Why Is the Level of Serum Amyloid A Elevated?

Serum Amyloid A Elevation: Causes and Clinical Significance

Elevated serum amyloid A (SAA) is an indicator of certain medical tests. Clinically, this elevation is often associated with acute inflammatory diseases. Acute infections can be caused by bacterial or viral infections, and may also be related to tumors or diseases such as lupus erythematosus. Let's briefly explore the reasons for elevated serum amyloid A.

1. Reasons for Elevated Serum Amyloid A

Amyloid A is a highly sensitive indicator for assessing acute inflammatory responses, produced by the liver. Infections caused by bacteria, viruses, and other pathogens can lead to an increase in amyloid A levels, which typically decrease rapidly after infection control. Amyloid A is also a sensitive indicator for the detection of transplant rejection and is used for diagnosing secondary amyloidosis. Additionally, amyloid A levels tend to be significantly higher during tumor metastasis compared to localized tumors.

2. What is Serum Amyloid A?

SAA is an acute-phase protein that binds to high-density lipoprotein (HDL) in the plasma. Current clinical research focuses on the types of SAA during acute inflammatory responses. Compared to the well-established acute-phase protein CRP, the advantages of SAA in the diagnosis of acute inflammatory diseases remain to be determined.

3. Clinical Significance

The response patterns of SAA and CRP are parallel during the recovery stage of acute infections, applicable to both bacterial and viral infections. SAA levels do not increase in lupus erythematosus and ulcerative colitis. Elevated SAA levels during tumor metastasis typically indicate higher values compared to those observed when the tumor is confined to a specific organ. SAA detection is a sensitive indicator for transplant rejection. In a study of kidney transplant recipients, 97% of rejection cases were detected based on SAA elevation. In cases of irreversible transplant rejection, the average concentration of SAA reached 690±29mg/L, while the corresponding level for reversible rejection episodes was 271±31mg/L. Chronically elevated SAA concentrations in patients with rheumatoid arthritis, tuberculosis, or leprosy are prerequisites for the synthesis of AA-amyloid fibers, which are also used for diagnosing secondary amyloidosis.