Quantification of gene expression in urinary sediment for the study of renal diseases

Urinalysis has been used extensively in clinical practice to aid in the diagnosis of various renal diseases. With the advances in technology of molecular biology, gene expression and proteomic studies are now possible for urinary sediment. In this review article, we focus on the quantification of messenger RNA expression in urinary sediment by reverse-transcription and real-time quantitative polymerase chain reaction. Recently, this technique has been explored for three potential applications: (i) distinguishing the different causes of kidney disease; (ii) assessment of kidney disease activity, progression and response to therapy; and (iii) as a tool to study the pathogenesis. Although the method is simple and non-invasive, it requires further research to define the role in routine clinical practice. At this moment, the technique should only be considered experimental albeit promising.