FDA Rule Bringing Laboratory-Developed Tests Under Device Law (2024)

Table of Contents

1. What the FDA Did
2. What a Laboratory-Developed Test Is
3. The Reasons the FDA Gave
4. The Planned Four-Year Phaseout in Five Stages
5. Tests the FDA Said It Would Largely Leave Alone
6. Public Comments, Costs and Benefits
7. What the Rule Did Not Do
8. The 2025 Court Decision and the FDA’s Reversal
9. Dates and Status as of 11 October 2026
10. How the Rule Fits Earlier Actions
11. What Published Research Reports on Laboratory-Developed Tests
12. Primary Documents
13. Key Research Papers
14. Connections

1. What the FDA Did

The FDA news release “FDA Takes Action Aimed at Helping to Ensure the Safety and Effectiveness of Laboratory Developed Tests” is dated 29 April 2024. The final rule itself, “Medical Devices; Laboratory Developed Tests,” appeared in the Federal Register on 6 May 2024 at 89 FR 37286 (FR Doc. 2024-08935, RIN 0910-AI85), with an effective date of 5 July 2024. A Federal Register docket is the public file that holds a rulemaking’s documents and the comments people send in; this one is FDA-2023-N-2177.

The rule had two parts:

• A one-line change to the regulations. The FDA’s definition of “in vitro diagnostic products” at 21 CFR 809.3(a) gained the words “including when the manufacturer of these products is a laboratory.” The rule states that this “reflects that the device definition in the FD&C Act does not differentiate between entities manufacturing the device.” It also updated the statutory citation in that section to section 201(h)(1) of the Federal Food, Drug, and Cosmetic Act (FD&C Act).
• A phaseout policy. Alongside the amendment, the FDA announced it was “phasing out its general enforcement discretion approach for LDTs so that IVDs manufactured by a laboratory will generally fall under the same enforcement approach as other IVDs,” over four years, with targeted exceptions for certain categories of tests.

The release quotes FDA Commissioner Robert M. Califf, M.D.: “LDTs are being used more widely than ever before – for use in newborn screening, to help predict a person’s risk of cancer, or aid in diagnosing heart disease and Alzheimer’s. The agency cannot stand by while Americans continue to rely on results of these tests without assurance that they work.”

On 25 June 2024 the FDA announced a companion document, “Laboratory Developed Tests: Small Entity Compliance Guide” (89 FR 53109, same docket), intended to help small laboratories comply with the device requirements as the phaseout proceeded. The notice describes it as guidance that “does not establish any rights for any person and is not binding on FDA or the public.”

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2. What a Laboratory-Developed Test Is

An in vitro diagnostic product (IVD) is, in the FDA’s regulatory definition as the rule summarizes it, a reagent, instrument or system used to examine specimens taken from the body — such as blood, saliva or tissue — to diagnose disease or other conditions or to determine a person’s state of health. The press release gives examples of what such tests measure: proteins, glucose, cholesterol or DNA.

Some IVDs are made by conventional device manufacturers and sold as kits to laboratories, clinicians or, in some cases, patients. Others are made by laboratories. The rule states that the FDA “has generally considered an LDT to be an IVD that is intended for clinical use and that is designed, manufactured, and used within a single laboratory” that is certified under the Clinical Laboratory Improvement Amendments of 1988 (CLIA) to perform high-complexity testing. CLIA is a separate federal program for laboratory quality; the rule states that the Centers for Medicare & Medicaid Services (CMS) administers CLIA, while the FDA administers the FD&C Act.

Enforcement discretion means the agency treats a requirement as applying but generally chooses not to enforce it. The rule states that since implementing the Medical Device Amendments of 1976, the FDA “generally has not enforced applicable legal requirements with respect to most LDTs” — including registration and listing, adverse-event reporting, current good manufacturing practices, and premarket review before a test is used in patient care.

For the purposes of the phaseout, the rule used the phrase “IVDs offered as LDTs” to cover tests made and offered as LDTs by CLIA-certified high-complexity laboratories and used within such laboratories, “even if those IVDs do not fall within FDA’s traditional understanding of an LDT because they are not designed, manufactured, and used within a single laboratory.”

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3. The Reasons the FDA Gave

The tests had changed. The rule states that when the 1976 law took effect, LDTs were “mostly manufactured in small volumes by laboratories that served their local communities,” often for rare diseases, using manual techniques and components legally marketed for clinical use. It states that today many LDTs rely on “high-tech or complex instrumentation and software,” are run in high volume for patients nationwide, and are “more often used to inform or direct critical treatment decisions, to widely screen for common diseases, to predict personal risk of developing certain diseases, and to diagnose serious medical conditions such as cancer and heart disease.”

Evidence of inaccurate tests. The press release states that the FDA “is aware of numerous examples of potentially inaccurate, unsafe, ineffective or poor quality IVDs offered as LDTs that caused or may have caused patient harm, including tests used to select cancer treatment, aid in the diagnosis of COVID-19, aid in the management of patients with rare diseases and identify a patient’s risk of cancer.” It lists the sources of that evidence as published studies, the FDA’s own review experience, news articles and class-action lawsuits.

What could go wrong for patients. The release states that without greater oversight, patients “may be more likely to initiate unnecessary treatment, or delay or forego proper treatment based on inaccurate test results or tests promoted with false or misleading claims.”

Adverse-event reporting catches problems across laboratories. The rule contrasts CLIA, under which complaints are “investigated and monitored generally only on a laboratory-by-laboratory basis,” with FDA device reporting, which is pooled across many sites. As an example it describes how reports from multiple manufacturers showed that high-dose biotin supplements were interfering with certain immunoassays (biotin is commonly built into the design of these assays), causing inaccurate results; the rule states the investigation “led to the redesign of multiple tests on the market.”

Cybersecurity. The rule notes that many LDTs are connected to laboratory information systems that may hold patient genetic information, and that “it has been demonstrated that hackers can modify medical test results.”

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4. The Planned Four-Year Phaseout in Five Stages

The rule stated that “following a 4-year phaseout period, FDA will no longer have a general enforcement discretion approach for LDTs.” Each stage was timed from the rule’s publication date (6 May 2024):

1. Stage 1 — one year after publication: medical device reporting (adverse events), reports of corrections and removals, and complaint-file requirements.
2. Stage 2 — two years after publication: the remaining requirements not covered by other stages, including registration and listing, labeling, and investigational-use requirements.
3. Stage 3 — three years after publication: quality system requirements (the device manufacturing-quality rules in 21 CFR part 820).
4. Stage 4 — three and a half years after publication: premarket review for high-risk tests (those that may be classified into class III, or are subject to licensure under section 351 of the Public Health Service Act).
5. Stage 5 — four years after publication: premarket review for moderate-risk and low-risk tests that require premarket submissions.

For stages 4 and 5, the rule stated that if a premarket submission had been received by the start of the stage, the FDA intended to continue enforcement discretion while it reviewed the submission. Premarket review is the FDA’s evaluation of a device before it is marketed — for medical devices, the rule describes class I (general controls), class II (special controls) and class III (premarket approval) as the three risk classes.

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5. Tests the FDA Said It Would Largely Leave Alone

The rule kept or added targeted enforcement-discretion policies for several categories. The FDA stated it generally did not intend to enforce:

• Premarket review and most quality-system requirements for currently marketed tests first marketed before the rule was issued and not modified (or modified only in limited ways). The press release states this policy “is intended to address the risk that the perceived costs of compliance with such requirements could lead to the widespread loss of access to beneficial IVDs on which patients currently rely.”
• Premarket review and most quality-system requirements for tests made by a laboratory within a health system to meet an unmet need of patients receiving care in that same health system, when an FDA-authorized test is not available.
• Premarket review for tests approved by New York State’s Clinical Laboratory Evaluation Program (NYS CLEP). The rule states that this state program evaluates high- and moderate-risk LDTs for analytical and clinical validity, which “helps to mitigate the risk of harm from inaccurate and unreliable LDTs.”
• All requirements for tests made and performed within the Veterans Health Administration or the Department of Defense.
• Premarket review and most quality-system requirements for certain non-molecular antisera tests for rare red blood cell antigens, made in blood establishments where no alternative exists for a compatible transfusion.
• All requirements, as proposed in 2023, for “1976-Type LDTs,” certain human leukocyte antigen (HLA) tests used in organ, stem cell and tissue transplantation, and tests used solely for forensic (law enforcement) purposes. In the rule’s description, a 1976-Type LDT uses manual techniques performed by specialized laboratory staff and components legally marketed for clinical use, with design, manufacture and use all within a single CLIA-certified high-complexity laboratory.

The press release also announced two draft guidances on the same day, both about tests used during emergencies such as infectious-disease outbreaks.

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6. Public Comments, Costs and Benefits

Comments. The proposed rule was published on 3 October 2023 (88 FR 68006), and its comment period closed on 4 December 2023. The final rule states the FDA received “more than 6,500 comments” from groups including device associations, industry, professional associations, hospitals and academic medical centers, accreditation bodies, advocacy organizations, government agencies and individuals. Supporters pointed to problems with LDTs and the value of a “level playing field” between laboratory and non-laboratory test makers. Other comments raised concerns about the evidence, the sufficiency of CMS oversight, the FDA’s legal authority, effects on access, pricing and innovation, small laboratories and specific patient populations. The FDA stated it made no changes to the regulatory amendment but changed the phaseout policy in response, adding several of the exceptions listed in section 5.

Estimated costs and benefits. The rule estimated annualized benefits over 20 years of $0.99 billion to $11.1 billion at a 7 percent discount rate (primary estimate $3.51 billion), mainly from averted health losses due to problematic tests, and annualized costs of $566 million to $3.56 billion (primary estimate $1.29 billion), mainly laboratories’ compliance costs. At a 3 percent discount rate the primary estimates were $4.34 billion in benefits and $1.37 billion in costs.

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7. What the Rule Did Not Do

• It never reached premarket review. The court vacated the rule on 31 March 2025, before the first stage (one year after publication) began; stages 4 and 5, the premarket-review stages, were set for three and a half and four years after publication.
• It did not change CLIA. The rule amended only the FDA’s own regulation at 21 CFR 809.3. It describes CLIA requirements, administered by CMS, as “complementary and distinct from FDA requirements.”
• It did not remove existing tests from use. Its policy for currently marketed tests stated the FDA generally did not intend to enforce premarket review for tests first marketed before the rule was issued and left unmodified.
• It did not apply to every laboratory test alike. The categories in section 5 remained largely or wholly under enforcement discretion.
• The compliance guide did not create binding rules. The June 2024 notice describes the guide as not binding on the FDA or the public.

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8. The 2025 Court Decision and the FDA’s Reversal

The FDA’s own Federal Register notice of 19 September 2025 records what happened. On 31 March 2025 the United States District Court for the Eastern District of Texas issued a final judgment in a case brought by a clinical-laboratory trade association against the FDA (No. 4:24-CV-479-SDJ), “vacating and setting aside the Rule and remanding the matter to the Secretary of Health and Human Services for further consideration.” To vacate a rule is to cancel it, so that it has no legal effect.

On 19 September 2025 the FDA published a final rule, “Medical Devices; Laboratory Developed Tests; Implementation of Vacatur” (90 FR 45134, FR Doc. 2025-18239, Docket No. FDA-2025-N-1730), removing the words “including when the manufacturer of these products is a laboratory” from 21 CFR 809.3(a) and reverting the statutory citation to section 201(h). It was effective the day it was published.

The FDA skipped public comment for this second rule, stating that “because the Rule has already been vacated, this action is ministerial in nature and merely removes text from the Code of Federal Regulations to reflect the court’s order.” The notice classifies the reversal as a deregulatory action under Executive Order 14192 and, reversing the 2024 estimates, reports annualized forgone benefits over 20 years of $3,723.39 million (7 percent discount rate) and annualized cost savings of $1,444.45 million, in 2024 dollars. It adds that portions of the uncertainty ranges overlap, “indicating the possibility of negative net benefits of the Rule and positive net benefits of its no longer being in effect.”

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9. Dates and Status as of 11 October 2026

• 3 October 2023: proposed rule published (88 FR 68006); comments closed 4 December 2023.
• 29 April 2024: final rule announced by FDA news release.
• 6 May 2024: final rule published (89 FR 37286).
• 25 June 2024: Small Entity Compliance Guide announced (89 FR 53109).
• 5 July 2024: rule effective.
• 31 March 2025: U.S. District Court for the Eastern District of Texas vacates the rule.
• 19 September 2025: FDA removes the added words from 21 CFR 809.3(a) (90 FR 45134), effective that day.

Legal status on 11 October 2026: vacated. The regulation text has been reverted to its pre-2024 wording since 19 September 2025. A check of the Federal Register through 11 October 2026 found no later FDA document on laboratory-developed tests after the September 2025 reversal.

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10. How the Rule Fits Earlier Actions

The documents place the rule in a longer history. The Medical Device Amendments of 1976, enacted on 28 May 1976, created the system of device classes and premarket review in the FD&C Act; the rule states that in implementing that law the FDA generally did not enforce its requirements for most LDTs, an approach that “developed as a matter of practice.” The rule notes that this general approach did not apply in every context — for example, not to LDTs used in declared emergencies under section 564 of the FD&C Act.

The rule states that the FDA “has long recognized the need for a change,” and that the history of its efforts on LDTs is described more fully in the October 2023 proposed rule. The 2024 final rule added the laboratory language to the regulation itself; the September 2025 vacatur rule returned the regulation to its earlier text, leaving the pre-2024 situation in place.

Among the other 2024 FDA actions on this site, the clearance of the first over-the-counter continuous glucose monitor is also a device decision from the FDA’s Center for Devices and Radiological Health, the center named as the contact office on the LDT rule.

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11. What Published Research Reports on Laboratory-Developed Tests

Published studies show both sides of the question the rule addressed. A 2018 comparison of 6,897 proficiency-testing responses for three cancer gene tests (BRAF, EGFR and KRAS) found that both LDTs and FDA-approved companion diagnostics exceeded 97 percent accuracy, with no consistent advantage for either; it also found that more than 60 percent of laboratories using an FDA-approved test had adapted it, which turned it into an LDT (Kim et al., 2018).

A 2023 review of LDTs used for cancer risk and early detection states that many LDTs enter the market without FDA or any regulatory review, and that CMS oversight under CLIA “focuses on analytic performance, but has limited oversight of the quality or utility of LDTs” (Offit et al., 2023). Reviews by laboratory physicians describe the legislative and regulatory history of LDT oversight and the content of the 2024 final rule (Genzen, 2019; Genzen et al., 2017; van Wijk et al., 2024; Genzen et al., 2025).

On the biotin example the rule cites, a 2022 review describes how high blood biotin can falsely raise results in competitive immunoassays and falsely lower them in sandwich immunoassays, with thyroid tests (free T3 and T4 raised, TSH lowered) the most common source of diagnostic error (Dasgupta, 2022). Biotin itself is described on the site’s Vitamin B7 (Biotin) page.

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12. Primary Documents

1. U.S. Food and Drug Administration (2024). FDA Takes Action Aimed at Helping to Ensure the Safety and Effectiveness of Laboratory Developed Tests. FDA News Release, 29 April 2024 — fda.gov press announcement
2. Food and Drug Administration, HHS (2024). Medical Devices; Laboratory Developed Tests. Final rule. Federal Register 89:37286, 6 May 2024, effective 5 July 2024. Docket No. FDA-2023-N-2177, RIN 0910-AI85 — FR Doc. 2024-08935
3. Food and Drug Administration, HHS (2024). Laboratory Developed Tests: Small Entity Compliance Guide; Guidance for Laboratory Manufacturers and Food and Drug Administration Staff; Availability. Notice. Federal Register 89:53109, 25 June 2024. Docket No. FDA-2023-N-2177 — FR Doc. 2024-13872
4. Food and Drug Administration, HHS (2025). Medical Devices; Laboratory Developed Tests; Implementation of Vacatur. Final rule. Federal Register 90:45134, 19 September 2025, effective 19 September 2025. Docket No. FDA-2025-N-1730 — FR Doc. 2025-18239

The proposed rule of 3 October 2023 (88 FR 68006) is cited in the final rule and is not separately linked here.

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Key Research Papers

1. Kim AS, Bartley AN, Bridge JA, Kamel-Reid S, Lazar AJ, Lindeman NI, et al. (2018). Comparison of Laboratory-Developed Tests and FDA-Approved Assays for BRAF, EGFR, and KRAS Testing. JAMA Oncology 4(6):838-841 — PubMed PMID: 29242895
2. Offit K, Sharkey CM, Green D, Wu X, Trottier M, Hamilton JG, et al. (2023). Regulation of Laboratory-Developed Tests in Preventive Oncology: Emerging Needs and Opportunities. Journal of Clinical Oncology 41(1):11-21 — PubMed PMID: 35944238
3. Genzen JR, Mohlman JS, Lynch JL, Squires MW, Weiss RL (2017). Laboratory-Developed Tests: A Legislative and Regulatory Review. Clinical Chemistry 63(10):1575-1584 — PubMed PMID: 28687634
4. Genzen JR (2019). Regulation of Laboratory-Developed Tests. American Journal of Clinical Pathology 152(2):122-131 — PubMed PMID: 31242284
5. van Wijk XMR, Master SR, Genzen JR (2024). FDA’s Final Rule on Laboratory Developed Tests. Clinical Chemistry 70(9):1192-1194 — PubMed PMID: 39222938
6. Genzen JR, Miller LJ, Rets AV, Affolter KE (2025). Laboratory-developed tests and in vitro diagnostics: A regulatory overview for anatomic pathology. American Journal of Clinical Pathology 163(5):730-743 — PubMed PMID: 39912823
7. Dasgupta A (2022). Immunoassay design and biotin interference. Advances in Clinical Chemistry 109:165-183 — PubMed PMID: 35953126

PubMed Topic Searches

1. PubMed: regulation of laboratory-developed tests
2. PubMed: accuracy of laboratory-developed tests
3. PubMed: biotin interference in immunoassays

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Connections

• FDA Actions of 2024
• FDA and Regulation
• Lab Tests
• Tumor Markers: What Cancer Blood Tests Can and Cannot Say
• Genetics and Imaging Tests
• Vitamin B7 (Biotin)
• First Over-the-Counter Continuous Glucose Monitor (2024)
• Talc Asbestos Testing Proposal (2024)
• Donanemab Alzheimer’s Approval (2024)

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