# Complement 4d (C4d) And Complement Receptor 1 (Cr1)
> **Product code: NRX** · Class II — Moderate Risk (510(k) clearance required) · Immunology · 21 CFR 866.5820
## Classification
- **FDA Product Code:** NRX
- **Device class:** Class II — Moderate Risk (510(k) clearance required)
- **Regulation:** 21 CFR 866.5820
- **Review panel:** IM
- **Medical specialty:** Immunology
- **Submission type:** 1
- **GMP exempt:** N
- **Life sustaining:** N
- **Implant:** N
- **Third-party review:** Y
## Definition

The device is an indirect immunofluorescence assay utilizing monoclonal antibodies and flow cytometry in the quantitative determination of complement 4d (C4d) and complement receptor 1 (CR1) on the surface of erythrocytes from EDTA anti-coagulated whole blood. The C4d and CR1 results are used in a ratio as an aid in the diagnosis of systemic lupus erythematosus.

## Market data
- **Cleared 510(k) submissions:** 0
- **Registered establishments:** 0
## Source
- [FDA Device Classification](https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpcd/classification.cfm?ID=NRX)
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