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PABA screening test for exocrine pancreatic function in infants and children
Insights
A novel test using N-benzoyl-L-tyrosyl-PABA measures pancreatic function by tracking P-Aminobenzoic acid (PABA) excretion. This noninvasive method shows promise for diagnosing exocrine pancreatic insufficiency, especially in newborns.
Area of Science:
- Biochemistry
- Gastroenterology
- Pediatrics
Background:
- Exocrine pancreatic insufficiency (EPI) affects nutrient absorption and requires accurate diagnostic methods.
- Assessing pancreatic enzyme activity is crucial for managing conditions like cystic fibrosis (CF).
- Current diagnostic tools for pancreatic function can be invasive or complex.
Purpose of the Study:
- To evaluate a new noninvasive diagnostic test for exocrine pancreatic function.
- To assess the utility of N-benzoyl-L-tyrosyl-PABA hydrolysis and P-Aminobenzoic acid (PABA) excretion as a biomarker for pancreatic insufficiency.
- To compare PABA recovery in healthy children, CF patients, and newborn infants.
Main Methods:
- Oral administration of N-benzoyl-L-tyrosyl-PABA (0.015 g/kg) to participants.
- Measurement of urinary PABA recovery over 6 hours as an indicator of pancreatic chymotrypsin activity.
- Comparison of PABA recovery percentages across control groups, CF patients, and neonates.
Main Results:
- Healthy controls showed a mean 6-hour PABA recovery of 58.5% (+/- 11.2 SD).
- Patients with cystic fibrosis exhibited significantly lower PABA recovery (P < 0.001) with no overlap with controls.
- Newborn infants had a mean 6-hour PABA recovery of 23.4% (+/- 17.7 SD), with some overlap with CF patient results.
Conclusions:
- Urinary PABA recovery after N-benzoyl-L-tyrosyl-PABA administration is a sensitive index of exocrine pancreatic function.
- The test effectively differentiates healthy individuals from those with CF-related pancreatic insufficiency.
- Further investigation is warranted to validate this promising, noninvasive test in newborns and younger infants.
Abstract:
P-Amino-benzoic acid (PABA) is split specifically by pancreatic chymotrypsin from the synthetic tripeptide N-benzoyl-L-tyrosyl-PABA. The urinary excretion of absorbed PABA serves as an index for exocrine pancreatic function. The peptide (0.015 g/kg) was administered orally to 20 controls (aged between 5 months and 16 years), 6 patients with exocrine pancreatic insufficiency caused by cystic fibrosis (CF), and 9 newborn infants. In the controls the mean 6-hour PABA recovery was 58.5% (+/- 11.2 SD). Recovery in patients with CF was lower (P less than 0.001) with no overlap. In newborn infants the mean 6-hour PABA recovery was 23.4 (+/- 17.7 SD); overlapping in 3 instances with the results in CF patients. This simple, noninvasive test thus appears promising and merits further investigation in younger infants, especially newborns.