The DiaSorin LIAISON® FT4 assay is an in vitro chemiluminescent immunoassay intended for the quantitative determination of free thyroxine (FT4) in human serum using the LIAISON® Analyzer. It is intended for use as an aid in the clinical assessment of thyroid status.

The DiaSorin LIAISON® Control Thyroid 1, LIAISON® Control Thyroid 2 and LIAISON® Control Thyroid 3 are intended for use as assayed quality control samples to monitor the accuracy and precision of the DiaSorin LIAISON® FT4 assay.

Device Description

The DiaSorin LIAISON® FT4 assay's method for quantitative determination of FT4 is based on the Solid Phase Antigen Linked Technique (SPALT) principle. A T4-protein-conjugate is coated on the magnetic particles (solid phase); a monoclonal antibody is linked to an isoluminol derivative (isoluminol-antibody conjugate). All assay steps and incubations are performed by the LIAISON® Analyzer.

Results are determined by a 2 point calibration conversion of the master curve to a working curve. The light signal, and hence the amount of isoluminol-antibody conjugate, is measured by a photomultiplier as relative light units (RLU) and is inversely related to FT4 concentration present in calibrators, patient samples or controls.

AI/ML Overview

Here's an analysis of the provided text regarding acceptance criteria and the study proving the device meets them:

1. Table of Acceptance Criteria and Reported Device Performance

The documents do not explicitly list formal "acceptance criteria". However, performance data is presented, which implicitly demonstrates the device's acceptable performance. For clarity, I've inferred common performance metrics for this type of device and presented the reported results.

Metric (Implicit Acceptance Criteria)	Reported Device Performance (LIAISON® FT4)
Method Comparison (Against Predicate)
Linearity (Slope)	1.0707 (95% CI: 1.03 to 1.09)
Linearity (Intercept)	-0.1211 ng/dL (95% CI: -0.17 to -0.08 ng/dL)
Correlation Coefficient (R²)	0.9633
Reference Range
95% Normal Range (Serum)	0.69 - 1.59 ng/dL (8.93 - 20.4 pmol/L)
Reproducibility/Precision (20-Day Study)
Kit Control 1 (Mean 1.02 ng/dL) - Total %CV	7.9%
Kit Control 2 (Mean 3.18 ng/dL) - Total %CV	6.9%
Kit Control 3 (Mean 6.59 ng/dL) - Total %CV	7.0%
Sample 1 (Mean 1.19 ng/dL) - Total %CV	8.0%
Sample 2 (Mean 1.90 ng/dL) - Total %CV	7.5%
Sample 3 (Mean 5.56 ng/dL) - Total %CV	7.1%
Sample 4 (Mean 5.72 ng/dL) - Total %CV	7.1%
Reproducibility/Precision (5-Day Study - Near Medical Decision Points)
Sample 1 (Hypo, Mean 0.851 ng/dL) - Total %CV	9.5%
Sample 2 (Normal, Mean 1.57 ng/dL) - Total %CV	8.6%
Sample 3 (Hyper, Mean 3.25 ng/dL) - Total %CV	7.5%
Dilution Linearity	Linear across the measuring range (0.29 - 7.7 ng/dL)
Limit of Blank (LoB)	≤ 0.06 ng/dL
Limit of Detection (LoD)	0.13 ng/dL
Limit of Quantitation (LoQ)	0.29 ng/dL
Interfering Substances	No interference observed at tested concentrations
Specificity (Cross-Reactivity)	D-T4: 100%, 3-iodo-L-Tyrosine: 0%, 3,5-diiodo-L-Tyrosine: 0%, 3,3',5,5'-tetra-iodothyroacetic acid: 0%

2. Sample Sizes Used for the Test Set and Data Provenance

Method Comparison: 201 samples.
Reference Range Determination: 130 apparently healthy adult human serum samples.
Reproducibility/Precision (20-Day Study): A coded panel of 4 frozen serum samples prepared by DiaSorin, plus 3 levels of LIAISON® Control Thyroid. Each sample/control tested 80 times (2 replicates/run, 2 runs/day, 20 days).
Reproducibility/Precision (5-Day Study): A panel of three frozen serum samples prepared by DiaSorin with FT4 concentrations near medical decision points. Each sample tested 60 times (12 replicates/run, 1 run/day, 5 days).
Dilution Linearity: One spiked sample, diluted into ten evenly spaced intervals, tested in four replicates for each dilution.
LoB/LoD/LoQ: Not explicitly stated, but typically involves multiple replicates of blank and low-concentration samples.
Interfering Substances: Not explicitly detailed, but involved testing various potential interferents.
Specificity (Cross-Reactivity): Not explicitly detailed regarding sample count, but involves specific cross-reactants.

Data Provenance:
The studies appear to be prospective, performed internally by DiaSorin Inc. (e.g., "A twenty day reproducibility/precision study was performed at DiaSorin Inc.", "An additional five day precision study was performed at DiaSorin"). The "country of origin" is implied to be the US, given the submission to the FDA by DiaSorin Inc. in Stillwater, MN.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

For an in vitro diagnostic (IVD) device like a Free Thyroxine Assay, the "ground truth" is typically established by reference methods or established laboratory practices, not by expert interpretation in the same way an imaging device might use radiologists.

Method Comparison: The comparison was made against a "commercially available immunoassay," which serves as the reference or "ground truth" for comparative performance. The specific details of how its "ground truth" was established are not provided, but it is implied to be a legally marketed, accepted method (the Roche Elecsys® FT4, K961489, is named as the predicate device).
Reference Range: Established by testing samples from "130 apparently healthy adults." These samples themselves represent the "ground truth" of a healthy population.
Reproducibility/Precision, Dilution Linearity, LoB/LoD/LoQ, Interfering Substances, Specificity: These studies rely on scientifically controlled preparations (e.g., spiked samples, controls, known concentrations) and established assay principles, rather than expert consensus on patient data.

Therefore, the concept of "number of experts" and their "qualifications" for ground truth establishment, as it might apply to image-based diagnostics, is not directly applicable here. The "ground truth" for the test set is either a comparative, legally marketed device or samples with analytically defined characteristics.

4. Adjudication Method for the Test Set

Not applicable. As described above, the "ground truth" for this type of IVD device is based on analytical measurements against a comparative method or defined standards, not on subjective interpretations requiring adjudication among experts.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance

Not applicable. This is an in vitro diagnostic (IVD) assay, not an AI-powered diagnostic imaging device that involves human readers. Therefore, an MRMC study to assess human reader improvement with AI assistance is not relevant to this submission.

6. If a standalone (i.e., algorithm only without human-in-the-loop performance) was done

This device is a standalone algorithm, in the sense that it is a fully automated immunoassay system that quantitatively determines FT4 concentration without human interpretative input on the result itself (beyond clinical interpretation of the quantitative value). The performance data presented (Method Comparison, Precision, Linearity, etc.) represents the standalone performance of the LIAISON® FT4 assay. There is no human "in the loop" for the measurement process; the LIAISON® Analyzer performs all assay steps and incubates.

7. The Type of Ground Truth Used

The ground truth used for various performance evaluations includes:

Comparative Device: For method comparison, the Roche Elecsys® FT4 Test (K961489) served as the reference.
Clinically Defined Samples: For reference range determination, samples from "apparently healthy adults" were used to establish expected values.
Analytically Defined Standards/Samples: For precision, linearity, LoB/LoD/LoQ, interfering substances, and specificity, the ground truth was established by:
- Commercial Controls: LIAISON® Control Thyroid (1, 2, 3), whose target values are established through rigorous internal procedures involving multiple analyzers and kit lots.
- Internal Panels/Spiked Samples: Frozen serum samples prepared by DiaSorin, or buffer samples spiked with known concentrations of T4 and other substances.

8. The Sample Size for the Training Set

The document describes performance studies, not a machine learning model. IVD assays like the LIAISON® FT4 are based on well-established chemical and immunological principles, not on "training sets" in the context of AI. The "training" in this context refers to the development and optimization of the assay itself and its reagents.

However, if we interpret "training set" more broadly as data used to develop and optimize the assay, rather than for final validation:

Calibrator Value Assignment: Master standards are prepared and concentrations are assigned by testing in "10 different assays against the Primary Reference Standard." Kit calibrator values are then assigned using "multiple LIAISON® analyzers with several kits calibrators over several runs." This is part of the internal development and calibration process.
Control Value Assignment: A minimum of "60 valid test results for each control" are used to establish the target value and range, using "a minimum of 3 LIAISON® Analyzers, using 2 different approved LIAISON® FT4 assay kit lots, at a minimal time period of 3 days." This data essentially "trains" the acceptable control ranges.

9. How the Ground Truth for the Training Set was Established

Again, this is not an AI model, so "training set ground truth" is interpreted in the context of IVD assay development.

Calibrator "Ground Truth": The calibrators are referenced to an "in-house Primary Reference Standard preparation." This primary standard itself would be meticulously characterized and traceable to internationally recognized standards if available, or rigorously defined internally. Concentrations are assigned via testing against this standard.
Control "Ground Truth": The target values for the LIAISON® Controls (Thyroid 1, 2, 3) are established by calculating the mean from a minimum of 60 valid test results, spanning multiple analyzers, kit lots, and days. The "ground truth" for control values is therefore derived empirically from the performance of the LIAISON® FT4 assay itself, establishing an expected range for quality control.

Summary

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121951

5.0 510(k) SUMMARY

March 25, 2013

SUBMITTED BY:

Kelly R. Sauer Regulatory Affairs Specialist DiaSorin Inc. 1951 Northwestern Avenue P.O. Box 285 Stillwater, MN 55082-0285 Phone (651) 351-5884 Fax (651) 351-5669 Email: kelly.sauer@diasorin.com

· APR 4 2013

DATE PREPARED:

NAME OF DEVICE:

Trade Name:

LIAISON® FT4 LIAISON® Control Thyroid 1 LIAISON® Control Thyroid 2 LIAISON® Control Thyroid 3

Common Names/Descriptions:

Classification Names:

Free Thyroxine Assay

Free Thyroxine Test System: Class II 21 CFR 862.1695; Clinical Chemistry (75) Quality Control Material: Class I, reserved 21 CFR 862.1660; Clinical Chemistry (75)

Product Code:

PREDICATE DEVICE:

Roche Elecsys® FT4 Reference K961489 (assav) Elecsys® PreciControl Universal Reference K090541 (control set)

DEVICE DESCRIPTION:

INTENDED USE:

The DiaSorin LIAISON® FT4 assay is an in vitro chemiluminescent immunoassay (CLIA) intended for the quantitative determination of free thyroxine (FT4) in human serum using the LIAISON® Analyzer. It is intended for use as aid in the clinical assessment of thyroid status.

CEC. JJX

Section 5

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KIT DESCRIPTION:

The LIAISON® FT4 assay's method for quantitative determination of FT4 is based on the Solid Phase Antigen Linked Technique (SPALT) principle. A T4-protein-conjugate is coated on the magnetic particles (solid phase); a monoclonal antibody is linked to an isoluminol derivative (isoluminol-antibody conjugate). All assay steps and incubations are performed by the LIAISON® Analyzer.

COMPARISON TO PREDICATE DEVICE:

The DiaSorin LIAISON FT4 assay is substantially equivalent in principle and performance to the Roche Elecsys® FT4 Test (K961489) which was FDA cleared June 11, 1996.

Table 1: Table of Assay Similarities and Differences
Characteristic	New DeviceLIAISON® FT4	Predicate DeviceRoche Elecsys® FT4 (K961489)
Intended Use	The DiaSorin LIAISON® FT4Assay is a chemiluminescentimmunoassay (CLIA) intendedfor the quantitativedetermination of free thyroxine(FT4) in human serum usingthe LIAISON® Analyzer.	Immunoassay for the in vitroquantitative determination of freethyroxine in human serum andplasma. TheelectrochemiluminescenceImmunoassay "ECLIA" isintended for use on Elecsys andcobas e immunoassayanalyzers.
Indications for Use	For use as an aid in theclinical assessment of thyroidstatus	Same
Measured Analyte	Free thyroxine	Free thyroxine
Assay Type	ChemiluminescentImmunoassay	Electrochemiluminescentimmunoassay
Calibration	Two-point verification ofstored master curve.	Same
Reagent IntegralStorage	On-board or in refrigerator@2-8°C	Same
SampleHandling/Processing	Automated	Same
Unit of Measure	ng/dL or pmol/L	Same
Reference range	Serum 0.69 - 1.59 ng/dL(8.93 -20.4 pmol/L)	Serum 0.93 - 1.70 ng/dL(12.0 - 21.9 pmol/L)
Measuring range	0.29 - 7.7 ng/dL(3.73 - 99.1 pmol/L)	0.023 - 7.77ng/dL(0.300 - 100.0 pmol/L)
Sample Matrix	Human serum	Human serum and plasma

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Sample size	50µL	15µL
Conjugate Antibody	Mouse monoclonalanti-thyroxine	Sheep polyclonal anti-thyroxine
Assay time	17 minutes	18 minutes
Open storage2-8°C	2 weeks	12 weeks
Open storageon analyzer	2 weeks	4 weeks
Calibrators	2 levels - Included in integral	2 levels - Not included with kit
Controls	3 levels	2 levels

DiaSorin LIAISON® Control Thyroid 1, LIAISON® Control Thyroid 2, LIAISON® Control Thyroid 3 and Elecsys® PreciControl Universal Similarities and Differences

Table 2: Table of Control Similarities and Differences
Characteristic	New DeviceLIAISON® Control Thyroid 1LIAISON® Control Thyroid 2LIAISON® Control Thyroid 3	Predicate DeviceElecsys® PreciControlUniversal (K090541)
Intended Use	Intended for use as qualitycontrol samples to monitor theaccuracy and precision of theDiaSorin LIAISON® FT4 assay	Intended for use as qualitycontrol of Elecsys®immunoassays on the Elecsys®and Cobas® e immunoassayanalyzers
Matrix	Human serum	Same
Reagent Format	Lyophilized	Same
Storage	Unopened store at 2-8° C untilexpiration date	Same
Levels	Three concentrations :Low, medium, high	Two concentrations :Low and high
Reagent Format	4 vials x 5.0 mL each levelEach level provided separately	2 vials x 3.0 ml each level
Handling	Reconstitue with 5.0 mLdistilled waterand allow to stand 15 minutesbefore use	Reconstitute with 3.0 mLdistilled waterand allow to stand 30 minutesbefore use.
Open Storage	Reconstituted :48 hours at 2-8° CFor longer storage periods,frozen to -20 °C	Reconstituted :On analyzer at 20-25° C up to 5hrs ; 3 days at 2-8° C;-20° C for up to 1 month

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PERFORMANCE DATA:

Method Comparison:

A total of 201 samples were tested by the LIAISON® FT4 assay and a commercially available immunoassay. The method comparison study was performed according to CLSI EP9-A2 guideline.

Passing & Bablok regression analysis was performed on the results across the range of LIAISON® FT4 assay yielding agreement of y =1.0707x - 0.1211, R2 = 0.9633. The 95% confidence intervals for the slope were 1.03 to 1.09 and 95% confidence intervals for the intercept were -0.17 to -0.08 ng/dL.

Reference Range/Expected Values:

Human serum samples from 130 apparently healthy adults were tested to determine the reference range for the LIAISON® FT4 assay.

Apparently Healthy Adults	Median	Observed 95% Normal Range
Serum (130)	1.08 ng/dL	0.69 — 1.59 ng/dL
	13.9 pmol/L	8.93 - 20.4 pmol/L
		Consider these limits as guidelines only. Each laboratory should establish its own reference range

Reproducibility/Precision:

20 Day Study Design

A twenty day reproducibility/precision study was performed at DiaSorin Inc. A coded panel comprised of 4 frozen serum samples was prepared by DiaSorin. The LIAISON® Control Thyroid (3 levels) were also tested in the study. The CLSI document EP5-A2 was consultred in the preparation of the testing protocol.

The precision panel samples and kit controls were tested on one lot of LIAISON® FT4 assay in two replicates per run, 2 runs per day for 20 operating days for a total of 80 replicate results per sample.

The mean, standard deviation, and coefficient of variation (%CV) of the results were computed for each of the tested samples.

Results:

The 20 day results are summarized in Table 3 as sample overall mean FT4 concentration in ng/dL, computed SDs and %CVs for between run and total.

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		Mean	Between Run		TOTAL
Sample	N	(ng/dL)	SD	%CV	SD	%CV
Kit Control 1	80	1.02	0.02	1.8%	0.08	7.9%
Kit Control 2	80	3.18	0.07	2.3%	0.22	6.9%
Kit Control 3	80	6.59	0.33	4.9%	0.46	7.0%
Sample 1	80	1.19	0.03	2.7%	0.09	8.0%
Sample 2	80	1.90	0.05	2.4%	0.14	7.5%
Sample 3	80	5.56	0.17	3.1%	0.40	7.1%
Sample 4	80	5.72	0.17	2.9%	0.40	7.1%

Table 3: Reproducibility/Precision Results - 20 day

5 Day Study Design

An additional five day precision study was performed at DiaSorin. The sample panel consisted of three frozen serum samples prepared by DiaSorin with FT4 concentrations near medical decision points.

The precision panel samples were tested on one lot of LIAISON® FT4 assay in twelve replicates per run, one run per day for 5 operating days for a total of 60 replicate results per sample.

Results:

The 5 day results are summarized in Table 4 as sample overall mean FT4 concentration in ng/dL, computed SDs and %CVs for between run and total.

Sample	N	Mean (ng/dL)	Between RunSD	Between Run%CV	TOTALSD	TOTAL%CV
Sample 1 (hypo)	60	0.851	0.08	9.7	0.08	9.5%
Sample 2 (normal)	60	1.57	0.14	9.0	0.13	8.6%
Sample 3 (hyper)	60	3.25	0.24	7.4	0.24	7.5%

Table 4: Reproducibility/Precision Results - 5 day

Dilution Linearity:

An aliquot of a buffer sample containing phosphate buffered saline (PBS), 5% BSA was spiked with T4 and diluted with the same buffer. This yielded a sample with T4 levels spanning the measuring range of the LIAISON® FT4 assay (0.29 - 7.7 ng/dL). The sample was analyzed by the LIAISON® FT4 assay following CLSI EP6-A. The sample was diluted into ten evenly spaced intervals including the neat sample and tested in four replicates for each dilution on the LIAISON® Analyzer.

Results:

The results were analyzed by a linear regression of measured FT4 concentration versus expected FT4. The resulting regression equation:

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LIAISON® FT4 Assay is linear across the measuring range of the assay (0.29 - 7.7 ng/dL).

Traceability, Stability, Target Values:

Traceability: The LIAISON® FT4 kit calibrators are referenced to an 'in-house'' Primary Reference Standard preparation.

Calibrator Value Assignment: Calibrator concentrations are assigned through an internal procedure. Master standards are prepared from intermediate stock solutions. Concentrations are assigned by testing in 10 different assays against the Primary Reference Standard. The master calibrators are then used to assign values to the kit calibrators using multiple LIAISON® analyzers with several kits calibrators over several runs to determine the target values.

Calibrator Stability: Reagent integral is stable until the expiration date printed on the label when stored as directed and for 2 weeks (14 days) on board the LIAISON® analyzer or opened and stored at 2-8°C.

Calibration curve stability was performed and demonstrated that kit performance was acceptable to 2 weeks from calibration.

LIAISON® FT4 Calibrator 1 is manufactured to have a FT4 level between 0.45 - 0.55 ng/dL. LIAISON® FT4 Calibrator 2 is manufactured to have a FT4 level between 5.0 – 7.0 ng/dL.

Control Value Assignment: A minimum of 60 valid test results for each control are used in the range assignment. The LIAISON® Control Thyroid 1, LIAISON® Control Thyroid 2, LIAISON® Control Thyroid 3 are tested on a minimum of 3 LIAISON® Analyzers, using 2 different approved LIAISON® FT4 assay kit lots, at a minimal time period of 3 days. The mean value and the standard deviation (std) is calculated from the test results. The target value of the controls is given by the calculated mean value. The target range is given by the mean value +/- 3 std.

Control Stability: Lyophilized controls are stable until the expiration date shown on the product labeling when stored as instructed.

Reconstituted controls are stable for up to 48 hours when stored at 2-8°C. For longer storage periods, control aliquots should be frozen to -20°C.

LIAISON® Control Thyroid 1 has a target value of 1.0 ng/dL LIAISON® Control Thyroid 2 has a target value of 3.0 ng/dL LIAISON® Control Thyroid 3 has a target value of 6.0 ng/dL

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LoB/LoD/LoQ

The Limit of Blank, Limit of Detection and Limit of Quantitation were determined according to CLSI EP17-A: Protocols for Determination of Limits of Detection and Limits of Quantitation.

The following limits were determined with the LIAISON® FT4 assay:

Limit of Blank: ≤ 0.06 nq/dL Limit of Detection: 0.13 na/dL Limit of Quantitation: 0.29 ng/dL

Interfering Substances

Controlled studies of potentially interfering substances showed no interference at the concentration for each substance listed below in the LIAISON® FT4 assay. The testing was based on CLSI-EP7-A2.

Substance/Drug	ConcentrationTested
Hemoglobin	1000 mg/dL
Triglycerides	3000 mg/dL
Bilirubin (conj)	20 mg/dL
Bilirubin (unconj)	20 mg/dL
Salicylic acid	741300 ng/dL
Acetylsalicylic acid	907200 ng/dL
Phenylbutazone	1540500 ng/dL
Diphenylhydantoin	1301397 ng/dL
Amiodarone	3396600 ng/dL
8-Anilino-1-naphtalenesulfonic acidammonium salt	1579200 ng/dL
Furosemide	1626000 ng/dL
Iopanic acid	2842000 ng/dL
DL-propranolol	1520000 ng/dL
Rheumatoid Factor	54 IU/mL

Specificity

The cross-reactivity of the LIAISON®FT4 assay with these substances has been expressed where possible as the ratio of:

The amount of the T4 required to displace 50% of the maximally bound labeled T4 from . the anti-T4 antibody,
The amount the cross-reactant to give the same 50% displacement. .

Amounts for cross-reactant and analyte are taken from the displacement curve. The ratio of the two amounts as percentage-value is the % cross-reactivity of the cross reactant.

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Cross-Reactant	% Cross-reactivity
D-T4	100%
3-iodo-L-Tyrosine	0%
3,5-diiodo-L-Tyrosine	0%
3,3',5,5'-tetra-iodothyroacetic acid	0%

CONCLUSION:

The material submitted in this premarket notification is complete and supports the basis for substantial equivalence. The labeling is sufficient and satisfies the requirements of 21 CFR Part 809.10.

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DEPARTMENT OF HEALTH & HUMAN SERVICES

Image /page/8/Picture/1 description: The image shows the logo for the U.S. Department of Health & Human Services. The logo consists of a stylized depiction of an eagle or bird-like figure with three curved lines representing its wings or body. The text "DEPARTMENT OF HEALTH & HUMAN SERVICES - USA" is arranged in a circular fashion around the bird-like figure.

Public Health Service

Food and Drug Administration 10903 New Hampshire Avenue Document Control Center - WO66-G609 Silver Spring, MD 20993-0002

April 4, 2013

KELLY R SAUER REGULATORY AFFAIRS SPECIALIST DIASORIN 1951 NORTHWESTERN AVE. P.O. BOX 285 STILLWATER MN 55082

Re: K121951

Trade/Device Name: LIAISON® FT4, LIAISON® Control Thyroid 1, LIAISON® Control Thyroid 2, LIAISON® Control Thyroid 3

Regulation Number: 21 CFR 862.1695 Regulation Name: Free thyroxine test system Regulatory Class: II Product Code: CEC, JJX Dated: March 25, 2013 Received: March 28, 2013

Dear Ms. Sauer:

We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. The general controls provisions of the Act include requirements for annual registration. Ilisting of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA). it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.

Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Parts 801 and 809); medical device reporting of medical device-related adverse events) (21 CFR 803); good manufacturing practice requirements . as set forth in the quality systems (QS) regulation (21 CFR Part 820); and if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.

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If you desire specific advice for your device on our labeling regulations (21 CFR Parts 801 and 809), please contact the Office of In Vitro Diagnostics and Radiological Health at (301) 796-5450. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21CFR Part 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to

http://www.fda.gov/MedicalDevices/Safety/ReportaProblem/default.htm for the CDRH's Office of Surveillance and Biometrics/Division of Postmarket Surveillance.

You may obtain other general information on your responsibilities under the Act from the Division of Small Manufacturers, International and Consumer Assistance at its toll-free number (800) 638-2041 or (301) 796-7100 or at its Internet address http://www.fda.gov/MedicalDevices/Resourcesfor You/Industry/default.htm.

Sincerely yours.

Carol C. Benson -S for

Courtney H. Lias, Ph.D.

Director, Division of Chemistry and Toxicology Devices Office of In Vitro Diagnostics and Radiological Health Center for Devices and Radiological Health

Enclosure

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Indications for Use

510(k) Number (if known): K121951

Device Name: LIAISON® FT4 LIAISON® Control Thyroid 1, LIAISON® Control Thyroid 2 LIAISON® Control Thyroid 3

Indications for Use:

Prescription Use X (21 CFR Part 801 Subpart D) And/Or

Over the Counter Use (21 CFR Part 801 Subpart C)

(PLEASE DO NOT WRITE BELOW THIS LINE; CONTINUE ON ANOTHER PAGE IF NEEDED)

Concurrence of CDRH, Office of In Vitro Diagnostics and Radiological Health (OIR)

YungW.DChan -S

Division Sign-Off Office of In Vitro Diagnostics and Radiological Health

510(k) K121951

Page 1 of 1

Regulation Number and Section

§ 862.1695 Free thyroxine test system.

(a)
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.(b)
Classification. Class II.