LETTER Timing of renal replacement therapy: is it when or how much?

Leite and colleagues addressed the importance of early initiation of renal replacement therapy (RRT) in decreasing mortality and ICU length of stay in patients with Acute Kidney Injury Network stage 3 [1]; however, we have a few concerns regarding the study. The impact of fluid balance on morbidity and mortality in patients with septic shock, especially with acute kidney injury, cannot be understated [2]. This impact can affect ventilator-free days and the length of ICU stay. The authors did not show their first 6-hour and 24-hour fluid balances. Whether the reported improvement was due to the timing of initiation of RRT, the dose, or misrepresentation of the study population is an unanswered question. Were improvements seen in morbidity and mortality simply because more volume was removed because of early initiation of RRT or because patients with more severe disease were not represented in the study? The overall in-hospital mortality in this study was 72%, which is extremely high. In previous prospective studies, the overall mortality rate was just 46 % [3]. Were there other variables in management that were not addressed, such as the time from admission to antibiotic treatment, adequate fluid resuscitation, or initiation vasopressor treatment, which may have led to the high mortality in this population [4]? Authors ’ respons

Quantitative Renal Echogenicity as a Tool for Diagnosis of Advanced Chronic Kidney Disease in Patients with Glomerulopathies and no Liver Disease

Background/Aims: Glomerulopathy patients are prone to developing transitory reduced glomerular filtration rate (GFR), which can be difficult to differentiate from irreversible chronic kidney disease (CKD). Renal ultrasound can be useful, but differently from renal length, quantitative renal echogenicity has not been formerly evaluated regarding its capacity to identify irreversible advanced CKD. Methods: A prospective study was performed, where quantitative renal echogenicity was performed during renal biopsy in patients with suspected glomerular disease (n=197). Quantitative echogenicity was measured as the inverse of the ratio between the mean pixel densities of the renal cortex and adjacent liver using ScionImage software. Patients were followed during a six-months period to ascertain irreversible advanced CKD. Quantitative renal echogenicity and histopathology parameters discriminatory capacity were compared regarding their capacity to detect advanced and irreversible CKD - estimated GFR less than 30mL/min/1.73m2 confirmed after a six-month follow-up. Results: At renal biopsy, the mean eGFR was 53.9±33.6 mL/min/1.73m2 and 63 (32.0%) patients had an eGFR less than 30 mL/min/1.73m2. Mean kidney/liver echogenicity ratio was 1.06±0.19 and it was inversely correlated with eGFR at follow-up (r=-0.684, p<0.001). Multivariate analysis was performed to create a histopathology index that correctly identifies irreversible advanced CKD. Renal echogenicity discriminatory capacity to identify irreversible advanced CKD was 0.793 (0.719 -0.867), similar to the histopathology index. Elevated renal echogenicity with best discriminatory capacity was a kidney/liver ratio greater than 1.15. This cutoff had a predictive positive value of 92% in patients with eGFR less than 30mL/min/1.73m2. Conclusion: Quantitative renal echogenicity can be a useful tool in patients with glomerular disease and normal kidney size (>8cm) to identify those patients with irreversible advanced CKD