How does serum amylase compare to serum lipase in the diagnosis of acute pancreatitis?
Serum amylase rises typically within 6-12 hours of AP onset and declines gradually over 3-5 days. Serum lipase is elevated within the first 24 hours of AP and remains elevated for a longer period than serum amylase. Therefore, it may be more valuable than serum amylase in patients with delayed onset of suspected AP. Sensitivity of serum amylase and lipase are similar; however, some feel that specificity is greater with serum lipase given that most lipase stems from the pancreas. Fractionation of elevated total serum amylase into pancreatic-type (p-type) and salivary-type (s-type) isoamylase is available in most laboratories and may help in the diagnosis of AP. Recall that abdominal pathology (i.e., intestinal obstruction) can cause elevation of pancreatic isoamylase.
