Laboratory Diagnosis of Cystic Fibrosis

A patient has a sweat conductivity result of 60 mmol/L. What would be the estimated corresponding sweat chloride concentration?

45 mmol/L

Which of the following tests is appropriate to CONFIRM the diagnosis of cystic fibrosis (CF)?

A quantitative sweat chloride test

Approximately 47% of individuals with cystic fibrosis are homozygous for the F508del mutation of cystic fibrosis transmembrane conductance regulator (CFTR). How does this mutation affect CFTR?

Block in processing

What is the result of the defective cystic fibrosis transmembrane conductance regulator (CFTR) protein on chloride reabsorption in the sweat ducts and chloride concentration in sweat?

Decreased chloride reabsorption in the ducts and increased chloride concentration in sweat

What is the goal of physiotherapy with inhaled medications in the treatment of CF?

Improve lung function and decrease lung infections

What causes a decrease in digestive enzyme secretion from the pancreas into the intestines in patients with cystic fibrosis (CF)?

Mucus blockage of the pancreatic duct

Patients who are homozygous for the F508del mutation of cystic fibrosis transmembrane conductance regulator (CFTR) exhibit which of the following characteristics?

Pancreatic insufficiency

You are performing a sweat test using the Macroduct® system. At the end of 30 minutes, you observe that the patient is not producing very much sweat in the Macroduct® coil. Visually, you estimate it is between 5-10 µL. What should you do?

Stop the collection and quantitate the volume collected with a micropipet. If it is less than 15 µL report out the result as "quantity not sufficient" (QNS).

A 3-week-old female with no signs or symptoms of cystic fibrosis (CF) has a positive newborn screening (NBS) test result for CF. The NBS is based on genotyping. The baby is then referred for sweat chloride testing. The sweat chloride result is 15 mmol/L, which is in the normal range. What do these results most likely indicate?

The patient is a carrier of CF

Which of the following is NOT a common manifestation of cystic fibrosis (CF)?

renal disease