Since it has become well established that an elevated serum amylase level is the sine qua non of .a valid diagnosis of acute pancreatitis, this laboratory procedure has been accepted as an essential part of the routine work-up of the acute abdominal case. As data has accumulated and been analyzed, a considerable number of published reports have stressed that not, only is the serum amylase elevated in many non-pancreatic conditions, but the elevation is noted only for a limited time after the at ck of acute pancreatitis. Though much has been written about urinary amylase, the data and conclusions are con licting, and in consequence urinary amylase excretion is infrequently used in practice. Urinary excretion of amylase has been shown to be increased and to remain elevated for several days after the return of serum amylase levels to normal in patients with acute pancreatitis. It has also been found that the renal clearance of amylase tends to be greatly increased and is relatively greater than that of creatinine in patients with acute pancreatitis.
In 1969, Levitt, Rapoport, and Cooperband suggested an ingenious device whereby renal clearance of amylase expressed as a percentage of simultaneous creatinine clearance (Cam/Ccr) not only rose in acute pancreatitis to levels several times higher than normal, but also included, within the index ratio, information concerning the serum amylase, the urinary amylase and the state of renal, function to minimize irrelevant changes due to variations in renal function. Whether the increased amylase clearance, is specific for pancreatitis or whether it also occurs in other conditions that can be associated with elevated serum amylase levels is not known. But from their study of normal subjects and patients with ac to pancreatitis, they concluded that determination-of the CamCcr ratio would enhance the diagnostic value of amylase determinations. The present investigation reports an analysis of serum amylase, urinary amylase and der ved C../C.´ ratio in 42 normal controls and 26, patien s with acute pancreatitis, 5 with chronic pancreatitis and 51 with non-pancreatic disease, including 15 with acute cholecystitis, 17 with liver disease and 19 , with peptic ulcer at the Yonsei University, College of Medicine and Severance Hospital from March, 1975 through September, 1975.
1. In 42 normal subjects, the mean Cam/Ccr ratio was 1.75±0.76% (mean±S.D.), the serum amylase 126±26 units and the urinary amylase 219±171 units per 2 hours. Reasonable upper, ranges of normalcy can be established for these parameters i.e.: Cam/Ccr 3.27%
Serum amylase 178 units Urinary amylase 611 units per 2 hours
2. In 26 patients with acute pancreatitis, the serum amylase was elevated in all subjects who could be studied before 48 hours after the attack, and from 48 hours to the seventh day, the serum amylase was decreased to 195 units, but still higher than normal (p<0.01). The urinary amylase and Cam/Ccr ratio which were studied from 48 hours to the seventh day along with the serum amylase were also elevated to 930 units per 2 hours and 4.55% respectively (p<0.01).
The serum amylase and urinary amylase returned to normal in 12 and 11 patients respectively after 48 hours of acute pancreatitis. In contrast, only three of 26 patients with acute pancreatitis had a Cam/Ccr ratio below 3. 27%.
3. In chronic pancreatitis, even the serum amylase rose significantly (mean: 293 units, p<0. 01) during an acute recurrent attack, the urinary amylase and Cam/Ccr ratio remained within normal range in all 5 patients.
4. In patients who may have symptoms similar to acute pancreatitis without pancreatic disease, the mean serum amylase, urinary amylase and Cam/Ccr ratio were all within normal range. Though the serum amylase and/or urinary amylase may rose occasionally, the Cam/Ccr ratio disclosed normal levels in all patients.
This observation suggests that the renal permeability to amylase is altered in only acute pancreatitis among the conditions which may reveal similar symptoms of acute pancreatitis, and provides a basis for using the Cam/Ccr ratio in the differential diagnosis of hyperamylasemia.
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