Cystic Fibrosis

Diagnosis/Definition

Cystic Fibrosis (CF) is a genetic disease characterized by chronic lower respiratory infections, poor weight gain, steatorrhea, and abnormally high sweat electrolyte concentrations.

Initial Diagnosis and Management

Cystic Fibrosis is manifested by the clinical findings of recurrent lower respiratory symptoms, fat malabsorption syndrome, meconium ileus (at birth), or failure to thrive, either as isolated findings or in combination.
An abnormally elevated sweat chloride value (> 60 mEq/L) is usually diagnostic.
Other clinical findings which may prompt the clinician to order a sweat chloride include digital clubbing, rectal prolapse, persistent sinusitis (especially with nasal polyps), Pseudomonas aeruginosa cultured from either throat swab or sputum, bronchiectasis, unexplained hepatic dysfunction, bowel obstruction, salt depletion syndrome, and azoospermia in the young adult male.
When CF is suspected then a sweat chloride test or a blood test for DNA/CF mutation analysis should be ordered. The DNA analysis identifies approximately 95% of the CF gene mutations, so a negative test does not completely rule out CF.

Ongoing Management and Objectives

All patients with proven or suspected CF should be referred to the Division of Pediatric Pulmonology for specialty care at the time the diagnosis or tentative diagnosis is made.
Objectives of primary care management of CF following the initial specialty referral include evaluation and treatment of acute minor illnesses and injuries, and periodic well childcare and immunization.

Indications for Specialty Care Referral

When CF is considered a possible diagnosis, a sweat test should be ordered early in the evaluation. If a sweat test can not be performed easily (i.e., due to the child being unable to produce enough sweat for the test or the patient residing a long distance away from a lab which can perform the sweat test) then the DNA/CF mutation blood test should be ordered (as miscellaneous in CHCS).

All patients with a positive (chloride value >60 mEq/L) or borderline (chloride: 40-60 mEq/L) sweat chloride should be referred for specialty care. Patients with positive DNA/CF mutation blood tests should also be referred once the test results are known.

Patients with persistent symptoms suggestive of CF but with normal sweat tests and/or negative DNA/CF mutation blood tests should also be referred for evaluation.

Criteria for Return to Primary Care

Ongoing management of the child with CF is the responsibility of the pediatric pulmonary specialist.

Specialty care follow-up will not require primary care referral and will be established with the patient by the specialist.

Following initial diagnosis and establishment of an adequate treatment plan by the specialist, the patient may return to the primary caregiver for care of acute minor illnesses and injuries and for routine well child care.