LDTs are diagnostic tests developed and performed by a single high-complexity CLIA-certified laboratory rather than distributed as kits. FDA historically exercised enforcement discretion; a 2024 final rule began phasing in active oversight. FDA issued a rule in 2024 to phase in oversight of LDTs, but a federal court vacated it in March 2025, so LDTs remain primarily under CLIA. Laboratories must still validate performance and meet CLIA quality rules. In the EU, health institution exemptions under IVDR Article 5(5) play a similar role with strict conditions.

Why it matters

Many oncology, infectious disease, and rare-disease tests reached patients as LDTs. The FDA LDT rule, ongoing litigation, and CMS PAMA repricing are key uncertainties.

Common pitfalls

•A key misconception is that CLIA certification alone is sufficient for regulatory compliance of an LDT.
•Some assume that all LDTs are exempt from FDA regulation, which is no longer the case with the implementation of new oversight.
•Neglecting to consider the phased implementation schedule of the FDA’s new LDT rule can lead to significant compliance gaps.

Sources

FDA LDT final rule · FDA
AdvaMed - Industry Reports · AdvaMed
MedTech Europe - Facts & Figures · MedTech Europe

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Regulatory pathway choice - 510(k) vs PMA, 510(k) vs De Novo, Abbreviated vs Special 510(k).
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