Overestimation of Nuclear Matrix Protein 22 in Concentrated Urine

Objective To confirm the hypothesis that nuclear matrix protein 22 (NMP22) is overestimated in concentrated urine, we compared the NMP22 values measured at different dietary states. Methods We retrospectively reviewed 531 healthy subjects who had had abnormal urinary NMP22 values ≥10 U/mL at the first test and underwent a second NMP22 test within 2 weeks. The first NMP22 test was performed after overnight fasting, and the second was performed with no dietary restrictions. We compared the NMP22 values between the 2 measurements and investigated the relationship between the NMP22 value and urine specific gravity. Results At the second test, 504 subjects (94.9%) had a normal NMP22 value of