Usage Examples
- The assay is an IVD, so the intended use statement on the package insert drives the whole classification argument.
- We shipped it labeled For Research Use Only, which means it carries no IVD claim and cannot support a clinical decision.
- Their IVD went through De Novo because no predicate existed for that biomarker.
What is IVD (In Vitro Diagnostic)?
IVDs are reagents, instruments, and systems intended for use in diagnosing disease or other conditions, including determining a state of health. They are regulated as medical devices but act on specimens taken from the body, not the patient.
IVDs exist as a distinct regulatory category because the test never touches the patient, yet the result decides what happens to them. A wrong answer from an IVD fails silently: nothing breaks, no alarm sounds, a number is simply wrong and a clinician acts on it. FDA therefore regulates the reagent, the instrument, and the claim as one object, and treats the label as the controlled surface.
IVDs cover reagents, instruments, and systems intended for use in diagnosing disease or other conditions, including determining a state of health, per 21 CFR 809.3(a). That scope is wider than the assay chemistry, since the instrument and the system built around it sit inside the definition. Outside the boundary are products making no diagnostic claim, which 21 CFR 809.10(c) confines to Research Use Only or Investigational Use Only labeling.
IVDs are applied in practice through two decisions made early and rarely revisited. The first is the intended use statement, which fixes the claim and therefore the classification. The second is the premarket route that follows from it, the same 510(k), De Novo, and PMA pathways used for other devices. Teams that draft the package insert last end up rebuilding the evidence package around it.
Not to be confused with
- Medical device (in vivo)
- an IVD acts on a specimen already removed from the body, while a conventional device acts on the patient. The consequence is that IVD risk flows through the accuracy of a result, not through direct physical harm.
- Laboratory Developed Test (LDT)
- an IVD designed, manufactured, and used inside one laboratory. The distinction is the manufacturer and site, not the technology. FDA's May 2024 rule writing laboratory manufacturers into the 809.3(a) definition was vacated by a federal court on 31 March 2025, and FDA restored the prior regulatory text in September 2025.
- Companion diagnostic (CDx)
- a subset of IVDs whose result is required for the safe use of a specific therapeutic. Every CDx is an IVD; almost no IVD is a CDx, and the CDx label is tied to the drug's.
- Research Use Only product
- not an IVD in the regulatory sense, because it carries no diagnostic claim. The RUO statement in 21 CFR 809.10(c) is what keeps it outside the category, and promoting it clinically pulls it back in.
Part 809 sits on top of the general device obligations. These are the IVD-specific anchors.
What you must do
- 1Determine whether the product meets the definition before selecting a pathway, since reagents, instruments, and systems intended for diagnostic use are all captured21 CFR 809.3(a)
- 2Place the required information on the product label itself, not only in accompanying material, unless a product-class standard specifies otherwise21 CFR 809.10(a)
- 3State the package insert information in one place, in the format and order the regulation prescribes, rather than scattered across documents21 CFR 809.10(b)
- 4Label a product still in the laboratory research phase "For Research Use Only. Not for use in diagnostic procedures." and make no diagnostic claim for it21 CFR 809.10(c)
- 5Label a product undergoing investigational testing "For Investigational Use Only. The performance characteristics of this product have not been established."21 CFR 809.10(c)
Common mistakes
Selling an RUO-labeled product into clinical use
the RUO statement is a scope boundary, not a disclaimer. Marketing material, sales conversations, or a validation package aimed at clinical decisions establishes a diagnostic intended use, and the product becomes an unapproved IVD regardless of what the label says.
Writing the intended use statement after the studies are done
the claim determines the classification, which determines the evidence required. Teams that generate data first and phrase the claim later routinely find their analytical and clinical validation does not support the claim they need, and repeat the studies.
Assuming the 2024 LDT rule still governs
the May 2024 final rule and its four-year phaseout were vacated on 31 March 2025 and the regulatory text reverted in September 2025. Compliance plans and vendor contracts built against that phaseout timeline are budgeting for obligations that no longer exist.
When This Matters
- The assay is an IVD, so the intended use statement on the package insert drives the whole classification argument.
- We shipped it labeled For Research Use Only, which means it carries no IVD claim and cannot support a clinical decision.
- Their IVD went through De Novo because no predicate existed for that biomarker.
Frequently Asked Questions
Yes. IVDs are regulated as medical devices in the United States, so classification, premarket pathway, quality system, and postmarket reporting obligations all apply. 21 CFR Part 809 layers IVD-specific labeling requirements on top of the general device framework rather than replacing any part of it.
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