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Cystic Fibrosis

[Elevated IRT +/- DNA] 


Differential Diagnosis: Cystic Fibrosis (CF); gastrointestinal abnormalities are also causes of increased IRT. 

Condition Description: The cystic fibrosis transmembrane conductance regular (CFTR) protein regulates chloride transport that is important for function of lungs, respiratory tract, pancreas, liver, sweat glands and genitourinary tract. 

You Should Take the Following Actions:

  • Contact family and primary care physician to inform them of the newborn screening result and ascertain clinical status (meconium ileus, failure to thrive, recurrent cough, wheezing and chronic abdominal pain)
  • Determine sweat chloride (sweat test)
  • If cystic fibrosis is confirmed, clinical evaluation, and genetic counseling are indicated
  • Report findings to state newborn screening program (Carleigh Soule at 307-777-6297) 

Confirmation of Diagnosis: Varies with screening test. Infants with highly elevated immunoreactive trypsinogen (IRT) may be considered screen positive. Moderately elevated IRT results are followed with second tier tests for either IRT or CFTR mutation panels. If screen positive, follow-up with sweat test. 

Clinical Expectations: Deficient chloride transport to lungs causes production of abnormally thick mucous leading to airway obstruction, neutrophil dominated inflammation and recurrent and progressive pulmonary infections. Pancreatic insufficiency found in 80-90% of cases. 

Additional Information: (Click on the name to take you to the website) 

Gene Tests/Gene Clinics                                             Wyoming Department of Health                                

Online Mendelian In Men                                             Colorado Newborn Screening                            

Genetics Home Reference                                           Cystic Fibrosis Foundation                                     


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