What causes amyloid to build up excessively usually isn't known. However, amyloidosis can be a response to various diseases that cause persistent infection or inflammation. Yet another form of amyloidosis is associated with Alzheimer's disease. The accumulation of large amounts of amyloid can disturb the normal functioning of many organs. The symptoms of amyloidosis depend on where the amyloid builds up.
Many people have few symptoms, while others develop severe, life-threatening disease.
In primary amyloidosis, typical sites of amyloid buildup are the heart, lungs, skin, tongue, thyroid gland, intestines, liver, kidney, and blood vessels. This accumulation can lead to heart failure, an irregular heartbeat, difficulty in breathing, a thickened tongue, an underactive thyroid gland, poor absorption of food, liver failure, kidney failure, and easy bruising or other abnormal bleeding because of its effect on blood clotting. Nerves may malfunction, leading to weakness and abnormal sensations. Carpal tunnel syndrome may develop. When amyloid affects the heart, death may occur as a result of severe heart failure or an irregular heartbeat.