Biomarkers of cardio-renal damage in chronic kidney disease: one size cannot fit all

Biomarkers are useful tools for diagnosis and risk assessment of acute kidney injury and acute heart failure, particularly in ICU patients. Most biomarkers are produced or cleared by the kidney, so the presence of chronic kidney disease may affect their clinical reliability, particularly if the putative diagnosis of acute kidney injury or acute heart failure is based on a single measurement/single threshold approach. Better alternatives, such as establishing different diagnostic cutoff values per different chronic kidney disease strata or evaluating the diagnostic performance of a delta value (change from baseline levels) instead of a single threshold, should be carefully considered in critically ill patients with renal impairment and other co-morbidities. Chronic kidney disease (CKD) is highly prevalent in the ICU population and conveys a higher risk of developing both acute kidney injury (AKI) and acute heart failure (AHF). Early serum and urine biomarkers of AKI and AHF may improve diagnosis and risk stratification. Most biomarkers are affected by renal function impairment, however, so the presence of CKD may hamper their predictive capacity.