Amyloidosis (am-uh-loi-DO-sis) is a rare disease that occurs when a substance called amyloid builds up in your organs. Amyloid is an abnormal protein that is usually produced in your bone marrow and can be deposited in any tissue or organ. Amyloidosis can affect different organs in different people, and there are different types of amyloid. Amyloidosis frequently affects the heart, kidneys, liver, spleen, nervous system and digestive tract. Severe amyloidosis can lead to life-threatening organ failure.
Many different proteins can lead to the formation of amyloid deposits, but only a few have been linked to significant health problems. Diagnosis of amyloidosis requires tissue biopsy. Biopsy is assessed for evidence of characteristic amyloid deposits. The tissue is treated with various stains. The most useful stain in the diagnosis of amyloid is Congo red, which, combined with polarized light, makes the amyloid proteins appear apple-green on microscopy. Also, thioflavin T stain may be used.
Less than 15% of patients display the physical characteristics typically associated with amyloidosis. Less than 1% of patients with amyloidosis have tongue enlargement in the US (Amyloidosis: Recognition, Prognosis and Conventional Therapy, American Society of Hematology). In 33-40% of amyloidosis patients, the kidney is affected in the US (Amyloidosis: Recognition, Prognosis and Conventional Therapy, American Society of Hematology)