ELECSYS T-UPTAKE ASSAY

K961488 · Boehringer Mannheim Corp. · KHQ · Jun 12, 1996 · Clinical Chemistry

Device Facts

• Record ID: K961488
• Device Name: ELECSYS T-UPTAKE ASSAY
• Applicant: Boehringer Mannheim Corp.
• Product Code: KHQ · Clinical Chemistry
• Decision Date: Jun 12, 1996
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 862.1715
• Device Class: Class 2

Intended Use

Immunoassay for the in vitro quantitative determination of thyroxine-binding capacity in human serum and plasma.

Device Story

Elecsys® T-Uptake Assay is an electrochemiluminescence immunoassay for quantitative determination of thyroxine-binding capacity in human serum and plasma. Performed on the Elecsys® 2010 instrument, the assay uses a competitive principle. Sample, exogenous T4, and biotinylated T4-polyhapten are incubated; a ruthenium-labeled anti-T4 antibody is added to form a complex inversely proportional to exogenous T4 concentration. This complex binds to streptavidin-coated microparticles. Microparticles are magnetically captured on an electrode; voltage application induces chemiluminescent emission measured by a photomultiplier. Results are calculated via a 2-point calibration curve and master curve from reagent bar codes. Used in clinical laboratory settings by trained technicians to assist in thyroid function assessment.

Clinical Evidence

Bench testing only. Precision evaluated using modified NCCLS protocols (N=60 per level); within-run %CV ranged 2.15-3.29%, total %CV 2.66-3.68%. Linearity established from 0.2 to 1.9 TBI. Method comparison against Enzymun-Test® TBK (N=319) showed correlation (r=0.908, y=0.99x-0.03). Interference testing performed for bilirubin, hemoglobin, lipemia, and biotin. Specificity evaluated via cross-reactivity studies with T4/T3 analogs.

Technological Characteristics

Electrochemiluminescence immunoassay; streptavidin-coated microparticles; sheep polyclonal anti-T-Uptake antibody; ruthenium complex label. Requires Elecsys® 2010 instrument. Calibration via 2-point method and reagent bar code master curve. Solid-phase binding principle.

Indications for Use

Indicated for the in vitro quantitative determination of thyroxine-binding capacity in human serum and plasma to assess thyroid function.

Regulatory Classification

Identification

A triiodothyronine uptake test system is a device intended to measure the total amount of binding sites available for binding thyroid hormone on the thyroxine-binding proteins, thyroid-binding globulin, thyroxine-binding prealbumin, and albumin of serum and plasma. The device provides an indirect measurement of thyrkoxine levels in serum and plasma. Measurements of triiodothyronine uptake are used in the diagnosis and treatment of thyroid disorders.

Predicate Devices

• Enzymun-Test® TBK (T4 Uptake)

Submission Summary (Full Text)

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K961488
Diagnostics

JUN 12 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
P.O. Box 4117
Concord, CA 94520-4117
(510) 674 - 0690, extension 8415
Contact Person: Mary Koning
Date Prepared: April 9, 1996

2. Device name
Proprietary name: Elecsys® T-Uptake Assay
Common name: Electrochemiluminescence assay for the thyroxine-binding capacity (T-Uptake).
Classification name: Thyroxine-binding globulin test system

3. Predicate device
We claim substantial equivalence to the Enzymun-Test® TBK (T4 Uptake)

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), exogenous T4, and biotinylated T4-polyhapten (75 μL).
• 2nd incubation (9 minutes): After addition of a specific anti-T4 antibody labeled with a ruthenium complex (75 μL), the polyhapten and the antibody derivative react to form a complex, the concentration of which is inversely proportional to the concentration of the excess, exogenous T4. This immunological complex is bound to the added streptavidin-coated microparticles (35 μL) via the 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 thyroxine-binding capacity in human serum and plasma.

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510(k) Summary, Continued

6. Comparison to predicate device

The Boehringer Mannheim Elecsys® T-Uptake Assay 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® TBK (T4 Uptake).

The following table compares the Elecsys® T-Uptake with the predicate device, Enzymun-Test® TBK (T4 Uptake). 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:
- Detection of Thyroxine-Binding Capacity (T-Uptake)
- Sample type: Serum and plasma
- Reportable range of 0.2 - 1.9 TBI
- Standardized according to Enzymun-Test® TBK Assay
- Polyclonal Antibody: Sheep polyclonal anti-T-Uptake
- Solid phase binding principle: Streptavidin/Biotin

Differences:

| Feature | Elecsys® T Uptake | Enzymun-Test® TBK |
| --- | --- | --- |
| Reaction test principle | Electrochemiluminescence | ELISA/1-step sandwich assay using streptavidin technology |
| Instrument required | Elecsys® 2010 | ES 300 |
| 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. | Calibration required every run |

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510(k) Summary, Continued

6. Comparison to predicate device, (cont.)

Performance Characteristics:

| Feature | Elecsys® T Uptake | | | Enzymun-Test® TBK | | |
| --- | --- | --- | --- | --- | --- | --- |
| Precision | Modified NCCLS (TBI): | | | Modified NCCLS (TBI): | | |
| Level | Sample | Control 1 | Control 2 | Low | Mid | High |
| N | 60 | 60 | 60 | 118 | 120 | 119 |
| Within-Run | 0.95 | 0.94 | 1.09 | 0.61 | 0.93 | 1.28 |
| %CV | 2.15 | 3.29 | 2.39 | 5.7 | 2.6 | 1.4 |
| Total | 0.95 | 0.94 | 1.09 | 0.61 | 0.93 | 1.28 |
| %CV | 3.25 | 3.68 | 2.66 | 7.2 | 3.4 | 2.0 |
| Lower Detection Limit | 0.2 TBI | | | 0.2 TBI | | |
| Linearity | 0.2 TBI to the value of the highest standard | | | 0.2 TBI to the value of the highest standard | | |
| Method Comparison | Vs Enzymun-Test® TBK Least Squares | | | Vs Enzymun-Test® TBK Least Squares | | |
| | y =0.99x - 0.03 | | | y = 1.02x + 0.084 | | |
| | r=0.908 | | | r= 0.986 | | |
| | SEE =0.04 | | | SEE = 0.054 | | |
| | N=319 | | | N= 52 | | |
| | Passing/Bablok | | | | | |
| | y = 1.07x - 0.12 | | | | | |
| | r=0.908 | | | | | |
| | SEE =0.04 | | | | | |
| | N=319 | | | | | |
| | | | | | | |
| | | | | | | |

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Diagnostics

# 510(k) Summary, Continued

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

Performance Characteristics, cont.:

| Feature | Elecsys® T Uptake | Enzymun-Test® TBK |
| --- | --- | --- |
| 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 | 1.5 | 3.5 |
| D-T3 | 1.4 | 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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