Urine biomarkers in juvenile-onset SLE nephritis.

Over 80 % of patients with juvenile-onset systemic lupus erythematosus will have renal involvement compared to 40 % with adult-onset disease. Up to 44 % of children who do have lupus nephritis (LN) progress to renal failure in early adulthood. Improved methods of detecting onset of LN would allow earlier treatment, which may prevent irreversible renal scarring and a decline in renal function. Current conventional markers of disease activity fail to adequately predict renal lupus flares and include proteinuria, complement levels, anti-double-stranded DNA antibodies and serum creatinine concentrations. Standardized histological classification is currently the gold standard for diagnosing and classifying LN, but its invasive nature limits routine use for monitoring, especially in a childhood population. Novel biomarkers need to be sensitive and specific-and preferably non-invasive and cost-effective. The most promising biomarkers in juvenile-onset LN include urinary neutrophil gelatinase associated lipocalin, monocyte chemoattractant protein 1 and transforming growth factor-beta, although many others have been identified and are under investigation. No one biomarker yet discovered is unique to LN, indicating an overlap in disease pathophysiology. It is likely that a combination of biomarkers will be required for assessing disease flare detection, response to treatment and prognostic information. Potential biomarkers require longitudinal validation in large paediatric, prospective cohorts to assess their ability to act as clinically useful adjuncts.