Urinary Immunoassay Useful for Urothelial Carcinoma Diagnosis

Nuclear matrix protein 22 (NMP22) is a specific protein found in the cell nucleus. Malignant neoplasia elevates intracellular NMP22 at least 25 fold, resulting in shedding of the protein into the urine. An enzyme linked immunoassay (ELISA) kit can detect NMP22 in voided urine.

The NMP22 BladderChek Test was used in conjunction with urinary cytology, to evaluate 53 clinically suspected patients with low-grade urothelial carcinoma (25), high-grade urothelial carcinoma (13), and inflammatory lesions (15). This study was conducted in University College of Medical Sciences, (Delhi, India), from January 2004 to May 2008. The age of the patients ranged from 33 to 83 years (mean age 59 years). There were 5 women and 48 men. All patients had history of continuous or intermittent hematuria. A total of 14 patients had previous history of recurrent urinary tract infection.

NMP22 Bladder check test is manufactured by Matritech (Newton, MA, USA). In this study, the assay was positive in 33 patients. Of these, 18 with low-grade and 12 with high-grade lesions were true positive. Of the 20 NMP22, 8 negative cases were false-negative. Ten of 15 with negative histopathology were also negative for NMP22; 3 were false-positive, and 2 showed erratic results. Nine of 14 cases with atypical urine cytology were positive for NMP22. Eight of these showed low-grade carcinoma on histopathology. The sensitivity of BladderChek NMP22 test was 79%, whereas specificity was 80%. NMP22 BladderChek test is a useful adjunct to urine cytology in atypical and low-grade carcinoma

The NMP22 test detect the concentration of this tumor marker in voided urine and values greater than 7 NMP U/mL are usually considered suggestive of a tumor, although cut points ranging from 6 NMP U/mL to 10 NMP U/mL have been evaluated in an effort to improve predictive value. The authors of the study concluded, "NMP22 BladderChek test has a higher sensitivity compared to cytology and can be used as an adjunct to urine cytology in atypical and low-grade carcinoma. In a tertiary care center, limiting the use of NMP22 to these categories of lesions can reduce the overall cost of testing in developing countries.” The study was published in the November 2010 issue of Diagnostic Cytopathology.

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University College of Medical Sciences
Matritech