Intra-Day Variation of Urinary Nuclear Matrix Protein 22

Abstract

Nuclear Matrix Protein 22 (NMP22), a urinary tumor marker for urothelial cancers, is directly released into the urine from the nucleus after cell death, Accordingly, values of NMP22 do not requlre adjustment using other substances such as urinary creatinine. On the other hand, its values might vary according to urine concentration. This study investigated the intra-day variation in the urinary level of NMP22. NMP22 and urinary creatinine were measured in a 24-hour urine sample and 4 spot urine samples obtained from 20 inpatients (10 with bladder cancer, and 10 with non-urothelial cancer or benign tumors). The spot urine samples were collected at 6 a.m., 10 a.m., 2p.m. and 9 p.m. There were no significant differences in NMP22 values between the 24-hour and spot samples in all patients. Out of 10 bladder cancer patients, 6 had positive 24-hour samples. Among these 6 patients, only 3 had 4 positive spot samples (>12.O U/ml): one had 3 positive samples, and 2 had one positive sample. Among the controls, only one patient with renal cancer had a positive 24-hour sample. Only 3 controls, 2 With prostatic cancer and one with renal cancer, had a single positive spot sample. The highest margin between the maximum and minimum levels in the 4 spot samples was 237.8 U/ml in the bladder cancer patients and 16.6 U/ml in the controIs. When the ratios of NMP22 and urinary creatinine values for the 24-hour to spot samples were calculated in each patient, a significant correlation was observed between the ratios of NMP22 and urinary creatinine (r=0.575, p<0.001). The urinary level of NMP22 shows intra-day variation and might be affected by the extent of the concentration of urine samples. The measurement results must be judged with this in mind, especially when judging the results around the cut-off value.