Cystic fibrosis diagnostic test

Carmen is a pale 20-year-old lady. Like many cystic fibrosis patients, she was diagnosed when she was a baby her problem was suspected when she suffered repeated respiratory infections and failed to gain weight as expected. Patients with cystic fibrosis secrete a high concentration of NaCl in their sweat and this forms the basis of an early diagnostic test for the condition. 

Sweat glands have sympathetic cholinergic innervation. Patients with cystic fibrosis secrete a large amount of salt in their sweat and this forms the basis of a diagnostic test for the condition. 

The analysis of sweat for increased electrolyte concentration is used to confirm the diagnosis of cystic fibrosis (CF). CF is recognized as a syndrome with a wide spectrum of clinical presentations associated with a defect in the cystic fibrosis transmembrane conductance regulator protein (CFTR), a protein that normally regulates electrolyte transport across epithelial membranes. (For a more detailed discussion of CF, see Chapter 40.) Several hundred mutations of CFTR have been identified. Although mutational analysis is available, it is not informative in all cases, and the sweat test remains the standard for diagnostic testing. ... 

Walhs C, Leung T, Cubitt D, Reynolds A. Stool elas-tase as a diagnostic test for pancreatic function in children with cystic fibrosis. Lancet 1997 350 1001. 

Prenatal diagnosis of genetic disease is normally carried out on a sample of amniotic fluid obtained by amniocentesis or by chorionic villus sampling (CVS). Conventional diagnostic tests for diseases such as cystic fibrosis can take as long as 2 weeks. Results of a PCR test can be available in 1 day. If the option to terminate a pregnancy is taken, this time savings can... 

W Ion selective electrodes can have many diagnostic applications in biology. For example, the chloride electrode is being used to assay chloride ion activity in the sweat of babies as a diagnostic test for cystic fibrosis. Another application with a potential for direct health use falls in the area of dental research. Calcium and fluoride electrodes are being used to study the relationship between tooth decay and saliva ion composition. 

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