.2005
• Subjects: Creatinine - urine; Humans; Proteinuria - urine; Reagent Strips - standards; Sensitivity and Specificity
• ISSN: 0047-1860

The influence of concentration and dilution has been the major issue of urinalysis. This study is to evaluate the usefulness of protein (P)/creatinine (C) ratio (P/C ratio) in spot urine by test strips method. For this purpose, the basic performance of creatinine test strips is evaluated and judging criteria for the urine P/C ratio is defined. Our evaluation revealed that the creatinine test strips were basically not affected by substances which have similar composition to creatinine, such as creatine, but by some medical agents and disinfectant. Its minimum detective sensitivity was 6.0 mg/dl, while that of protein test strips was 1.3 mg/dl. We determined judging criteria for the P/C ratio as follows: Below 80 mg/gCr, Normal; 80 to 500mg/gCr, 1 +; over 500 mg/gCr, 2+. The P/C ratio based on the quantitative and test strips methods provided good consistency of 82.2%. In low-creatinine urine samples (11 to 99mg/dl), 181 of 216 samples (83.8%) were tested negative on single-protein tests; while the P/C ratio provided fewer negative results, 134 of 216(62.0%). Moreover, in high-creatinine urine samples (200 to 600 mg/dl), 70 of 122 samples (57.4%) were tested negative on single protein tests; while the P/C ratio provided negative results in almost all the samples, 120 of 122 (98.4%). These urine samples were mostly collected at a medical examination. The results above showed that the P/C ratio obtained by easy and quick test strip method is equivalent to the quantitative method in performance and useful for spot urine testing.