Amylase:creatinine clearance ratios, serum amylase, and lipase after operations with cardiopulmonary bypass.

Forty-two adults who underwent cardiac operations were studied prospectively for evidence of clinical or subclinical pancreatitis. Clinically detectable pancreatitis was not seen. Serum amylase and lipase levels did not change significantly following operation. The amylase:creatinine clearance ratio (ACCR) immediately following operation was abnormally elevated in 31% of the samples obtained, and the mean ACCR increased from 2.08 +/- 1.85% before operation to 6.2% +/- 6.77% (P less than 0.05). An abnormally elevated ACCR was most often associated with a low urine creatinine concentration. The mean urine creatinine level decreased significantly from 78 +/- 53 mg/dl before operation to 38 +/- 49 mg/dl immediately following operation (P less than 0.02), and 73% of the samples obtained at that time had an abnormally low urine creatinine level (P less than 0.01). The abnormalities observed in ACCR and urine creatinine could not be related to any of several variables presumed to reflect the degree of perioperative physiologic stress, nor could they be related to postoperative hemodynamic performance. It was concluded that ACCR rises following cardiac operation because of perioperative changes in renal function, and not as a reflection of subclinical pancreatic injury.