The defective protein allows too much salt to leave the body through sweat. Very low salt levels in the body can cause heartbeat problems or shock. This happens most often in hot weather. Mucus throughout the body doesn't contain enough water. It becomes too thick and clogs the lungs and digestive tract.
Breathing becomes difficult.
Over time there is permanent lung damage from recurring bronchitis and pneumonia. Newborns with CF may often have a blocked intestine. Eventually, the thick mucus blocks the ducts of the pancreas. The pancreas produces several important enzymes for digestion. Without them, a person does not properly absorb fat, protein, and several vitamins.