Acute pancreatitis (AP) is a relatively common disease in New Zealand (29.3/100,000/year). Severe AP (SAP), in 25% of patients with AP, has a high mortality (20-40%) due to infected necrosis and multiple organ dysfunction syndrome (MODS). Critical to the successful management of SAP is accurately predicting which patients will develop SAP and accurately monitoring their response to treatment. Current approaches fall short of what is required. The pathogenesis of MODS involves mitochondrial dysfunction in vital organs. This has been demonstrated in our laboratory using tissue samples from vital organs in studies of experimental AP. Tissue samples from these organs cannot be obtained in clinical practice. The aim of this research has been to develop a measure of mitochondrial function (MF) in peripheral white blood cells (WBC) and to evaluate it as a predictor of SAP and as a marker of response to established (enteral nutrition) and novel (mitochondrial targeted) treatments.