Lab-developed test
Also called Laboratory-developed test, LDT
A lab-developed test (LDT), also called a laboratory-developed test, is a diagnostic test that is designed, manufactured and used within a single clinical laboratory, rather than a commercial test kit sold to many laboratories. Like other lab tests, it examines a sample such as blood, saliva or stool to measure or detect markers in the body.
The laboratory running it must be certified under CLIA (the Clinical Laboratory Improvement Amendments), the program run by the Centers for Medicare & Medicaid Services that sets quality standards for how testing is performed. CLIA covers whether a test measures accurately; it does not establish whether the result is clinically useful. An LDT has not been cleared or approved by the FDA. The FDA issued a rule in 2024 to regulate LDTs as medical devices, a federal court vacated it in 2025, and the FDA has since restored its earlier regulation.
Why it matters after 45
Some of the newer tests marketed for midlife health, including multi-cancer early detection, detailed hormone-metabolite panels and gut microbiome panels, are LDTs. They can add information, but they are interpreted alongside a clinical history and standard testing, and they are intended to add to, not replace, recommended screening.
Where it comes up
Related terms
References
- U.S. Food and Drug Administration. FDA Proposes Rule Aimed at Helping to Ensure Safety and Effectiveness of Laboratory Developed Tests. 2023. https://www.fda.gov/news-events/press-announcements/fda-proposes-rule-aimed-helping-ensure-safety-and-effectiveness-laboratory-developed-tests
- U.S. Food and Drug Administration. Laboratory Developed Tests. https://www.fda.gov/medical-devices/in-vitro-diagnostics/laboratory-developed-tests
- Centers for Medicare & Medicaid Services. Clinical Laboratory Improvement Amendments (CLIA). https://www.cms.gov/medicare/quality/clinical-laboratory-improvement-amendments
- MedlinePlus. How can I be sure a genetic test is valid and useful? U.S. National Library of Medicine. https://medlineplus.gov/genetics/understanding/testing/validtest/
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