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  5. N Latex SAA Assay
COVID-19 virus next to N Latex SAA Assay bottle

N Latex SAA Assay Add sensitivity in diagnosis and monitoring of inflammatory processes

Available on Atellica NEPH 630 System
Available on Atellica NEPH 630 System

The Serum Amyloid A (SAA) Assay* for use on Atellica® NEPH 630,* BN™ II, and BN ProSpec® Systems is designed to enhance diagnostic sensitivity for infections.

Parallel determination of CRP and SAA is useful in diagnosing inflammatory processes, especially viral infections, due to a strong rise in its blood concentration within a few hours.1,2

Recent studies show that SAA can be a prognostic marker for decline and death in COVID-19 patients. 3,4,5

Features & Benefits

The Serum Amyloid A (SAA) Assay* from Siemens Healthineers provides:

  • High specificity based on monoclonal antibodies
  • Fully automated testing for improved workflow
  • A broad initial measuring range (3–200 mg/L) that helps reduce the need for redilutions and supports economical reagent use
  • A complete kit, including reagent, calibrator, controls, and supplementary reagent (SCS Cleaner reagent available separately)
  • The ability to perform parallel determination of SAA and CRP, which can enhance diagnostic sensitivity for infections 2

Clinical Use

High sensitivity in diagnosis and monitoring of inflammatory processes.

Serum amyloid A (SAA) represents a protein family and is an acute-phase protein mainly produced by the liver in response to proinflammatory cytokines secreted by the activated monocytes/macrophage lineages.

Like C-reactive protein (CRP), SAA determination can be used in the diagnosis and monitoring of inflammatory and infectious processes. In contrast to CRP, SAA levels show a stronger response to viral infections, while CRP responds more strongly to systemic bacterial infections.2

SAA plasma levels can increase up to 1000-fold, for instance, due to the effect of IL-6 in the course of a cytokine storm. First elevations are seen 3–6 hours after an inflammatory stimulus, reaching a peak concentration in 2–3 days.2,6

Mo et al. studied 118 patients with COVID‐19 (102 mild, 16 severe) for the prognostic value of the inflammation markers SAA, CRP, and PCT applying receiver operating characteristic (ROC) curve analysis, a mathematical procedure to determine the predictive value of the cutoff for a test.3

SAA clearly had the highest predictive value for disease progression of the three inflammation markers (AUC = 0.968).

Inflammatory indicators in COVID-19

Figure 1. The diagnostic value of inflammatory indicators in predicting acute aggravation of COVID‐19 (orange: SAA, grey: CRP, teal: PCT).3

SAA, as currently understood, is one of the strongest indicators of SARS-CoV-2 inflammation compared to other acute-phase proteins.

Technical Specifications

Analytical Assay Performance

Assay principle

Latex-enhanced immunonephelometry

Sample type

Human serum, heparinized plasma

Reference range

<6.4 mg/L

Initial measuring ranges

3.0–200 mg/L

Detection limit

0.8 mg/L

Measuring time

6 minutes

Onboard reagent stability

4 weeks (Atellica NEPH 630* and BN ProSpec Systems)
5 days on BN II System

Calibration frequency

1 week (lot-dependent)

Precision

Intra-assay CV ≤6.2%
Inter-assay CV ≤4.7%
Total CV ≤6.4%

*Not available for sale in the U.S.
1
Li H, et al. SAA is a biomarker to distinguish the severity and prognosis of Coronavirus Disease 2019 (COVID-19). J Infect. 2020; 80:646-55.
2
Zhang Y, Zhang J, Sheng H, et al. Acute phase reactant serum amyloid A in inflammation and other diseases. Adv Clin Chem. 2019;90:25-80.
3
Mo XN, Su ZQ, Lei CL, et al. Serum amyloid A is a predictor for prognosis of COVID-19. Respirology. 2020;25(7):764-765.
4
Cheng L, Yang JZ, Bai WH, et al. Prognostic value of serum amyloid A in patients with COVID-19 [published online ahead of print, 2020 Jul 30]. Infection. 2020;1-8
5
Zhang Y, et al. Serum amyloid A protein as a potential biomarker useful in monitoring the course of COVID-19: a retrospectively studied. doi:10.21203/rs.3.rs-19724/v1
6
Vietri L, Bennett D, Cameli P, et al. Serum amyloid A in patients with idiopathic pulmonary fibrosis. Respir Investig. 2019;57:430-4.

The products/features (mentioned herein) are not commercially available in all countries. Due to regulatory reasons their future availability cannot be guaranteed. Please contact your local Siemens Healthineers organization for further details.

Atellica, BN, BN ProSpec, and all associated marks are trademarks of Siemens Healthcare Diagnostics Inc., or its affiliates. All other trademarks and brands are the property of their respective owners.