secretin test, a test of pancreatic function after stimulation with the hormone secretin. The test measures the volume and bicarbonate concentration of pancreatic secretions. Normal volume findings are 2 to 4 mL/kg body weight HCO3 (bicarbonate): 90 to 130 mEq/L. A lower-than-normal volume suggests an obstructing malignancy or cystic fibrosis. Reduced bicarbonate and amylase concentration is usually diagnostic of chronic pancreatitis.