While we adjusted for hemodynamic instability with non-renal APACHE II scores in multivariable modeling, as well as investigated the impact of vasopressor receipt while in the ICU on serum renin concentrations in additional analysis, future work would benefit from precise measurements of vasopressor support in order to disentangle the contribution of shock (and vasopressor support) from AKI in terms of elevations in serum renin concentrations in critically ill patients. The gene discussed is REN; the disease is acute kidney injury.