ENZYMUN-TEST FT3

K962760 · Boehringer Mannheim Corp. · CDP · Nov 29, 1996 · Clinical Chemistry

Device Facts

• Record ID: K962760
• Device Name: ENZYMUN-TEST FT3
• Applicant: Boehringer Mannheim Corp.
• Product Code: CDP · Clinical Chemistry
• Decision Date: Nov 29, 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

Enzymun-Test FT3 is an in vitro diagnostic immunoassay for measuring free triiodothyronine (FT3) in human serum or plasma. The device utilizes a competitive test principle involving polyclonal antibodies against T3 and streptavidin-coated tubes. The process involves two incubation steps: first, sample and anti-T3 antibody-POD conjugate are added to the tube; second, biotinylated T3 polyhaptens are added to bind excess conjugate to the tube wall. After a separation step to remove unbound constituents, POD activity is measured photometrically using a chromogen and H2O2 substrate. The resulting dark green cation concentration is inversely proportional to the FT3 concentration in the sample. Results are calculated via a calibration curve on the ES 300 instrument. Clinicians use these quantitative results to assess thyroid function, diagnose thyroid disorders, and monitor treatment efficacy.

Clinical Evidence

No clinical data provided. Substantial equivalence is based on analytical performance and comparison of the competitive immunoassay methodology to the predicate device.

Technological Characteristics

Competitive immunoassay; streptavidin-coated tubes; polyclonal anti-T3 antibodies; POD (peroxidase) conjugate; photometric detection; requires ES 300 instrument; serum/plasma sample matrix.

Indications for Use

Indicated for the quantitative determination of free triiodothyronine (FT3) in human serum and plasma to aid in the diagnosis and treatment of thyroid diseases, including hyperthyroidism and hypothyroidism, particularly when other tests yield borderline or conflicting results.

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

• Diagnostic Products Corp. FT3

Submission Summary (Full Text)

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NOV 29 1996 510(k) Summary
K962760

## 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: John D. Stevens
Date Prepared: July 12, 1996

### 2) Device name

Proprietary name: Enzymun-Test® FT3
Common name: free triiodothyronine test system

### 3) Predicate device

We claim substantial equivalence to the Diagnostic Products Corp. FT3.

### 4) Device Description

The Enzymun FT3 employs a competitive test principle with polyclonal antibodies directed against T3 and with streptavidin tubes.

- 1st Incubation: Sample (100 μl) and a specific anti-T3 antibody are added to the streptavidin tube and all the FT3 present in the sample binds to the anti-T3 antibody-POD conjugate.
- 2nd Incubation: Incubation buffer (biotinylated T# polyhaptens) is added and binds with excess anti-T3 antibody-POD conjugate to the wall of the streptavidin tube.

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510(k) Summary, Continued

4) Device Description, cont.

- In the separation step, serum or plasma FT3-anti-T3 antibody-POD conjugate, excess biotinylated T3 polyhaptens and serum constituents are removed.
- The activity of the POD bound to the tube wall is determined photometrically after the addition of the chromogen and the substrate H2O2 (from sodium perborate). In the indicator reaction, the chromophore formed is a dark green cation whose concentration is indirectly proportional to the FT3 concentration in the sample. Results are determined via a calibration curve.

5) Intended use

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

6) Indications for use

T3 is biologically the most important thyroid hormone and has been shown to be four to five times more potent than T4. At least 80% of T3 is derived from the deiodination of T4 by the liver and other peripheral tissues rather than from direct secretion by the thyroid.

Since T3 and T4 are poorly soluble in plasma, 70% to 75% are transported by thyroid binding globulin (TBG), a plasma protein. A very low concentration of free T3 (FT3) and free T4 (FT4) exist in equilibrium in plasma with their protein-bound counterparts. However, it is the FT3 and FT4 that are the physiologically active thyroid hormones.. Only these free hormones can bind to receptors on cell surfaces. The cell then converts FT4 to FT3 which can deliver its hormonal message by reacting with DNA.

Circulating FT3 is found in very small quantities (the ratio of FT3 to total T3 is 1:300, or about 0.3% of total serum T3). FT3 and FT4 tend to parallel changes in total T3 and T4, and are not affected by abnormal TBG concentrations.

FT3 measurements are used in the diagnosis and treatment of thyroid diseases. It should be noted that increases and decreases of FT3 and FT4 more accurately reflect hyperthyroidism and hypothyroidism. As such, FT3 is very useful when other tests reflect borderline or conflicting results.

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510(k) Summary, Continued

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 Diagnostic Products Corporation FT3.

Similarities:

- Intended use: immunoassay for the in vitro quantitative determination of free triiodothyronine (FT3)
- Competitive test principle
- Sample type and volume: serum and plasma, 100μl
- Standardization: weighed in standards

Differences:

| Feature | Enzymun FT3 | DPC FT3 |
| --- | --- | --- |
| Reaction test principle | streptavidin microparticles and electrochemiluminescence technology | solid phase radioimmunoassay technology |
| Instrument required | ES 300 | gamma counter |
| Measuring range | 0.5 to 30 pg/mL | 0.5 to 42 pg/mL |