BACKGROUND In most treatment studies on acute pancreatitis, pancreatologists base their diagnosis on amylase/lipase levels more than three times above the upper limit of normal (>3n) and thus exclude patients with smaller enzyme level increases. The recommendations derived from the results of treatment studies do not take into account such patients. Non-pancreatologists frequently believe that only patients with high enzyme levels have a serious prognosis.

AIMS To question the assumption that high enzyme levels indicate severe, and conversely low enzyme levels indicate mild, acute pancreatitis.

PATIENTS/METHODS This retrospective study includes 284 consecutive patients with a first attack of acute pancreatitis. The cause was biliary in 114 (40%) patients, alcoholism in 83 (29%), other in 21 (7%), and unknown in 66 (23%). Patients were divided into two groups according to their serum enzyme levels (amylase: ⩽3n, n = 88; >3n, n = 196; lipase: ⩽3n, n = 51; >3n, n = 233). Renal impairment, indication for dialysis and artificial ventilation, development of pseudocysts, necessity for surgery, and mortality were taken as parameters of severity.

RESULTS The incidence of severity was the same for both the ⩽3n and >3n groups.

CONCLUSIONS The severity of acute pancreatitis is independent of the elevation in serum amylase/lipase level (⩽3n or >3n) on admission. Patients with only a slight increase can also have or develop severe acute pancreatitis. Patients with ⩽3n elevated enzyme levels on admission represent a substantial group that treatment studies have frequently overlooked. This is especially true for patients with alcohol induced acute pancreatitis whose amylase levels are lower than in other aetiological groups.