K982251 · Sigma Diagnostics, Inc. · CDO · Aug 18, 1998 · Clinical Chemistry
Device Facts
Record ID
K982251
Device Name
SIGMA DIAGNOSTICS INFINITY URIC ACID REAGENT KIT
Applicant
Sigma Diagnostics, Inc.
Product Code
CDO · Clinical Chemistry
Decision Date
Aug 18, 1998
Decision
SESE
Submission Type
Traditional
Regulation
21 CFR 862.1775
Device Class
Class 1
Indications for Use
The Sigma Diagnostics INFINITY™ Uric Acid Reagent is a device intended to measure uric acid in serum. Measurements obtained by the device are used in the diagnosis and treatment of numerous renal and metabolic disorders, including renal failure, gout, leukemia, psoriasis, starvation or other wasting conditions, and of patients receiving cytotoxic drugs.
Device Story
INFINITY™ Uric Acid Reagent is an in vitro diagnostic chemical assay for measuring uric acid levels in human serum or urine. The device utilizes a modified Trinder peroxide assay based on the methods of Trivedi and Kabasakallan. The biochemical process involves two steps: 1) Uricase oxidizes uric acid to allantoin, producing hydrogen peroxide (H2O2); 2) Peroxidase catalyzes a reaction between H2O2, 4-aminoantipyrine (4-AAP), and 2,4,6-Tribromo-3-hydroxy benzoic acid (TBHB) to form a quinoneimine dye. The resulting change in absorbance at 520 nm is measured via automated or manual spectrophotometric systems. The intensity of the color change is directly proportional to the uric acid concentration in the sample. Clinicians use these quantitative results to assess purine metabolism and diagnose conditions like gout, renal dysfunction, and metabolic disorders. The reagent is intended for professional laboratory use.
Clinical Evidence
Bench testing only. The device relies on established biochemical assay principles (modified Trinder peroxide assay) and equivalence to a previously cleared predicate device.
Technological Characteristics
In vitro diagnostic reagent kit. Chemistry: Uricase/peroxidase enzymatic assay using 2,4,6-Tribromo-3-hydroxy benzoic acid (TBHB) as a chromogen. Detection: Spectrophotometric absorbance at 520 nm (range 500-550 nm). Compatible with automated and manual clinical chemistry analyzers.
Indications for Use
Indicated for the quantitative determination of uric acid in human serum or urine to aid in the diagnosis and treatment of renal and metabolic disorders such as renal failure, gout, leukemia, psoriasis, starvation, wasting conditions, and monitoring patients on cytotoxic drugs.
Regulatory Classification
Identification
A uric acid test system is a device intended to measure uric acid in serum, plasma, and urine. Measurements obtained by this device are used in the diagnosis and treatment of numerous renal and metabolic disorders, including renal failure, gout, leukemia, psoriasis, starvation or other wasting conditions, and of patients receiving cytotoxic drugs.
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## 510(k) SUMMARY OF SAFETY AND EFFECTIVENESS
INFINITY™ Uric Acid Reagent, Procedure 684
Sigma Diagnostics INFINITY™ Uric Acid Reagent is intended for the in vitro quantitative, diagnostic determination of uric acid in human serum or urine on both automated and manual systems.
Uric acid is a metabolite of purines, nucleic acids and nucleoproteins. Consequently, abnormal levels may be indicative of a disorder in the metabolism of these substances. Hyperuricaemia may be observed in renal dysfunction, gout, leukemia, polycythaemia, atherosclerosis, diabetes, hypothyroidism, or in some genetic diseases. Decreased levels are present in patients with Wilson's Disease.1-3
This reagent is based upon the methods of Trivedi and Kabasakallan45 with a modified Trinder8 peroxide assay using 2,4,6-Tribromo-3-hydroxy benzoic acid (TBHB).
The series of reactions involved in the assay system is as follows:
- Uric Acid is oxidized to allantoin by uricase with the production of H2O2. 1.
Uric Acid + O2 + H2O Uricase > Allantoin + CO2 + H2O2
- The peroxide reacts with 4-aminoantipyrine (4-AAP) and TBHB in the presence of 2. peroxidase to yield a quinoneimine dye. The resulting change in absorbance at 520 nm (500-550 nm) is proportional to uric acid concentration in the sample.
H2O2 + 4-AAP + TBHB Peroxidase > Quinoneimine + H2O
The Sigma Diagnostics INFINITY™ Uric Acid Reagent (Procedure No. 684) is substantially equivalent to, and is the same product as the TRACE Scientific Uric Acid Reagent kit cleared by the FDA as K971485.
## References
- Searcy RL: Diagnostic Biochemistry. McGraw-Hill, New York, NY, 1969 】.
- Henry RJ, Common C, Winkelman JW (eds), Clinical Chemistry: Principles and 2. Techniques. Harper & Row, Hagerstown, MD, 1974
- 3. Balls ME: Adv Clin Chem 18:213, 1976
- Trivedi R, Berta E, Rebar L: Clin Chem, 22:1223, 1976 4.
- Kabasakallan P, Kalliney S, Wescott A: Clin Chem, 19:522, 1973 న.
- Trinder P: J Clin Pathol, 22:246, 1949 6.
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Image /page/1/Picture/1 description: The image shows the logo for the U.S. Department of Health & Human Services. The logo features a stylized eagle with three stripes representing the department's mission. The text "DEPARTMENT OF HEALTH & HUMAN SERVICES • USA" is arranged in a circular pattern around the eagle. The logo is black and white.
Food and Druq Administration 2098 Gaither Road Rockville MD 20850
AUG 1 8 1998
William Gilbert, Ph.D. Manager, Scientific Affairs Sigma Diagnostics Inc. 545 South Ewing Avenue St. Louis, Missouri 63103
Re : K982251 INFINITY™ Uric Acid Reagent (Procedure No. 684) Requlatory Class: I Product Code: CDO Dated: June 23, 1998 Received: June 26, 1998
Dear Dr. Gilbert:
We have reviewed your Section 510(k) notification of intent to market the device referenced above and we have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to 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). You may, therefore, market the device, subject to the general controls provisions The general controls provisions of the Act of the Act. include requirements for annual registration, listing 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 (Premarket Approval), it may be subject to such additional controls. Existing major regulations affecting your device can be found in the Code of Federal Requlations, Title 21, Parts 800 to 895. ਕੇ substantially equivalent determination assumes compliance with the Current Good Manufacturing Practice requirements, as set forth in the Quality System Requlation (QS) for Medical Devices: General regulation (21 CFR Part 820) and that, through periodic QS inspections, the Food and Drug Administration (FDA) will verify such assumptions. Failure to comply with the GMP regulation may result in regulatory In addition, FDA may publish further announcements action. concerning your device in the Federal Register. Please note: this response to your premarket notification submission does not affect any obligation you might have under sections 531 through 542 of the Act for devices under the Electronic Product Radiation Control provisions, or other Federal laws or requlations.
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Under the Clinical Laboratory Improvement Amendments of 1988 (CLIA-88), this device may require a CLIA complexity categorization. To determine if it does, you should contact the Centers for Disease Control and Prevention (CDC) at (770) 488-7655.
This letter will allow you to begin marketing your device as described in your 510 (k) premarket notification. The FDA finding of substantial equivalence of your device to a legally marketed predicate device results in a classification for your device and thus, permits your device to proceed to the market.
If you desire specific advice for your device on our labeling regulation (21 CFR Part 801 and additionally 809.10 for in vitro diagnostic devices), please contact the Office of Compliance at (301) 594-4588. Additionally, for questions on the promotion and advertising of your device, please contact the Office of Compliance at (301) 594-4639. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). Other general information on your responsibilities under the Act may be obtained from the Division of Small Manufacturers Assistance at its toll-free number (800) 638-2041 or (301) 443-6597 or at its internet address "http://www.fda.gov/cdrh/dsmamain.html".
Sincerely yours,
Steven Litman
Steven I. Gutman, M.D., M.B.A. Director Division of Clinical Laboratory Devices Office of Device Evaluation Center for Devices and Radiological Health
Enclosure
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510(k) Number (if known):
Device Name: INFINITY ™ Uric Acid Reagent ___
## Indications For Use:
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The Sigma Diagnostics INFINITY™ Uric Acid Reagent is a device intended to measure uric acid in serum. Measurements obtained by the device are used in the diagnosis and treatment of numerous renal and metabolic disorders, including renal failure, gout, leukemia, psoriasis, starvation or other wasting conditions, and of patients receiving cytotoxic drugs.
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Concurrence of CDRH, Office of Device Evaluation (ODE)
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| Over-The-Counter Use | |
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(Division Sign-Off)
Division of Clinical Laboratory Devices
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Two short videos show you everything — or skip straight to the written tutorial if you'd rather read. You can reopen this any time from the Tutorial button in the top bar.
Part 1 — Search, results, and everyday workflows 16 min
Part 2 — Embeddings: the galaxy map 3 min
1. Search: exact and fuzzy
Type a phrase like "coronary artery calcification" into the search box. You get two kinds of results. Exact results match the literal phrase — prefix searches work ("coronary artery calcificati") but suffix searches do not. Fuzzy results match on the meaning and intent of your phrase rather than the exact words, and are sorted by relevance score. Hover over the Exact or Fuzzy badge on any row to see exactly why it matched.
Use the checkboxes above the results to narrow: SaMD keeps only software-only devices, AI / ML keeps only devices with AI.
Exact vs. fuzzy search: what's the difference?
Exact matches on the literal phrase (prefix search works, suffix does not). Fuzzy matches on the meaning and intent of the phrase rather than the exact words. Hover over the badge on any row to see why it matched.
You search "coronary artery calcification" and want only software devices with AI. What two filters do you apply?
Narrow by SaMD (software-only devices), then narrow by AI/ML (devices with AI).
2. The results table
Scroll right in the results table. The intended use is extracted for you — no need to open the PDF. The device story gives a high-level snapshot of what the device does and how it's used. The AI Performance sub-table shows each output name, acceptance criteria, observed values, and development/test dataset descriptions — the same format Innolitics uses for regulatory strategy outputs, and the fastest high-level fingerprint of an AI device. It is AI-generated but has been very reliable in practice.
Where do you find a device's intended use without opening the PDF?
Scroll right in the search results table. The intended use column is extracted for you; no need to dig into the 510(k) summary PDF.
What does the AI Performance sub-table show, and why is it useful?
Output name, acceptance criteria, observed values, development dataset description, and test dataset description. It's the same format we use for regulatory strategy output and Fast 510(k) input, and the fastest high-level fingerprint of an AI device. AI-generated but reliable in practice.
3. Judging fuzzy relevance
Fuzzy results trail off in relevance as you scroll. Use three signals to decide how far down to go: the fuzzy badge explanations, the intended use column, and whether your target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, you're past the relevant zone. A top hit with a low score (~0.4) and a stretched explanation is a hint the closest predicates are far away — the project may be headed for De Novo. Note the fuzzy search is a pattern match: it doesn't handle negation ("not") well, and hardware devices can appear — filter by SaMD/AI ML to cut them.
How do you judge how far down fuzzy search results to go?
Use the relevancy signals: the fuzzy badge explanations, the intended use column, and whether the target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, results are trailing off in relevancy.
4. Device detail page: chat and citations
Click a device name to open its detail page: device facts on the left, a chat window on the right. Ask something like "Describe the training data". The answer carries little citation bubbles — click one to jump to the highlighted passage in the source PDF, so you can verify every AI answer against the document. There's also a Download PDF button for sharing.
How do you verify an AI chat answer on the device detail page?
Click the citation bubbles to jump to the relevant highlight in the source document.
Reading rule for every project: how many summaries do you read in full?
At least the three most relevant 510(k) or De Novo summaries, in full. After that, use targeted chat questions to confirm your memory quickly. The tool supports this professional habit — it doesn't replace it.
5. Side-by-side comparison
Select multiple rows in the results table (aim for under ~10), then open the PDF Viewer tab. Ask one question — it goes to all selected devices in parallel, each with citations. This is the fastest way to compare and contrast devices: training data, PCCP scope, how they handled adding new scanners, and so on.
What does the side-by-side PDF viewer mode do?
Select multiple devices, open the PDF viewer tab, and ask one question (e.g., "Describe the training data"). It queries all selected devices simultaneously with citations, so you can compare and contrast quickly.
6. Collections
With rows selected, go to the Collections tab and create a labeled collection (e.g., "Cobb Angle Project"). Reload that selection any time — before a client call, pull up the collection and ask questions across all of its devices at once.
How do you save a set of selected devices for later use?
Select the rows, go to the Collections tab, and create a labeled collection (e.g., "Cobb Angle Project"). You can reload the selection anytime and carry it into the PDF viewer and other tabs that support selections.
7. Product codes and the regulations tree
Click a product code in the results to jump to it in the regulations tree — identification text, sibling product codes, and devices you can open in a PDF viewer on the right. Click a regulation number to see its identification, special controls, and related product codes. You can also search by product code or regulation number at the top of the tree. Always read the special controls if any exist for your device — it broadens your search and sharpens pre-kickoff research.
What can you do from the regulations tree view?
Browse product codes and regulation numbers, read the identification text and special controls, browse sibling product codes, open device PDFs on the right, and search by product code or regulation number at the top of the tree.
8. Chart view
Click Show Chart and segment by regulation number (or product code) to see which regulations dominate your result set. Clicking a regulation takes you into the regulations tree. Great for spotting that most matches are, say, hardware laparoscopic devices — a cue to go back and filter.
How do you see which regulations dominate a search result set?
Click "Show Chart" and segment by Regulation Number. Clicking a regulation takes you to the regulations tree.
9. The predicate graph
Open the Predicates tab for a family-tree view of predicate relationships. Click a node to trace its parents and children; selections from search carry over pre-selected. Commonly predicated devices are worth reading — a lot of people predicated them for a reason. The visual lineage is also handy on client calls, e.g. to show how a predicate family evolved and justify why your predicate still holds.
In the predicate graph, why are commonly predicated devices worth reading?
A lot of people predicated them for a reason. Clicking a node traces parents and children, and selections from search carry over pre-selected.
10. Embeddings: the galaxy map
The Embeddings tab plots every matching document in a 2-D "galaxy map" where semantically similar devices cluster together. Hover or click clusters to explore, and let AI label the clusters for you. Embeddings beat product codes for grouping: two devices can carry different product codes (LLZ vs. QIH) yet do the same thing — the embedding captures the meaning of the intended use and device story. This is also exactly how retrieval-augmented generation (RAG) works under the hood, and it makes a great visual on client calls.
Try it yourself
Head to the search page and work through a few of these AI/ML fuzzy searches to build intuition: perivascular fat on CT · aortic valve calcification opportunistic screening on noncontrast CT · breast cancer prediction on digital pathology slides · autism detection · gestational age prediction · a hearing aid that can also detect a pulse · foundation model based analysis of ECG · large language models · penetration test. Watch how the relevance scores, intended use, and AI Performance tables tell you when results stop being meaningful.
