Does hyperamylasemia in choledochal cyst indicate true
pancreatitis? An experimental study
Naoto Urushihara, Takuji Todani, Yasuhiro Watanabe, Sadashige Uemura, Yoshiki
Morotomi, Zhong-Qiu Wang
Eur J Pediatr Surg 5: 139-142, 1995
Patients with choledochal cyst often have repeated attacks
of abdominal pain accompanied by hyperamylasemia, and they may be diagnosed
as having acute pancreatitis. However, the attacks generally tend to subside
in a short period by conservative treatment, and evidence of pancreatitis
is rarely observed at the time of surgery. Choledochal cyst is commonly
associated with pancreatobiliary maljunction, and high concentrations of
pancreatic enzymes in bile are usually observed. When the bile duct pressure
increases due to obstructive cholangitis, pancreatic enzymes in bile may
regurgitate into the blood stream. Cholangiovenous reflux of amylase might
cause hyperamylasemia. In order to investigate the mechanism of hyperamylasemia
by cholangiovenous reflux, canine pancreatic juice or bile from a patient
with choledochal cyst was injected into the obstructed common bile duct
in dogs. The pancreatic enzymes in bile could readily enter into the blood
stream at the pressure level of I 5 mmHg or more in the bile duct. The peak
amylase level in the thoracic lymph was observed to be more than 4 times
higher than that in the blood serum, and the lymph flow during 30 minutes
increased significantly from 8.1 to 20.4 ml at the bile duct pressure level
of 20 mmHg. The reflux of amylase in bile into the blood stream via both
the hepatic vein and thoracic duct might result in hyperamylasemia in the
patients with choledochal cyst.
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