Key Information
Why is it called AA amyloidosis?
In the past, AA amyloidosis was referred to as "Secondary" or "Inflammatory" amyloidosis. These are no longer accepted names for this form of amyloidosis, which is usually caused by a complication of chronic inflammation or chronic infection. If a patient has chronic inflammation or chronic infection due to a number of possible conditions or diseases, this inflammation can often trigger an increased production of the SAA (Serum Amyloid A) protein in the body. When inflammation goes on for a very long period of time, a small portion of the SAA protein, called AA protein, will separate from SAA. This AA amyloid protein can then misfold, causing amyloid fibrils that clog and interfere with tissue and organ function.
Since systemic amyloidoses are referred to with a capital A (for amyloid) followed by an abbreviation for the fibril protein, the second "A" in AA amyloidosis stands for the fragment AA protein of Serum Amyloid A (SAA).
What is SAA protein?
SAA stands for Serum Amyloid A protein. The progression and severity of AA amyloidosis relates to the production and quantity of the SAA protein that is produced in that patient. One medical dictionary definition defines it as: "A high-molecular-weight protein synthesized in the liver; it is an acute phase protein and circulates in association with HDL lipoprotein. It is the precursor to AA amyloid and accumulates in inflammation."
In simpler terms, even though SAA is mainly produced in the liver, it circulates in the blood and is composed of different forms of proteins. These different forms of proteins assume several roles in the body, including carrying cholesterol to some organs and signaling germ-fighting cells (immune cells) to travel to areas of infection or inflammation. Therefore, an increase in SAA protein in the body is often a response to a disease or condition.