Measurements of alkaline phosphatase or its isoenzymes are to be used as an aid in the diagnosis and treatment of liver, bone, parathyroid, and intestinal diseases.

Device Description

The Alkaline Phosphatase assay is an automated clinical chemistry assay.

Alkaline phosphatase in the sample catalyzes the hydrolysis of colorless p-nitrophenyl phosphate (p-NPP) to give p-nitrophenol and inorganic phosphate. At the pH of the assay (alkaline), the p-nitrophenol is in the yellow phenoxide form. The rate of absorbance increase at 404 nm is directly proportional to the alkaline phosphatase activity in the sample. Optimized concentrations of zinc and magnesium ions are present to activate the alkaline phosphatase in the sample.

AI/ML Overview

The FDA document provided is a 510(k) premarket notification for an in vitro diagnostic device, the Alkaline Phosphatase assay. This type of submission focuses on demonstrating substantial equivalence to a legally marketed predicate device, rather than proving safety and effectiveness de novo. Therefore, the information provided relates to testing done to establish equivalence for a pre-existing device with modifications, not a new device.

The study proves that the modified device meets acceptance criteria, primarily by demonstrating that it performs equivalently to the predicate device and that incremental changes do not adversely affect its performance.

Here's an analysis of the acceptance criteria and the study that proves the device meets those criteria, based on the provided text.

Acceptance Criteria and Reported Device Performance

The document provides a general statement that the device "met the pre-defined product requirements for all characteristics evaluated in the verification studies." It doesn't present a specific table of acceptance criteria vs. performance in the typical format of a clinical study, but rather a comparison of characteristics to a predicate device and a statement about the results of verification studies.

The key acceptance criterion discussed is substantial equivalence to the predicate device (K023807), particularly regarding:

Intended Use and Indications for Use: The subject device is intended for the same use as the predicate: "quantitation of alkaline phosphatase in human serum or plasma," as an aid in diagnosis and treatment of various diseases.
Methodology and Assay Principle: Both use para-nitrophenyl phosphate and a kinetic measurement method.
Performance (specifically after IFCC calibration factor change): The 6.5% increase in reported results due to the optional IFCC calibration factor is deemed acceptable because it falls within the acceptable assay bias specifications (up to +/-10%) and the customer would be aware of this change.
Risk Mitigation: The comprehensive risk-based assessment for all changes ensured that "the accumulated modifications did not impact the performance of the device."

Since this is an in vitro diagnostic device for measuring a specific analyte (Alkaline Phosphatase), the "performance" here refers to analytical performance characteristics rather than clinical diagnostic accuracy in the way a medical imaging AI would.

Here's a table summarizing the implicit acceptance criteria and the reported performance as derived from the document:

Acceptance Criteria Category	Specific Acceptance Criterion (Implicit)	Reported Device Performance and Conclusion
Intended Use	Match predicate's intended use.	"The Alkaline Phosphatase assay is used for the quantitation of alkaline phosphatase in human serum or plasma." and "Measurements of alkaline phosphatase or its isoenzymes are to be used as an aid in the diagnosis and treatment of liver, bone, parathyroid, and intestinal diseases." - Matches predicate.
Methodology / Assay Principle	Match predicate's core analytical method (para-nitrophenyl phosphate).	"Para-nitrophenyl phosphate" methodology and "Same" assay principle as predicate. - Matches predicate.
Specimen Type	Match predicate's accepted specimen types.	"Human serum or plasma" - Matches predicate. Minor differences in specific tube types cited, but overall specimen type is equivalent.
Performance (Post-Modification)	All "pre-defined product requirements" regarding characteristics evaluated in verification studies must be met. Specifically, for the IFCC calibration factor: results shift must be within acceptable assay bias specifications (up to +/-10%) and not cause incorrect results, with awareness to the user. Overall, modifications should not impact device performance negatively.	"The Alkaline Phosphatase assay, evaluated using the optional calibration factor of 2290 on the ARCHITECT c System, met the pre-defined product requirements for all characteristics evaluated in the verification studies." The 6.5% increase in reported results due to the IFCC calibration factor "is within the acceptable assay bias specifications (up to +/-10%) and thus does not have a potential to cause incorrect results." The comprehensive risk-based assessment concluded that "the accumulated modifications did not impact the performance of the device." - Criteria Met.
Risk Assessment	Comprehensive risk-based assessment conducted for all changes, including risk control measures and verification/validation activities. The aim is to demonstrate that modifications do not impact performance and support substantial equivalence.	"Abbott performed a comprehensive risk-based assessment for each of the changes listed... The assessment includes all risks associated with each device modification, risk control measures to mitigate each identified risk, and the verification and/or validation activities required... The risk control measures show that the accumulated modifications did not impact the performance of the device." - Criteria Met.

Study Details (based on the provided text, which is an FDA clearance letter for an IVD, not a detailed study report for AI/imaging device)

The document relates to modifications made to an existing in vitro diagnostic (IVD) device, not a new AI-powered diagnostic for imaging. Therefore, many of the typical questions for an AI/imaging device (e.g., sample size for test set, expert readers, MRMC study, ground truth for imaging) are not directly applicable or detailed in this type of FDA letter.

However, based on the information provided, we can infer some details relevant to an IVD device:

Sample Size used for the test set and the data provenance:
- Sample Size: Not explicitly stated. The document refers to "verification studies" which typically involve testing samples across the measurement range, parallelism, interference, precision, etc. for an IVD. The exact number of samples (patients or analytical runs) isn't specified in this summary.
- Data Provenance: Not specified regarding country of origin. The studies are described as "verification studies" and "comprehensive risk-based assessment." For IVDs, these are typically prospective laboratory studies conducted by the manufacturer to validate performance characteristics. It's safe to assume they were laboratory-controlled, likely prospective.
Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- This question is not applicable in the context of this IVD device. "Ground truth" for an IVD like Alkaline Phosphatase is established by the analytical measurement itself, often compared to reference methods or known concentrations, or through internal validation against established performance claims. It does not involve human expert interpretation of an image or signal.
Adjudication method (e.g. 2+1, 3+1, none) for the test set:
- This question is not applicable for this IVD. Adjudication methods like 2+1 or 3+1 are used in AI/imaging studies where multiple human readers interpret data that then needs to be reconciled to establish a "ground truth" for comparison with AI. For an IVD, there isn't subjective interpretation of this kind. The measurement process itself generates the result.
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:
- This type of study is not applicable to this IVD. MRMC studies are specific to AI-assisted imaging diagnostics, evaluating the impact of AI on human reader performance. This device provides a quantitative biochemical measurement, not an image for human interpretation.
If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:
- In a sense, yes, the fundamental performance of the IVD is "standalone" in that the automated analyzer (ARCHITECT c System) quantitatively measures alkaline phosphatase activity. The "algorithm" here is the chemical reaction and photometric measurement, and its output is a numerical value (U/L). The verification studies would assess this standalone analytical performance (e.g., precision, accuracy, linearity, detection limits) against pre-defined specifications. The IFCC factor is a mathematical change to this standalone output.
The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
- For an IVD like this, "ground truth" is typically established through:
  - Reference Methods: Comparison of results to established, highly accurate reference methods for alkaline phosphatase.
  - Known Concentrations: Testing samples with precisely known concentrations of alkaline phosphatase.
  - Clinical Correlation: Demonstrating that the assay measures the analyte in patient samples consistently and reliably across relevant patient populations, although the primary ground truth is analytical.
- The document implies that the "pre-defined product requirements" and "acceptable assay bias specifications" served as the benchmarks for determining if the device performed acceptably. The 6.5% shift from the IFCC factor was evaluated against these analytical specifications.
The sample size for the training set:
- This question is not directly applicable in the context of a traditional IVD chemical assay development, as there isn't an "AI model" that requires a training set in the typical sense. The "training" for such a system would be the chemical formulation and instrument calibration based on extensive R&D and optimization, not a data-driven machine learning process. The "validation" of the final product involves the verification studies mentioned.
How the ground truth for the training set was established:
- As above, not directly applicable. The IVD operates on established biochemical principles. Its "ground truth" for development and optimization would be based on fundamental chemistry, enzyme kinetics, and metrological traceability to international standards (e.g., IFCC reference methods for calibrator values).

Summary

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October 16, 2024

Abbott Laboratories Diagnostics Division Bryant Tate Manager of Regulatory Affairs 1915 Hurd Drive, Department RA11, Building LC 8 - 4th Floor MS 8-9 Irving, Texas 75038

Re: K240468

Trade/Device Name: Alkaline Phosphatase Regulation Number: 21 CFR 862.1050 Regulation Name: Alkaline Phosphatase Or Isoenzymes Test System Regulatory Class: Class II Product Code: CJE Dated: September 16, 2024 Received: September 16, 2024

Dear Bryant Tate:

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 (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. Although this letter refers to your product as a device, please be aware that some cleared products may instead be combination products. The 510(k) Premarket Notification Database available at https://www.accessdata.fda.gov/scripts/cdrb/cfdocs/cfpmn/pmn.cfm identifies combination product submissions. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.

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.

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Additional information about changes that may require a new premarket notification are provided in the FDA guidance documents entitled "Deciding When to Submit a 510(k) for a Change to an Existing Device" (https://www.fda.gov/media/99812/download) and "Deciding When to Submit a 510(k) for a Software Change to an Existing Device" (https://www.fda.gov/media/99785/download).

Your device is also subject to, among other requirements, the Quality System (QS) regulation (21 CFR Part 820), which includes, but is not limited to, 21 CFR 820.30. Design controls; 21 CFR 820.90. Nonconforming product; and 21 CFR 820.100, Corrective and preventive action. Please note that regardless of whether a change requires premarket review, the QS regulation requires device manufacturers to review and approve changes to device design and production (21 CFR 820.30 and 21 CFR 820.70) and document changes and approvals in the device master record (21 CFR 820.181).

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 Part 801 and Part 809); medical device reporting of medical device-related adverse events) (21 CFR Part 803) for devices or postmarketing safety reporting (21 CFR Part 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safetyreporting-combination-products); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR Part 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR Parts 1000-1050.

All medical devices, including Class I and unclassified devices and combination product device constituent parts are required to be in compliance with the final Unique Device Identification System rule ("UDI Rule"). The UDI Rule requires, among other things, that a device bear a unique device identifier (UDI) on its label and package (21 CFR 801.20(a)) unless an exception or alternative applies (21 CFR 801.20(b)) and that the dates on the device label be formatted in accordance with 21 CFR 801.18. The UDI Rule (21 CFR 830.300(a) and 830.320(b)) also requires that certain information be submitted to the Global Unique Device Identification Database (GUDID) (21 CFR Part 830 Subpart E). For additional information on these requirements, please see the UDI System webpage at https://www.fda.gov/medical-device-advicecomprehensive-regulatory-assistance/unique-device-identification-system-udi-system.

Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to https://www.fda.gov/medical-device-safety/medical-device-reportingmdr-how-report-medical-device-problems.

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Page

For comprehensive regulatory information about medical devices and radiation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medicaldevices/device-advice-comprehensive-regulatory-assistance) and CDRH Learn (https://www.fda.gov/training-and-continuing-education/cdrh-learn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See the DICE website (https://www.fda.gov/medical-device-advice-comprehensive-regulatoryassistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email (DICE@fda.hhs.gov) or phone (1-800-638-2041 or 301-796-7100).

Sincerely,

Paula V. Caposino -S

Paula Caposino, Ph.D. Deputy Director Division of Chemistry and Toxicology Devices OHT7: Office of In Vitro Diagnostics Office of Product Evaluation and Quality Center for Devices and Radiological Health

Enclosure

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Indications for Use

510(k) Number (if known) K240468

Device Name Alkaline Phosphatase

Indications for Use (Describe)

The Alkaline Phosphatase assay is used for the quantitation of alkaline phosphatase in human serum or plasma.

Measurements of alkaline phosphatase or its isoenzymes are to be used as an aid in the diagnosis and treatment of liver, bone, parathyroid, and intestinal diseases.

Type of Use (Select one or both, as applicable)
☑ Prescription Use (Part 21 CFR 801 Subpart D)	☐ Over-The-Counter Use (21 CFR 801 Subpart C)

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510(k) Summary

This summary of the 510(k) safety and effectiveness information is being submitted in accordance with the requirements of SMDA 1990 and 21 CFR § 807.92.

I. 510(k) Number

K240468

II. Applicant Name

Abbott Laboratories Diagnostics Division 1915 Hurd Drive Department RA11, Building LC 8 - 4th Floor MS 8-9 Irving, TX 75038 United States

Primary contact person for all communications:

Bryant Tate, Manager of Regulatory Affairs Abbott Laboratories, Core Diagnostics bryant.tate(@abbott.com Primary Phone (214) 862-6620 Alternate Phone (972) 518-6260

Secondary contact person for all communications:

Jacek Gorzowski, Director of Regulatory Affairs Abbott Laboratories, Core Diagnostics jacek.gorzowski@abbott.com Phone (224) 668-1740

Date Summary Prepared: October 16, 2024

III. Device Name

Device Trade Name: Alkaline Phosphatase

Common Name: Alkaline phosphatase or isoenzymes test system Classification Name: Nitropheny|phosphate, Alkaline Phosphatase Or Isoenzymes Governing Regulation Number: 21 CFR §862.1050 Product Code: CJE

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IV. Legally Marketed Predicate Device

Predicate Number: K023807 Predicate Trade Name: Alkaline Phosphatase Product Code: CJE

V. Device Description Summary

The Alkaline Phosphatase assay is an automated clinical chemistry assay.

The kit configurations of the Alkaline Phosphatase reagent kits are described below.

	List Number
	7D55-22	7D55-32
Estimated tests per kit	1,500*	11,358*
Reagent 1 (R1)	5 x 21 mL	10 x 84 mL
Reagent 2 (R2)	5 x 9 mL	10 x 26 mL

*Calculation is based on the minimum reagent fill volume per kit.

Reactive Ingredients	Concentration
R12-amino-2-methylpropanolMagnesiumZinc sulfateHEDTA	> 1.2 mol/L
	> 7.2 mmol/L
	> 3.6 mmol/L
	> 7.2 mmol/L
	R24-nitrophenyl phosphate

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VI. Intended Use/Indications for Use

The Alkaline Phosphatase assay is used for the quantitation of alkaline phosphatase in human serum or plasma.

Measurements of alkaline phosphatase or its isoenzymes are to be used as an aid in the diagnosis and treatment of liver, bone, parathyroid, and intestinal diseases.

VII. Technological Comparison

The similarities and differences between the subject device (Alkaline Phosphatase) and the predicate device (Alkaline Phosphatase [K023807]) are presented in the following table.

	Subject Device:Alkaline Phosphatase	Cleared Predicate Device:Alkaline PhosphataseSpecial 510(k) K023807
Characteristics	Alkaline Phosphatase
General Device Characteristic Similarities
Platform	ARCHITECT c8000 instrument	Same
Intended Use andIndications forUse	The Alkaline Phosphatase assay isused for the quantitation of alkalinephosphatase in human serum orplasma.	Same
Methodology	Para-nitrophenyl phosphate	Same
Specimen Type	Human serum or plasma	Same
Assay Principle /Principle ofProcedure	Several substrates have been used tomeasure alkaline phosphatase activitysuch as glycerophosphate,1 phenylphosphate,1 and p-nitrophenylphosphate.2 Bowers and McComb3improved the method of Bessey et al.to include a kinetic measurement.Tietz et al.4 optimized this method to	Same
Characteristics	Subject Device:Alkaline Phosphataseinclude a chelated metal-ion buffer ofzinc, magnesium, and HEDTA. ThisAlkaline Phosphatase procedure is amodification of this method. Alkalinephosphatase in the sample catalyzesthe hydrolysis of colorlessp-nitrophenyl phosphate (p-NPP) togive p-nitrophenol and inorganicphosphate. At the pH of the assay(alkaline), the p-nitrophenol is in theyellow phenoxide form. The rate ofabsorbance increase at 404 nm isdirectly proportional to the alkalinephosphatase activity in the sample.Optimized concentrations of zinc andmagnesium ions are present to activatethe alkaline phosphatase in the sample.	Cleared Predicate Device:Alkaline PhosphataseSpecial 510(k) K023807
Use of Calibrators	No	Same
Use of Controls	Yes	Same
General Device Characteristic Differences
LegalManufacturer	Abbott GmbH & Co. KGMax-Planck-Ring 265205 WiesbadenGermany	Abbott LaboratoriesAbbott Park, IL 60064, USA
R2 ReagentFormulation	Ingredients	Concentration
	4-nitrophenyl phosphate	> 171.6 mmol/L
	Tris hydroxymethyl aminomethaneSodium Chloride4-Hydroxybenzoic acidProclin 300Proclin 950	1.12%0.001%5.6%0.5 g/L1 g/L
Reagent KitComponents	Reagent Kit (List Number 7D55-32)Reagent 1 (R1) 10 x 84 mLReagent 2 (R2) 10 x 26 mLEstimated tests per kit: 11,358Reagent Kit (List Number 7D55-22)	Reagent Kit (List Number 7D55-20)Reagent 1 (R1) 10 x 84 mLReagent 2 (R2) 10 x 35 mLEstimated tests per kit:11,358Reagent Kit (List Number 7D55-30)
Characteristics	Subject Device:Alkaline Phosphatase	Cleared Predicate Device:Alkaline PhosphataseSpecial 510(k) K023807
	Reagent 1 (R1) 5 x 21 mL	Reagent 1 (R1) 5 x 48 mL
	Reagent 2 (R2) 5 x 9 mL	Reagent 2 (R2) 5 x 22 mL
	Estimated tests per kit: 1,500	Estimated tests per kit: 3,165
Assay Parameters,Assay VolumeRequirements	R1 60R2 20Water volume: 125 45	R1 60R2 20Water volume: 170 0
Lower Limits ofMeasurement	Limit of Detection: 5.0 U/LLimit of Quantitation: 5.0 U/L	Limit of Detection: 1.9 U/LLimit of Quantitation: 5.0 U/L
On-BoardStability	8 Days	13 Days
Tube Types	Serum:- Serum tubes- Serum separator tubesPlasma:- Lithium heparin tubes- Lithium heparin separator tubes- Sodium heparin tubes	Serum:- Serum tubes- Serum separator tubesPlasma:- Lithium heparin tubes- Ammonium heparin- Sodium heparin tubes
Linearity	Linear up to 2,200 U/L (2343 U/L using IFCC factor)Flex Rate Linearity is 4555 U/L (4851 U/L using IFCC factor)	Linear up to 2200 U/LFlex Rate Linearity up to4555 U/L
Standardization	Molar extinction of p -nitrophenol (non-IFCC method)IFCC* reference method	Molar extinction of p -nitrophenol (non-IFCC method)
CalibrationMethod	Factor Method (calibration factor of 2150, original, or 2290, traceable to IECC)	Factor Method (calibration factor of 2150)

1 King EJ, Armstrong AR. A convenient method for determining serum and bile phosphatase activity. Can Med Assoc J 1934;31:376-381.

2 Bessey OA, Lowry OH, Brock MJ. A method for the rapid determination of alkaline phosphatase with five cubic millimeters of serum. J Biol Chem 1946;164:321-329.

3 Bowers GN, McComb RB. A continuous spectrophotometric method for measuring the activity of serum alkaline phosphatase. Clin Chem 1966:12(2):70-89.

4 Tietz NW, Burtis CA, Duncan P, et al. A reference method for measurement of alkaline phosphatase activity in human serum. Clin Chem 1983;29(5):751-761.

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IFCC = International Federation of Clinical Chemistry and Laboratory Medicine

VIII. Non-Clinical and/or Clinical Tests Summary & Conclusions

The Alkaline Phosphatase assay, evaluated using the optional calibration factor of 2290 on the ARCHITECT c System, met the pre-defined product requirements for all characteristics evaluated in the verification studies

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The IFCC calibration factor (2290) represents only a mathematical factor change from the non-IFCC factor. Use of the IFCC calibration factor results in a 6.5% increase in reported results throughout the measurement range of the assay when compared to the unmodified predicate device. A shift of 6.5% is within the acceptable assay bias specifications (up to +/-10%) and thus does not have a potential to cause incorrect results. Furthermore, since the IFCC calibration factor is optional, it requires the customer to manually change the calibration factor parameter in the instrument, so the customer would be aware when they switched to using the IFCC calibration factor and would therefore be aware of the potential shift in results.

In addition to the implementation of the optional IFCC-based calibration factor, several other changes were made to the device since its clearance in 2002. Abbott performed a comprehensive risk-based assessment for each of the changes listed in the Alkaline Phosphatase Special 510(k) (K240468). The assessment includes all risks associated with each device modification, risk control measures to mitigate each identified risk, and the verification and/or validation activities required (including a summary of test methods, acceptance criteria, results, and why each is adequate to support substantial equivalence). The risk control measures show that the accumulated modifications did not impact the performance of the device. In conclusion, the modified device is therefore deemed to be substantially equivalent to the predicate device (cleared under K023807) as demonstrated by results obtained in the studies.

Regulation Number and Section

§ 862.1050 Alkaline phosphatase or isoenzymes test system.

(a)
Identification. An alkaline phosphatase or isoenzymes test system is a device intended to measure alkaline phosphatase or its isoenzymes (a group of enzymes with similar biological activity) in serum or plasma. Measurements of alkaline phosphatase or its isoenzymes are used in the diagnosis and treatment of liver, bone, parathyroid, and intestinal diseases.(b)
Classification. Class II.