Cystic Fibrosis

Cystic Fibrosis affects the pancreas, liver and intestines, mostly the lungs, and provides a suitable environment for pathogens in these organs and paves the way for infection. The respiratory system is one of the main systems affected by this disease. Cystic Fibrosis causes mucus plugs especially in small airways and leads to respiratory failure.

Cystic Fibrosis, inherited autosomal recessively, is the most common genetic disease in the Caucasian race and the incidence rate is 1/2,500. In Turkey, the estimated incidence rate in the studies conducted is 1/3000.

While it was defined as a fatal childhood disease in the last century, the life expectancy of patients today has prolonged significantly.

Newborn screening is critical in the diagnosis and detection of symptoms of Cystic Fibrosis. Signs and symptoms of Cystic Fibrosis vary depending on the severity of the disease. Symptoms may progress or regress over time even in the same person. In some patients, symptoms may not be observed until adolescence or adulthood. People with cystic fibrosis have a higher rate of salt in their sweat than normal people. Even when parents kiss their children, they may notice the excess salt in their sweat. 

The majority of other symptoms occur in the respiratory or digestive system.  However, atypical symptoms such as pancreatitis, diabetes, infertility may also occur.

Symptoms due to thick and sticky mucus obstructing the respiratory tract in Cystic Fibrosis:

• Persistent productive cough

• Wheezing

• Shortness of breath

• Exercise intolerance

• Recurrent pulmonary infections

• Persistent sinusitis and nasal polyps

The pathway that carries digestive enzymes from the pancreas to the small intestine is blocked. After this blockage, digestive enzymes cannot be used. The symptoms that occur due to the inability to digest the food eaten:

• Foul-smelling, greasy stools

• Growth retardation

• Meconium ileus

• Constipation

The most important laboratory finding in the diagnosis of Cystic Fibrosis is the detection of chloride concentration above 60 mmol/L in 100 mg sweat collected in three different periods by pilocarpine iontophoresis. This test is sufficient for a definitive diagnosis.

In some diseases other than Cystic Fibrosis (hypothyroidism, malnutrition, hereditary nephrogenic diabetes insipidus, glycogen storage diseases, untreated adrenal insufficiency), chloride concentrations in sweat may be high. A differential diagnosis can be made with history, physical examination and other laboratory tests. In addition to more advanced methods such as measuring the electrical potential difference across the nasal epithelium and genetic examination; easier tests such as liver function tests (LFTs), abdominal ultrasonography, evaluation of pancreatic functions, determination of fat malabsorption, and microbiological examination of respiratory secretions are also helpful in the differential diagnosis of cystic fibrosis.

In Cystic Fibrosis, there is a mutation in the gene encoding chloride channels and a defect in the cAMP-dependent Cystic Fibrosis Transmembrane Protein (CFTR). The most common mutation in Europe and North America is the delF508 mutation. In our country, delF508 mutation is present in approximately 25%.

There is no definitive treatment available for Cystic Fibrosis. Various treatments are used to alleviate patients' complaints and reduce the risk of comorbidities. These include drugs that reduce the thickness and stickiness of mucus, antibiotics, drugs that dilate the airways, certain intestinal surgeries and physical therapy applications.

In Cystic Fibrosis, the therapeutic goal should include all the mechanisms that lead to the development of the disease in the respiratory tract. Clearance of the hard, sticky, abundant secretions in the respiratory tract is a measure that relieves patients in every period and positive results are obtained with various physiotherapy methods and instruments. Bronchodilators can be used before physiotherapy to increase mucus clearance and for bronchodilation and may also support the treatment of hypersensitive airways, which are common in patients. 

The key point in the treatment of gastrointestinal symptoms in Cystic Fibrosis is to ensure that pancreatic enzymes are taken immediately before or with meals. When pancreatic enzymes including protease, amylase and lipase are taken in this way, malabsorption findings disappear, appearance and number of stools return to normal, and the patient begins to gain weight rapidly.

References

1. Welsh M., Ramsey B.W., Accurso F.J., Cutting G.R. Cystic fibrosis. In: Scriver C.R., Beaudet A.L., Sly W.S., Valle D., Childs B., Vogelstein B., editors. The Metabolic and Molecular Basis of Inherited Disease. 8th ed. McGraw Hill; New York, NY, USA: 2001. pp. 5121–5188

2. Gürson CT, Sertel H, Gürkan M, Pala S. Newborn screening for cystic fibrosis with the chloride electrode and neutron activation analysis. Helv Paediatr Acta 1973; 28: 165–74

3. Yilmaz E, Erdem H, Ozguc M, Coskun T, Ozcelik U, Gocmen A, et al. Study of 12 mutations in Turkish cystic fibrosis patients. Hum Hered 1995;45:175-7.

4. Farrell PM, et al. Diagnosis of Cystic Fibrosis: Consensus Guidelines from the Cystic Fibrosis Foundation. J Pediatr. 2017 Feb;181S:S4-S15.e1. doi: 10.1016/j.jpeds.2016.09.064. Erratum in: J Pediatr. 2017 May;184:243. PMID: 28129811.

5. Cohen-Cymberknoh M, et al. Managing cystic fibrosis: strategies that increase life expectancy and improve quality of life. Am J Respir Crit Care Med. 2011 Jun 1;183(11):1463-71. doi: 10.1164/rccm.201009-1478CI. Epub 2011 Feb 17. PMID: 21330455.

6. Ramsey BW. Management of pulmonary disease in patients with cystic fibrosis. N Engl J Med. 1996 Jul 18;335(3):179-88. doi: 10.1056/NEJM199607183350307. Erratum in: N Engl J Med 1996 Oct 10;335(15):1167. PMID: 8657217.