ELECSYS FT3

K963127 · Boehringer Mannheim Corp. · CDP · Dec 16, 1996 · Clinical Chemistry

Device Facts

• Record ID: K963127
• Device Name: ELECSYS FT3
• Applicant: Boehringer Mannheim Corp.
• Product Code: CDP · Clinical Chemistry
• Decision Date: Dec 16, 1996
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 862.1710
• Device Class: Class 2

Intended Use

For the in vitro quantitative determination of free triiodothyronine (FT3) in human serum and plasma.

Device Story

Elecsys FT3 is an in vitro diagnostic immunoassay for measuring free triiodothyronine (FT3) in human serum and plasma. The device uses a competitive test principle involving polyclonal anti-T3 antibodies labeled with a ruthenium complex, biotinylated T3, and streptavidin-coated microparticles. The assay is performed on the Elecsys 2010 instrument. During operation, the sample and labeled antibody are incubated; biotinylated T3 and microparticles are added to form an antibody-hapten complex bound to the solid phase. The mixture is aspirated into a measuring cell where microparticles are magnetically captured on an electrode. Application of voltage induces electrochemiluminescence, which is measured by a photomultiplier. Results are calculated via a calibration curve generated by 2-point calibration and a master curve provided by reagent bar codes. The device provides clinicians with quantitative FT3 levels, which are independent of binding protein concentrations, to aid in thyroid function assessment and the differentiation of thyroid states.

Clinical Evidence

Bench testing only. Precision evaluated using NCCLS EP5-T2 (N=60 per sample, total %CV 2.7-4.7%). Sensitivity (Lower Detection Limit) reported as 0.40 pmol/l. Method comparison against predicate (N=298, r=0.94) and reference equilibrium dialysis (N=22, r=0.998). Interference testing performed for hemoglobin, lipemia, bilirubin, and biotin. Specificity cross-reactivity data provided for various thyroid-related compounds.

Technological Characteristics

Competitive immunoassay using streptavidin-coated microparticles and electrochemiluminescence detection. Requires Elecsys 2010 instrument. Reagents include ruthenium-labeled anti-T3 antibody and biotinylated T3. Calibration via 2-point method and master curve bar code. Sample volume: 30 μl.

Indications for Use

Indicated for the quantitative determination of free triiodothyronine (FT3) in human serum and plasma to assist in the diagnostic differentiation of euthyroid, hyperthyroid, and hypothyroid states.

Regulatory Classification

Identification

A total triiodothyronine test system is a device intended to measure the hormone triiodothyronine in serum and plasma. Measurements obtained by this device are used in the diagnosis and treatment of thyroid diseases such as hyperthyroidism.

Predicate Devices

• Enzymun-Test® FT3

Reference Devices

• Elkins Equilibrium Dialysis

Submission Summary (Full Text)

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K963127

510(k) Summary

DEC 16 1996

#

## 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
9115 Hague Rd.
Indianapolis, IN 46250
[phone]

Contact Person: LeeAnn Chambers
Date Prepared: August 9, 1996

## 2) Device name

Proprietary name: Elecsys® FT3
Common name: free triiodothyronine test system

## 3) Predicate device

We claim substantial equivalence to the Enzymun-Test® FT3.

## 4) Device Description

The Elecsys FT3 employs a competitive test principle with polyclonal antibodies directed against T3 and with streptavidin microparticles and electrochemiluminescence detection.

- 1st Incubation: Sample (30 μl) and a specific anti-T3 antibody labeled with a ruthenium complex.
- 2nd Incubation: After addition of biotinylated T3 and streptavidin-coated microparticles, 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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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.
- 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
For the in vitro quantitative determination of free triiodothyronine (FT3) in human serum and plasma.

5) Indications for use
Triiodothyronine is one of the thyroid hormones present in serum which regulate metabolism. Determination of this hormone concentration is important for the diagnostic differentiation of euthyroid, hyperthyroid and hypothyroid states. The major fraction of total triiodothyronine is bound to the transport proteins (TBG, prealbumin, albumin). The free triiodothyronine (fT3) is the physiologically active form of the thyroid hormone triiodothyronine.

The determination of free T3 has the advantage of being independent of changes in the concentrations and binding properties of the binding proteins; additional determination of a binding parameter of thyroxine-binding globulin (T-uptake, TBG) is therefore unnecessary. $^{1,2,3}$

The sequential testing procedure and the use of a labeled antibody reduces the possibility of interference due to altered binding properties of the serum, as can occur with assays employing labeled antigen (analog method). $^{4,5}$

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510(k) Summary, Continued

5) Indications for use, (cont.)
A variety of methods are available for estimating the free thyroid hormone levels. The direct measurement of fT4 and fT3 via equilibrium dialysis or ultrafiltration is mainly used as a reference method for standardizing the immunological procedures generally used for routine diagnostic purposes.⁴

References
1. Wheeler MH, Lazarus JH. Diseases of the Thyroid. Chapman and Hall Medical. London Glasgow Weinheim New York Tokyo Melbourne Madras 1994;107-115.
2. Pfannenstiel P, Saller B. Schilddrüsenkrankheiten Diagnose und Therapie. Berliner Medizinische Verlagsanstalt GmbH 1995; 2:30-32,60-62.
3. Fisher DA. Physiological variations in thyroid hormones physiological and pathophysiological considerations. Clinical Chemistry 1996;42:135-139.
4. Klee GG. Clinical usage recommendations and analytic performance goals for total and free triiodothyronine measurements. Clinical Chemistry 1996;42:155-159.
5. Wild D. The Immunoassay Handbook. Stockton Press 1994; 338

6) Comparison to predicate device
The Boehringer Mannheim Elecsys FT3 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® FT3.

Similarities:
- Intended use: immunoassay for the in vitro quantitative determination of free triiodothyronine (FT3)
- Competitive test principle
- Sample type: serum and plasma
- Antibody: sheep anti-T3 polyclonal
- Capture principle: streptavidin / biotin

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510(k) Summary, Continued

F. Substantial equivalence, cont.

Differences:

| Feature | Elecsys FT3 | Enzymun-Test FT3 |
| --- | --- | --- |
| Reaction test principle | streptavidin microparticles and electrochemiluminescence technology | streptavidin-coated tubes and enzyme immunoassay technology |
| Sample volume | 30 μl | 100 μl |
| Instrument required | Elecsys 2010 | ES 300 |
| Calibration | a two point calibration renewal is recommended every 7 days or 1 month if the same reagent lot is used and the reagent pack is consumed within 7 days | a full calibration curve run is recommended every 2 weeks |

Performance Characteristics:

| Feature | Elecsys FT3 | | | | | Enzymun-Test FT3 | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Precision | NCCLS (Modified) (EP5-T2) | | | | | NCCLS “Midi” (EP5-T) | | |
| Sample | PC U1* | PC U2* | HS1 | HS2 | HS3 | 1 | 2 | 3 |
| N | 60 | 60 | 60 | 60 | 60 | 120 | 120 | 120 |
| Mean | 7.64 | 20.8 | 5.11 | 10.5 | 14.4 | 2.71 | 7.86 | 28.97 |
| wi/in run %CV | 2.0 | 2.5 | 2.3 | 2.1 | 2.3 | 3.8 | 2.3 | 2.7 |
| total run %CV | 3.6 | 3.3 | 4.7 | 3.1 | 2.7 | 4.5 | 2.4 | 3.1 |
| Sensitivity | Lower Detection Limit: | | | | | Lower Detection Limit: | | |
| | 0.40 pmol/l | | | | | 0.47 pmol/l | | |
| | 0.26 pg/ml | | | | | 0.5 pg/ml | | |
| Assay range (LDL to highest standard) | 0.40 - 50 pmol/l | | | | | 0.47 - 46 pmol/l | | |
| | 0.26 - 32 pg/ml | | | | | 0.5 - 30 pg/ml | | |

* PC U1 and PC U2 = PreciControl Universal 1 and 2

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510(k) Summary, Continued

F. Substantial equivalence, contr.

| Method Comparison | vs. Enzymun-Test FT3
Least Squares
N = 298
y = -0.22 + 0.90x
r = 0.94

Passing/Bablok
N = 298
y = -1.45 + 1.06x
r = 0.94 | vs. Elkins Equilibrium Dialysis
Least Squares
N = 22
y = 0.99x +0.203
r = 0.998 |
| --- | --- | --- |
| Interfering substance:
Hemoglobin
Lipemia
Bilirubin
Biotin | No interference up to:
1 g/dl
1500 mg/dl
25 mg/dl
30 ng/ml | No interference up to:
1 g/dl
1250 mg/dl
17 mg/dl
30 ng/ml |
| Specificity
D-T3
L-T4
D-T4
L-rT3
3,3',5-tri-iodothyroacetic acid
3,3',5,5'-tetra-iodothyroacetic acid | % cross reaction
98.86
0.115
0.115
0.007
106.4
0.007 | % cross reaction
140
0.16
0.07
0.04
7.5
0.01 |