Diagnostic Procedures, Clinical Characteristics and Counseling in Cystic Fibrosis

Abstract

Most patients with the eventual diagnosis of cystic fibrosis (CF) present in the first months of life with classical symptoms such as meconium ileus, failure to thrive and recurrent or persistent cough. Disease manifestations are obvious, progressive and concern different organ systems. In these patients the standard diagnostic test is the sweat test. A sweat chloride concentration of >60 mmol/l confirms the clinically suspected diagnosis. Since the discovery of the CFTR (CF transmembrane conductance regulator) gene, it has become obvious that the clinical spectrum is broad. Several categories of patients have been proven to carry two CFTR mutations: patients with classic CF; patients with milder symptoms and disease onset during adolescence or even adulthood; patients with a single clinical feature, e.g. recurrent pancreatitis, sclerosing cholangitis, ‘idiopathic’ bronchiectasis, and male infertility. The latter two categories are described as atypical or non-classic CF. It is very important that these patients know that they do not suffer from classic CF, but that they have a risk factor for developing a CF-like disease that warrants intermittent follow-up by physicians familiar with the very wide disease spectrum. In patients with classic CF, chronic progressive bacterial sinopulmonary infection and inflammation with intermittent exacerbations are the most typical disease manifestations. Ninety percent of patients have pancreatic insufficiency. Postpubertal men are sterile. During their lifetime CF patients may develop disease manifestations and complications in the sinuses, lung, pancreas, liver, intestine, esophagus, bone, joints, etc. The complex mix of possible disease manifestations makes each patient unique. As they become older, the number of complications tends to increase and their physical condition tends to worsen. Many young adult CF patients have decreased exercise tolerance because of advanced lung disease; 20% have CF-related diabetes mellitus. Classic CF is a life-shortening disorder and, even with the most intense treatment and follow-up, the current median survival is around 34 years. This puts an enormous psychological stress on patients and families. Counseling to prevent disease recurrence in siblings and in the extended family is important and complex.

Diagnosing Cystic Fibrosis in the 21st Century—A Complex and Challenging Task

“…As per the European Diagnostic Working Group, patients are categorized as having classic CF if they exhibit one or more phenotypic characteristics, ST above 60 mmol/L, pancreatic insufficiency/sufficiency, and a severe prognosis. Patients without these criteria fall into the non-classic or atypical category, many of whom have mild lung disease and pancreatic insufficiency [142].…”