Which test is used to screen for cystic fibrosis?

Which test is used to screen for cystic fibrosis?

• A. Urine protein test
• B. Blood glucose test
• C. Sweat chloride test
• D. Liver function test

Answer: (C)

The sweat chloride test is the primary method used to screen for cystic fibrosis. This condition is caused by mutations in the CFTR gene, which plays a crucial role in the transport of chloride ions across epithelial membranes. In individuals with cystic fibrosis, the dysfunction of this gene leads to an abnormal increase in chloride concentration in sweat.

During the sweat chloride test, a small amount of a chemical is applied to the skin to stimulate sweating. The sweat produced is then collected, and the chloride concentration is analyzed. A higher than normal level of chloride (usually above 60 mmol/L) is indicative of cystic fibrosis.

This test is particularly valuable because it can be performed early in infancy, making it an effective screen for the condition, allowing for prompt diagnosis and management. Other tests, such as urine protein tests, blood glucose tests, and liver function tests, are not specific for cystic fibrosis and would not provide the diagnostic information necessary for this particular condition.