Chloride (Sweat) Ise Sweat

The chloride sweat test is used to measure the amount of chloride in the sweat. This test helps in the diagnosis of cystic fibrosis.

What is Chloride?

Chloride is an important mineral and a type of electrolyte which works with other electrolytes like potassium and sodium. Chloride is an electrically charged mineral and helps balance acids and bases in the body. It also moves fluid in and out of the cells. This helps in maintaining electrical neutrality and water balance. This movement is regulated through a protein called the cystic fibrosis transmembrane conductance regulator (CFTR). It acts as a channel by letting chloride out of the cells and into the surrounding fluid, which will reduce sodium absorption. Hence low levels of chloride may lead to dehydration and high levels indicate improper functioning of kidneys.

What is Cystic fibrosis?

Cystic fibrosis is an inherited disorder which causes severe damage to the lungs, digestive system, and other organs in the body. This is due to a mutation in each of the two copies of cystic fibrosis transmembrane conductance regulator gene (CFTR). With these mutations, the CFTR protein will be dysfunctional or absent. When the CFTR is dysfunctional or absent, chloride cannot move out of the ducts into the surrounding fluid. This might result in thick and viscous mucus. As CFTR levels are mostly high in epithelial cells lining the internal surface of the lungs, pancreas, sweat glands, salivary glands, intestine, and other reproductive organs, these are most affected by cystic fibrosis. Dysfunctional CFTR or absent CFTR may result in high levels of chloride in sweat, which can be measured with this chloride sweat test.

Why this test is performed?

This test may be recommended to you if you experience symptoms of cystic fibrosis. The symptoms include repeated respiratory infections such as bronchitis or pneumonia, frequent coughing with thick mucus sometimes with blood, repeated sinus infections, nasal congestion, pain or discomfort, etc. The symptoms in newborns are stools produced immediately after birth, chronic diarrhea or foul-smelling, greasy stools, weight loss or malnutrition, large appetite but failure to gain weight or grow at a normal rate, etc. This test may be performed if you have a family history of cystic fibrosis. In infants, this test is recommended if the newborn screening test for cystic fibrosis is positive.

No specific preparation is required for this test.