Serum amyloid protein a

When inflammation occurs in the human body, what means can be used to diagnose and confirm it? A common indicator of inflammation in the body is the serum amyloid protein A index. Changes in the serum amyloid protein A index can be used to determine whether there is inflammation in the human body and whether it is in a normal state. The specific clinical significance of serum amyloid protein A is as follows.

Normal value:

＜10mg/L, determined by the measurement method.

Clinical significance:

Similar to CRP, it is used to assess the progress of the acute phase reaction.

SAA is a sensitive parameter. It starts to increase about 8 hours after the inflammatory response and exceeds the upper limit of the reference range earlier than CRP. However, the median value of CRP in normal people is about 10 times higher than the upper limit of the reference range.

In SAA it is only 5 times. In minor infections, such as many viral infections, elevated SAA is more common than CRP.

In infectious diseases, the absolute increase in SAA is higher than that in CRP, so SAA determination can provide better differentiation between "normal" and minimal acute phase reactions.

Usually about 2/3 of cold patients have elevated SAA, but less than 1/2 of patients also show elevated CRP.

In cases of viral infection, elevated SAA and CRP concentrations are seen in patients with adenovirus infection.

The response patterns of SAA and CRP are parallel during the recovery phase of acute infection, and this applies to both bacterial and viral infections.

SAA is not elevated in lupus erythematosus and ulcerative colitis.

SAA elevations in the metastatic stage of malignant tumors usually show higher values ​​than in the organ-confined stage.

SAA testing is a fairly sensitive indicator for transplant rejection. In a study of renal transplant recipients, 97% of the work-ups for rejection were based on elevated SAA. In the detection of irreversible transplant rejection, the average concentration reached 690±29 mg/L, while the relevant level in cases of reversible rejection episodes was 271±31 mg/L.

Chronically elevated SAA concentrations in patients with rheumatoid arthritis, tuberculosis, or leprosy are a prerequisite for the synthesis of AA-amyloid fibrils, which is also used to diagnose secondary amyloidosis.

Precautions

Currently, the few commercially available tests show variability; comparability will be improved once a SAA reference is made available from WHO (currently under development).