Diagnosis and assessment of renal fibrosis: the state of the art

Chronic kidney disease (CKD) is defined as an alteration of kidney function and/or structure lasting for more than 3 months and is a major public health issue. Histologically, the severity of CKD correlates with the magnitude of kidney cortical interstitial fibrosis. Estimation of kidney fibrosis is crucial to assess prognosis and guide therapy in both native and allograft kidneys. Biopsy is currently the gold standard for assessing fibrosis with histological techniques. Although this procedure has become safer over recent years, complications and limitations remain. Given these restrictions, new, noninvasive techniques are necessary for the evaluation and follow-up of CKD patients. Radiological methods such as ultrasound and magnetic resonance imaging are emerging for assessment kidney fibrosis. These two techniques have advantages but also limitations. In addition to radiological assessment of fibrosis, urinary and plasma biomarkers are being developed and tested as predictive tools for histological lesions in the kidney. This article reviews the current evidence for these novel techniques in the evaluation of kidney interstitial fibrosis.