Diagnostic Relevance of microRNAs in Other Body Fluids Including Urine, Feces, and Saliva.

Beside blood-borne circulating miRNAs, miRNAs have been identified in other body fluid and excrements including stool, bile, saliva, and urine. Given the direct link of these body fluids to certain organs, their analysis for potential diagnostic miRNA markers is plausible. Several independent findings underline the potential utility of stool-derived miRNAs in the diagnosis of colorectal and pancreatic cancer. Given the difficulties in the diagnosis of cholangiocellular cancer, biliary miRNAs might be envisaged as useful markers. Several miRNAs have been identified in the saliva that could be associated with diseases, including tumors of the oral cavity. The urinary pool of miRNAs could be exploited for the diagnosis of urinary tract diseases and some appear to enable early diagnosis. In this chapter, we present findings supporting the potential diagnostic utility of fecal, biliary, salivary, and urinary miRNAs focusing mostly on tumors.