Urine: An under-studied source of biomarkers in multiple sclerosis?

There remains a need for sensitive and reliable biomarkers that can be used longitudinally in multiple sclerosis. Whilst both CSF and MRI have been extensively studied, they remain invasive and expensive methods of investigation. On the contrary, urine provides a valuable fluid which is readily available for serial sampling. Some work has been done on urinary biomarkers in multiple sclerosis; however, urinary biomarkers have not been extensively studied and validated for use in routine clinical practice, and urine remains understudied and underutilised. In this review the use of neopterin, urinary free light chains, nitric oxide metabolites and urinary myelin basic protein-like protein as potential biomarkers that have been identified in urine are discussed, and avenues for future study are raised.