The device is placed on the skin directly over the area of stimulation. Sweat is then forced through the central hole by hydrostatic pressure and is collected in the microbore tubing. After a 30 minute collection period, the tubing is detached and the sweat is extracted into a collection cup. Sweat chloride is measured using a chloridometer. It is crucial that sweat testing be carried out by qualified, experienced personnel in accordance with the National Committee for Clinical Laboratory Standards.
CF is present at birth.
However, the symptoms caused by CF may not be noticed for many years. Each individual with CF may not experience all known symptoms. The age at which people first experience symptoms varies greatly from person to person. Some people may not show any symptoms of there disease until adolescence or even into their adult years. Most people have a enough problems that they are diagnosed within the first three years of life.