Description

Serum amyloid A (SAA) is an acute time-limited protein, belonging to a heterogeneous protein in the apolipoprotein family, with a relative molecular weight of about 12 kDa. In the acute time-limited response, stimulated by interleukin-6 (IL-6) and interleukin-1 (IL-1), liver cells synthesize and secrete a large amount of SAA into the blood, which rapidly rises by about 1000 times within 5-6 hours. The half-life of SAA is about 50 minutes. SAA can quickly decrease to normal level when infection sources are cleared. It can be used as a sensitive indicator reflecting the control of infection and inflammation in the body.

C-reactive protein is synthesized by hepatocytes, produced during fetal lactation, and transmitted by the non-maternal placenta. When the body is infected or the tissue is damaged, macrophages and other white blood cells are activated to produce interleukin-6 (IL-6), interleukin-1 (IL-1), and other cytokines and other mediators. These cytokines and mediators stimulate hepatocytes and epithelial cells to produce CRP after reaching the liver.

At present, elevated serum SAA has been detected in various diseases such as bacteria, virus infection, atherosclerosis, coronary heart disease, and acute transplant rejection. SAA provides a clinical auxiliary diagnosis for certain diseases, such as viral infection, transplant rejection, coronary heart disease, etc. The combined detection of SAA and CRP is helpful for the early diagnosis of neonatal sepsis and the identification of bacterial infections from viral infections. The sensitivity of SAA during viral infection is significantly higher than that of CRP, while SAA and CRP are both elevated in patients with a bacterial infection.