ELECSYS FT4 ASSAY

K961489 · Boehringer Mannheim Corp. · CEC · Jun 11, 1996 · Clinical Chemistry

Device Facts

• Record ID: K961489
• Device Name: ELECSYS FT4 ASSAY
• Applicant: Boehringer Mannheim Corp.
• Product Code: CEC · Clinical Chemistry
• Decision Date: Jun 11, 1996
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 862.1695
• Device Class: Class 2

Intended Use

Immunoassay for the in vitro quantitative determination of free thyroxine in human serum and plasma.

Device Story

Elecsys® FT4 Assay is an electrochemiluminescence immunoassay for quantitative determination of free thyroxine (FT4) in human serum and plasma. Device operates on Elecsys® 2010 instrument. Principle: competitive immunoassay; 15 μL sample incubated with ruthenium-labeled anti-T4 antibody; biotinylated T4 and streptavidin-coated microparticles added; antibody-hapten complex binds to solid phase via biotin-streptavidin interaction. Microparticles magnetically captured on electrode surface; voltage applied to induce chemiluminescence measured by photomultiplier. Results calculated via 2-point calibration and reagent bar code master curve. Used in clinical laboratory settings by trained personnel to assess thyroid function; aids in diagnosis and monitoring of thyroid disorders.

Clinical Evidence

Bench testing only. Precision evaluated using modified NCCLS protocols (N=60 per level); within-run %CV 1.58%, total %CV 3.54%. Sensitivity (lower detection limit) 0.023 ng/dL. Method comparison against predicate (N=315) showed correlation r=0.981. Specificity evaluated via cross-reactivity testing against T3 and tyrosine derivatives. Interference testing performed for bilirubin, hemoglobin, lipemia, and biotin.

Technological Characteristics

Electrochemiluminescence immunoassay; ruthenium complex label; streptavidin-coated microparticles; biotinylated T4; polyclonal sheep anti-FT4 antibodies. Requires Elecsys® 2010 instrument. Calibration via 2-point method and reagent bar code. Assay duration 18 minutes at 37°C.

Indications for Use

Indicated for the in vitro quantitative determination of free thyroxine in human serum and plasma for clinical diagnostic purposes.

Regulatory Classification

Identification

A free thyroxine test system is a device intended to measure free (not protein bound) thyroxine (thyroid hormone) in serum or plasma. Levels of free thyroxine in plasma are thought to reflect the amount of thyroxine hormone available to the cells and may therefore determine the clinical metabolic status of thyroxine. Measurements obtained by this device are used in the diagnosis and treatment of thyroid diseases.

Predicate Devices

• Enzymun-Test® FT4 (K900883)

Submission Summary (Full Text)

{0}

K90489
Diagnostics

JUN | | 1996
510(k) Summary

Introduction
According to the requirements of 21 CFR 807.92, the following information provides sufficient detail to understand the basis for a determination of substantial equivalence.

1. Submitter name, address, contact
Boehringer Mannheim Corporation
2400 Bisso Lane
Concord, CA 94524-4117
[phone]; extension 8240
Contact Person: Betsy Soares-Maddox
Date Prepared: April 9, 1996

2. Device name
Proprietary name: Elecsys® FT4 Assay
Common name: Electrochemiluminescence assay for the determination of free thyroxine (FT4).
Classification name: Radioimmunoassay, Free Thyroxine

3. Predicate device
We claim substantial equivalence to the Enzymun-Test® FT4 (K900883)

4. Device Description
The Elecsys® test principle is based on competition principle. Total duration of assay: 18 minutes (37° C).
- 1st incubation (9 minutes): Sample (15 μL) and a specific anti-T4 antibody labeled with a ruthenium complex (75 μL).
- 2nd incubation (9 minutes): After addition of biotinylated T4 (75 μL) and streptavidin-coated microparticles (35 μL), the still-free binding sites of the labeled antibody become occupied, with formation of an antibody-hapten complex. The entire complex is bound to the solid phase via interaction of biotin and streptavidin.

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Diagnostics

# 510(k) Summary, Continued

4. Device Description, cont.
- The reaction mixture is aspirated into the measuring cell where the microparticles are magnetically captured onto the surface of the electrode. Unbound substances are then removed with ProCell. Application of a voltage to the electrode then induces chemiluminescent emission which is measured by a photomultiplier (0.4 second read frame).
- Results are determined via a calibration curve which is instrument-specifically generated by 2-point calibration and a master curve provided via the reagent bar code.

5. Intended use
Immunoassay for the in vitro quantitative determination of free thyroxine in human serum and plasma.

6. Comparison to predicate device
The Boehringer Mannheim Elecsys® FT4 is substantially equivalent to other products in commercial distribution intended for similar use. Most notably it is substantially equivalent to the currently marketed Enzymun-Test® FT4 (K900883).

The following table compares the Elecsys® FT4 with the predicate device, Enzymun-Test® FT4. Specific data on the performance of the test have been incorporated into the draft labeling in attachment 5. Labeling for the predicate device is provided in attachment 6.

## Similarities:
- Intended Use: Immunoassay for the in vitro quantitative determination of free thyroxine
- Sample type: Serum and plasma
- Antibody: Polyclonal Sheep anti-FT4 antibodies
- Solid phase binding principle: Streptavidin/Biotin
- Assay standardization: Equilibrium dialysis

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Diagnostics

# 510(k) Summary, Continued

## 6. Comparison to predicate device cont.

### Differences:

| Feature | Elecsys® FT4 | Enzymun-Test® FT4 |
| --- | --- | --- |
| Reaction test principle | Electrochemiluminescence | ELISA/1-step sandwich assay using streptavidin technology |
| Instrument required | Elecsys® 2010 | ES 300 |
| Assay Range | Reportable Range: 0.023 ng/dL - 7.77 ng/dL (0.3 - 100.0 pmol/L) | Reportable Range: 0.1 ng/dL - 6.5 ng/dL (1.29 - 83.69 pmol/L) |
| Calibration Stability | A calibration is recommended every 7 days if kit is not consumed; 4 weeks with same reagent lot if reagent is consumed within 7 days. | A calibration is required every 2 weeks. |

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Diagnostics

# 510(k) Summary, Continued

## 6. Comparison to predicate device, (cont.)

### Performance Characteristics:

| Feature | Elecsys® FT4 | | | Enzymun-Test® FT4 | | |
| --- | --- | --- | --- | --- | --- | --- |
| Precision | Modified NCCLS (pmol/L): | | | Modified NCCLS (ng/dL): | | |
| Level | Sample | Control 1 | Control 2 | Low | Mid | High |
| N | 60 | 60 | 60 | 117 | 120 | 120 |
| Within-Run | 8.77 | 17.53 | 50.84 | 0.49 | 1.17 | 4.43 |
| %CV | 1.58 | 1.43 | 2.85 | 3.9 | 2.4 | 1.2 |
| Total | 8.77 | 17.53 | 50.84 | 0.49 | 1.17 | 4.43 |
| %CV | 3.54 | 2.72 | 6.59 | 5.1 | 2.9 | 2.0 |
| | Modified NCCLS (ng/dL): | | | | | |
| | Sample | Control 1 | Control 2 | | | |
| N | 60 | 60 | 60 | | | |
| Within-Run | 0.684 | 1.367 | 3.97 | | | |
| %CV | 1.58 | 1.43 | 2.85 | | | |
| Total | 0.684 | 1.367 | 3.97 | | | |
| %CV | 3.54 | 2.72 | 2.85 | | | |
| Sensitivity | Lower Detection Limit: 0.023 ng/dL (0.3 pmol/L) | | | Lower Detection Limit: 0.1 ng/dL (1.29 pmol/L) | | |
| Method Comparison | Vs Enzymun-Test® FT4 Least Squares
y = 0.954x + 0.18
r = 0.981
SEE = 1.11
N = 315

Passing/Bablok
y = 1.02x + 0.36
r = 0.981
SEE = 1.11
N = 315 | | | Vs Enzymun-Test® FT4 Least Squares
y = 0.88x + 0.15
r = 0.984
SEE = 0.199
N = 77 | | |

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Diagnostics

# 510(k) Summary, Continued

## 6. Comparison to predicate device, (cont.)

Performance Characteristics, cont.:

| Feature | Elecsys® FT4 | Enzymun-Test® FT4 |
| --- | --- | --- |
| Interfering substances | No interference at: | No interference at: |
| Bilirubin | 25 mg/dL | 64.5 mg/dL |
| Hemoglobin | 1 g/dL | 1 g/dL |
| Lipemia | 1500 mg/dL | 1250 mg/dL |
| Biotin | 30 ng/mL | 200 ng/mL |
| Specificity | % Cross-reactivity | % Cross-reactivity |
| L-T4 | 100 | 100 |
| D-T4 | 100 | 100 |
| L-T3 | 1.53 | 3.5 |
| D-T3 | 1.38 | 2.9 |
| 3-iodo-L-tyrosine | 0.002 | <0.1 |
| 3,5-diiodo-L-tyrosine | 0.01 | <0.1 |
| Tetraiodo-thyroacetic acid | 38.5 | 20 |

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