The use of biomarkers for assessing HAART-associated renal toxicity in HIV-infected patients.

Renal toxicity has become an important issue in HIV-infected patients receiving highly active antiretroviral therapy (HAART). Several biomarkers are available for monitoring renal function, although no consensus exists on how best to apply these tools in HIV infection. The best biomarker is the glomerular filtration rate (GFR), and several creatinine-based estimates equations of GFR are widely used in HIV infection, with clinical advantages for the equation developed by Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI). Although serum cystatin C has been proposed as a more sensitive marker of renal dysfunction in HIV infection, it may be affected by ongoing inflammation. Tubular dysfunction can be simple or complex, depending on whether the tubular transport of one or more substances is affected. Multiple renal tubular dysfunction or Fanconi syndrome is characterized by alterations in the reabsorption of glucose, amino acids, phosphate and often also bicarbonate. Therefore, Fanconi syndrome would be the tip of the iceberg, and the most unusual and severe manifestation. In the last years, several low molecular weight proteins as markers of tubular alteration, including retinol-binding protein, b2-microglobulin, and neutrophil gelatinase associated lipocalin have become available. Different studies have shown differences in urine concentrations of these proteins in patients receiving tenofovir, but again, no consistent data have shown their clinical usefulness in predicting the clinical consequences of tubular alteration. Thus, we review findings from recent studies performed in this area to describe the performance of new biomarkers for renal damage in HIV-infected patients.