HAMP and acute kidney injury: The observations of Ho et al. were corroborated by an independent observational study measuring hepcidin through ELISA in 100 cardiac surgery patients [12]: urine hepcidin was 3–7 times higher 6 and 24 hours after surgery in AKI-free patients (n = 91) compared to 9 patients who developed AKI (defined as ≥50% rise in serum creatinine or urine output <0.3 ml/kg/hr during the first seven postoperative days).