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Immunoreactive trypsin in cystic fibrosis
Insights
Newborn screening for cystic fibrosis (CF) using blood immunoreactive trypsinogen (IRT) is effective and cost-efficient. Elevated IRT levels in CF patients correlate with pancreatic function, aiding in diagnosis and management.
Area of Science:
- Biochemistry
- Pediatrics
- Genetics
Background:
- Elevated blood immunoreactive trypsinogen (IRT) in infants with cystic fibrosis (CF) has been observed since 1979.
- Mass newborn screening for CF using IRT assays is practical and cost-effective compared to other screening programs.
Purpose of the Study:
- To understand the importance of elevated IRT in CF infants.
- To evaluate the practicality and cost-effectiveness of mass newborn screening for CF using IRT.
- To explore the relationship between IRT levels and pancreatic exocrine function in CF patients.
Main Methods:
- Review of studies on IRT levels in CF infants and patients.
- Comparison of IRT screening costs with existing programs.
- Analysis of IRT levels in relation to pancreatic enzyme secretion in CF patients.
Main Results:
- Mass newborn screening for CF using IRT is feasible and detects nearly all CF newborns.
- IRT levels in older CF patients reflect pancreatic exocrine function, differentiating between preserved and diminished secretion.
- An altered relationship between pancreatic exocrine secretion and circulating IRT exists in all CF patients.
Conclusions:
- IRT is a valuable biomarker for newborn screening of CF.
- IRT levels can assist in assessing pancreatic function in CF patients.
- A secretory obstructive defect, reflected in altered IRT levels, is a common feature in CF patients.
Abstract:
Since the first observation in 1979 that CF infants have elevated blood IRT, studies in various centres have enabled us to more fully understand the importance of this phenomenon. There is increasing evidence to show that mass newborn screening for CF using the IRT assay is practical and is capable of detecting essentially all CF newborns at a cost comparable to existing screening programs for other disorders such as Hypothyroidism. Although the elevated IRT levels seen in infancy in CF soon decrease, IRT levels in older CF patients appear to quite closely reflect the capability of that patient to secrete pancreatic enzymes and can be helpful in separating CF patients whose ability to secrete enzymes is preserved, from those with diminished exocrine pancreatic function. In all CF patients there appears to be an altered relationship between pancreatic exocrine secretion and circulating IRT levels as compared to control patients. This is probably one further manifestation of a secretory obstructive defect which although not uniformly severe, is common to all CF patients.