MDK and acute kidney injury: Post-operatively, there were 12/20 (60%) biomarkers which were significantly elevated in patients with PTOS-AKI (Table 2): sTNFR1 (serum and urine), sTNFR2 (serum), H-FABP (serum), NGAL (plasma and urine), IL-12p40 (serum), MIP-1α (plasma), MCP-1 (plasma), midkine (serum), IL-6 (plasma), and sIL-2Rα (serum).