Health A-Z

Medical Content Created by the Faculty of the Harvard Medical School


What Is It?

Amyloidosis is a disease in which an abnormal protein called amyloid accumulates in body tissues and organs. The protein deposits can be in a single organ or dispersed throughout the body. The disease causes serious problems in the affected areas. As a result, people with amyloidosis in different body parts may experience different physical problems:

  • Brain - Dementia

  • Heart - Heart failure, an irregular or unstable heart rhythm, enlarged heart

  • Kidneys - Kidney failure, protein in the urine

  • Nervous system - Numbness, tingling or weakness from nerve disease

  • Digestive system - Intestinal bleeding, intestinal obstruction, poor nutrient absorption

  • Blood - Low blood counts, easy bruising or bleeding

  • Pancreas - Diabetes

  • Musculoskeletal system - Joint pain or swelling, weakness

  • Skin - Lumps or purple discoloration

No one knows what causes amyloidosis. To make matters more complex, amyloidosis is not a single disease, and there are many different types of amyloid protein's that can be involved. For example, Alzheimer's disease and Creutzfeldt-Jakob disease (a rare cause of dementia linked to viruses living in livestock) are two distinct conditions characterized by amyloid deposits in the brain, but the proteins involved are different.

One of the methods physicians use to categorize the type of amyloidosis is to classify it as either primary or secondary. When there is no other underlying disease, and the main problem stems from amyloidosis, the disorder is considered primary. When another disease, usually a chronic inflammatory condition such as tuberculosis or a rheumatic disease, leads to amyloidosis, the disorder is considered secondary.

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From Health A-Z, Harvard Health Publications. Copyright 2007 by the President and Fellows of Harvard College. All rights reserved. Written permission is required to reproduce, in any manner, in whole or in part, the material contained herein. To make a reprint request, contact Harvard Health Publications. Used with permission of StayWell.

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