Sweat Testing for Cystic Fibrosis

For the past forty plus years, sweat testing has been the most effective, and therefore the most popular, test for detecting cystic fibrosis. However, if a person tests positive for cystic fibrosis, a repeat of the sweat test should be performed to confirm the diagnosis.

How Sweat Testing is Performed

The sweat test is performed by using an electrode filled with pilocarpine. The electrode is placed on the inner forearm, and a second electrode is placed on the outer forearm. A current is run through the electrodes delivering the pilocarpine under the skin.

Sweating testing is painless, however the person will feel a slight tingling sensation on the skin where the eletrodes are placed.

The electrodes are removed and the arm is left to rest for about a one-half hour with the filter paper. The filter paper will soak up any sweat released from the person's skin. Once the one-half hour is up, the filter paper is placed into a flask and rinsed to release the sweat from the filter.

A digital chloridometer is used to measure the concentration of chloride ions in the fluid. If more than 60 mmol/liter is detected, cystic fibrosis is diagnosed.

Quick Fact: Many, many years ago, doctors would lick babies shortly after birth to determine if they had cystic fibrosis!

Source: yourgenesyourhealth.org and irishealth.com
Created: 11/24/05