After acceptance patients will be randomized by computer-generated sequences of random numbers in the two groups Group one (1) will receive a bolus of fluid 20 ml / kg of Ringer's solution for infusion within one hour of the diagnosis and the group two (2) will receive a bolus of fluid 40 ml / kg of Ringer's solution for infusion within one hour of the diagnosis. All patients who have the diagnosis of acute pancreatitis, but did not agree to participate in research or have some other exclusion criteria will be treated according to the standards of good clinical practice and the recommendations of the current clinical guidelines for the treatment of acute pancreatitis. Exclusion criteria beside refusal to sign informed consent are: age less than 18 years, pregnancy, patients with physical signs of heart failure, previously known congestive heart failure (NYHA III - IV) and severe kidney disease more than one month before the diagnosis of acute pancreatitis (defined as severe reduction in eGFR less than 30 ml/min/1.73 m2). Patients who develop acute renal failure as a result of acute pancreatitis will be involved in research .