Abstract
Interest in microRNAs (miRNAs) has dramatically increased in recent years not only because they regulate mRNA expression, and thus many physiological or pathophysiological processes, but also because they could serve as biomarkers. Next to analysis of tissue miRNA expression, measurement in body fluids such as blood or urine is attractive because miRNA in microvesicles or bound to protein is very stable. Currently it is unclear whether these circulating miRNAs are tissue and disease specific or represent more general pathologies like inflammation. In addition pre-analytical sample handling and variable analysis techniques affect the results and thus much more work needs to be done before one can draw a final conclusion about their clinical utility.