CHIRON DIAGNOSTICS ACS:180TU P

K970539 · Chiron Diagnostics Corp. · KHQ · Mar 24, 1997 · Clinical Chemistry

Device Facts

• Record ID: K970539
• Device Name: CHIRON DIAGNOSTICS ACS:180TU P
• Applicant: Chiron Diagnostics Corp.
• Product Code: KHQ · Clinical Chemistry
• Decision Date: Mar 24, 1997
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 862.1715
• Device Class: Class 2

Intended Use

For the assessment of unsaturated thyroid binding proteins in serum or plasma using the Chiron Diagnostics ACS:180® Automated Chemiluminescence Systems.

Device Story

The ACS:180 TUp is an automated in vitro diagnostic assay used on the Chiron Diagnostics ACS:180 system. It measures unsaturated thyroid-binding proteins (TBG, TBPA, albumin) in serum or plasma. The assay uses a double-antibody competitive immunoassay principle with chemiluminescent detection. Samples are incubated with acridinium ester-labeled T3-BGG and unlabeled T3; these compete for monoclonal mouse anti-T3 antibody bound to paramagnetic particles. The system detects light emission, which is proportional to the amount of unsaturated binding proteins. Results are used to calculate the Free Thyroxine Index (FTI) to estimate free T4 levels. The device is intended for use in clinical laboratories by trained personnel. It assists clinicians in diagnosing thyroid conditions by compensating for abnormal binding protein levels.

Clinical Evidence

Bench testing only. Precision evaluated with 72 replicates per sample (n=3 samples) over 3 days, yielding total CVs of 4.9-6.2%. Method comparison performed on 245 samples against an alternate chemiluminescent method, showing a correlation of 0.95 for T Uptake ratios and 0.97 for FTI values. Reference range established using 100 apparently healthy individuals.

Technological Characteristics

Double antibody competitive immunoassay; chemiluminescent detection using acridinium ester labels; paramagnetic particle solid phase; monoclonal mouse anti-T3 antibody; goat anti-mouse antibody; bovine gamma globulin (BGG). Automated system platform.

Indications for Use

Indicated for the assessment of unsaturated thyroid binding proteins in serum or plasma to estimate circulating free T4 levels in patients, aiding in the evaluation of thyroid status.

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

• ACS:180 TU Assay (K925257)

Submission Summary (Full Text)

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K970539

# Summary of Safety and Effectiveness

MAR 24 1997

As required by 21 CFR 807.92, the following 510(k) Summary is provided:

## 1. Submitters Information

Contact person: William J. Pignato
Director of Regulatory Affairs

Address: Chiron Diagnostics Corporation
63 North Street
Medfield, MA 02052

Phone: [phone]

Date Summary Prepared: February 10, 1997

## 2. Device Information

Proprietary Name: Chiron Diagnostics ACS:180 TUp
Common Name: Triiodothyronine uptake test system
Device Classification: Class II, 21 CFR 862.1715

## 3. Predicate Device Information

Name: ACS:180 TU Assay
Manufacturer: Chiron Diagnostics Corporation (Formally Ciba Corning Diagnostics Corp.)
Document Control #: K925257

## 4. Device Description

The thyroid hormones triiodothyronine (T3) and thyroxine (T4) are bound primarily to thyroxine-binding globulin (TBG) and to a lesser extent thyroxine-binding prealbumin (TBPA) and albumin. The ACS:180 T Uptake assay measures the number of unoccupied binding sites on these proteins and is an indirect indicator of thyroid status.

T Uptake (TU) and total T4 are used to estimate the amount of circulating free T4. The estimate, or the Free Thyroxine Index (FTI), is a normalized measurement that remains relatively constant in healthy individuals and compensates for abnormal levels of binding proteins, which can occur in many different physical conditions.

Drugs or physical conditions that alter the patient's TBG levels or drugs that compete with endogenous T4 and T3 for protein-binding sites alter T Uptake results.

Chiron Diagnostics ACS:180 TUp
February 10, 1997
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When serum contains high levels of T3 or T4, as in hyperthyroidism, fewer unoccupied binding sites are available. Conversely, in hypothyroidism, more binding sites are available.

## 5. Statement of Intended Use

For the assessment of unsaturated thyroid binding proteins in serum or plasma using the Chiron Diagnostics ACS:180® Automated Chemiluminescence Systems.

## 6. Summary of Technological Characteristics

The Chiron Diagnostics ACS:180 TUp assay is a double antibody competitive immunoassay using, chemiluminescent technology. The sample is incubated with Lite Reagent, which is composed of acridinium ester-labeled T3-BGG (bovine gamma globulin) and unlabeled T3. The unlabeled T3 in the Lite Reagent fills available thyroid-binding sites in the sample. The acridinium ester-labeled T3-BGG does not bind to the binding proteins in the sample.

The acridinium ester-labeled T3-BGG and unlabeled T3 compete for monoclonal mouse anti-T3 antibody in the Solid Phase. The monoclonal mouse anti-T3 antibody is bound to goat anti-mouse antibody, which is covalently coupled to paramagnetic particles in the Solid Phase. A greater amount of unlabeled T3 binding to the binding proteins in the sample results in more T3-BGG-acridinium ester binding to the monoclonal antibody, an indication of a higher amount of unsaturated binding proteins.

## 6. Performance Characteristics

### Expected Results

To confirm the ACS:180 TUp serum reference range, serum samples from 100 apparently healthy individuals were analyzed. Total T4 values were generated on all of these samples using the ACS:180 T4 test method. Based on a 95% confidence interval for euthyroid samples, the following reference range was established:

| Clinical Condition | TU Ratio | % TU | FTI |
| --- | --- | --- | --- |
| Euthyroid | 0.75–1.23 | 22.5–37.0 | 1.4–3.1 |

As with all diagnostic assays, each laboratory should determine its own reference range(s) for the diagnostic evaluation of patient results.

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February 10, 1997
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# Performance Characteristics

## Specificity

The specificity of the T3 antiserum used in the ACS:180 TUp assay has been determined in the ACS:180 T3 assay.

| Compound | % Cross-reactivity |
| --- | --- |
| L-thyroxine | <0.1 |
| 3,3',5-triiodothyroacetic acid | ~25 |
| 3,5-diiodothyronine | <0.1 |
| 3,3',5'-triiodothyronine (reverse T3) | 0.6 (by weight) |
| Thyroid hormone analogues | |
| 3-iodo-L-tyrosine | <0.05 (by weight) |
| 3,5-diiodo-L-tyrosine | <0.05 (by weight) |

## Method Comparison

For 245 samples with T Uptake ratios in the range of 0.57 to 1.68 (17.1 to 50.4% Uptake) and total T4 values in the range of 3.7 to 14.1 µg/dL (47.73 to 181.89 nmol/L), the correlation between the ACS:180 TUp assay and an alternate chemiluminescent method is 0.95.

The correlation of FTI values (n = 245) is described by the following equation:

ACS:180 TUp FTI = 1.07 (alternate chemiluminescent method) + 0.04

FTI Correlation coefficient (r) = 0.97

## Precision

Three samples were assayed 3 times in 6 assays, on each of 4 systems (n = 72 for each sample), over a period of 3 days. Total precision (% CV) ranged from 4.9 to 6.2.

Chiron Diagnostics ACS:180 TUp
February 10, 1997
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