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Cystic fibrosis serum pancreatic amylase. Useful discriminator of exocrine function
Insights
Serum pancreatic amylase isoenzyme (P isoamylase) activity offers a simple test for pancreatic exocrine function in cystic fibrosis patients over 1.5 years old. This test effectively differentiates between sufficient and insufficient pancreatic function in this age group.
Area of Science:
- Biochemistry
- Pediatrics
- Genetics
Background:
- Cystic fibrosis (CF) often leads to pancreatic exocrine insufficiency.
- Standard tests for pancreatic exocrine function are complex and time-consuming.
Purpose of the Study:
- To evaluate serum pancreatic amylase isoenzyme (P isoamylase) activity as a simple diagnostic marker for pancreatic exocrine function in cystic fibrosis patients.
- To compare P isoamylase activity with established pancreatic function tests.
Main Methods:
- Serum P isoamylase activity was measured in 27 cystic fibrosis patients (newborn to 46 years).
- P isoamylase levels were compared with duodenal secretions and 72-hour fecal fat absorption tests.
- Age-matched normal ranges were used for comparison.
Main Results:
- Patients over 17 months with pancreatic exocrine insufficiency showed low serum P isoamylase activity.
- Patients over 1.5 years with adequate pancreatic function had normal or high P isoamylase activity.
- Neonates, both with and without CF, exhibited very low P isoamylase levels.
Conclusions:
- Serum P isoamylase activity is a simple and useful discriminator of pancreatic exocrine function in cystic fibrosis patients over 1.5 years of age.
- This test can aid in diagnosing pancreatic insufficiency in this population.
Abstract:
To develop a simple test for pancreatic exocrine function in patients with cystic fibrosis, we compared serum pancreatic amylase isoenzyme (P isoamylase) activity with the more complex standard tests of pancreatic function. Twenty-seven patients with cystic fibrosis, newborn to 46 years of age, were studied. All patients over 17 months old with evidence of pancreatic exocrine insufficiency, as manifested by abnormal duodenal secretions and/or abnormal 72-hour fecal fat absorption, had serum P isoamylase activity below the age-matched normal range; patients with adequate pancreatic function (aged 2 to 46 years) had P isoamylase activity in or above the normal range. Although both normal neonates and neonates with cystic fibrosis have very low levels of serum P isoamylase activity, in patients over 1 1/2 years of age serum P isoamylase activity may serve as a simple and useful discriminator of pancreatic exocrine function in patients with cystic fibrosis.