Affects all systems of the body
- Abnormally thick,
- sticky mucus, which clogs the lungs and leads to recurring lung and sinus infections as well as difficulty breathing. Reduced oxygen in the blood also leads to a characteristic rounding and enlargement of the nail bed in the fingers and toes, called clubbing. Those with the disease may also develop a barrel-shaped chest as a result of their increased work to breathe. Repeated infections often lead to fleshy growths inside the nose, called nasal polyps.
The thick mucus also obstructs the ducts of the pancreas, preventing digestive enzymes from reaching the intestines. So those with CF do not absorb nutrients from their food well, and they eliminate nondigested food through the bowel, resulting in very large, smelly stools. Because so little food is absorbed, children with CF have difficulty gaining and maintaining weight, despite a healthy appetite and diet.
CF also affects the reproductive systems of both males and females. Although females with CF have normal fallopian tubes and ovaries, their thick cervical secretions may block sperm entry and prevent them from getting pregnant. Males with CF are almost always sterile because they produce relatively few or no sperm. Abnormally thick secretions may block the ducts that carry sperm, or the ducts may not develop properly.