Summary: The U.S. Food and Drug Administration (FDA) finalized a rule regarding its oversight of laboratory-developed tests (LDTs) to make explicit that in vitro diagnostic products (IVDs) are considered devices under the Federal Food, Drug, and Cosmetic Act.


  1. The FDA’s final rule will categorize all in vitro diagnostic products as devices under the Federal Food, Drug, and Cosmetic Act, as a means to establish uniformity in how the products are regulated.
  2. The FDA will gradually eliminate its previous policy of enforcement discretion for LDTs, which historically allowed some labs to bypass certain regulatory requirements. 
  3. Despite the stricter regulations, the FDA says it intends to apply enforcement discretion selectively to prevent disruptions in patient care. 

The U.S. Food and Drug Administration (FDA) announced a final rule amending the FDA’s regulations to make explicit that in vitro diagnostic products (IVDs) are devices under the Federal Food, Drug, and Cosmetic Act (FD&C Act), including when the manufacturer of the IVD is a laboratory.

Along with this amendment, the FDA issued a policy to phase out, over the course of four years, its general enforcement discretion approach for laboratory-developed tests (LDTs). The agency also issued targeted enforcement discretion policies for certain categories of IVDs manufactured by laboratories.

“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,” says FDA Commissioner Robert M. Califf, MD. “The final rule announced today aims to provide crucial oversight of these tests to help ensure that important health care decisions are made based on test results that patients and health care providers can trust.”

Further reading: Clinical Labs Say FDA’s LDT Rule Would Hinder Pediatric Care

The FDA’s History of LDT Oversight

The FDA says that while it has generally exercised enforcement discretion for most LDTs—meaning that the agency generally has not enforced applicable requirements with respect to most LDTs—the risks associated with most modern LDTs are much greater than the risks associated with LDTs used when the FDA’s enforcement discretion approach was first adopted

“At that time, many LDTs were lower risk, small volume and used for specialized needs of a local patient population,” the FDA says in a new release. “Now, many LDTs are used more widely, for a larger and more diverse population, with large laboratories accepting specimens from across the country. LDTs also increasingly rely on high-tech instrumentation and software, are performed in large volumes and are used more frequently to help guide critical health care decisions.”

Moreover, the FDA claims there is a growing body of evidence that demonstrates that some IVDs offered as LDTs raise public health concerns.

Further reading: Labs Express Concern about Testing Access if FDA Regulates LDTs

The FDA Claims Need for More IVD Oversight

The FDA says it 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, according to the administration.

The FDA says that without greater oversight of the safety and effectiveness of LDTs, patients may be more likely to initiate unnecessary treatment, or delay or forego proper treatment based on inaccurate test results.

Further reading: Is There a Balancing Point for LDT Regulations?

Impact of the FD&C Act

Increased compliance with device requirements under the FD&C Act—such as premarket review, quality system (QS) requirements, adverse event reporting, establishment registration and device listing, labeling requirements, and investigational use requirements—seeks to put patients and health care providers in a better position to have confidence in IVDs regardless of where they are manufactured. 

With increased oversight, the FDA says it hopes to promote adequate representation in validation studies, as well as transparency regarding potential differential performance and unknown performance in certain patient populations.

“Today’s action is a critical step toward helping to ensure the safety and effectiveness of LDTs, while also taking into account other public health considerations, including continued access to critical tests patients rely upon,” says Jeff Shuren, MD, JD, director of the FDA’s Center for Devices and Radiological Health. “Through targeted enforcement discretion policies for certain categories of tests manufactured by a laboratory, we expect patients and health care professionals will continue to have access to the tests they need while having greater confidence that the tests they rely on are accurate.”

FDA’s Change in LDT Oversight

The phaseout of the FDA’s general enforcement discretion approach for LDTs over a period of four years aims to help assure the safety and effectiveness of these tests while avoiding undue disruption to patient care, according to the administration.

“Importantly, the FDA considered the large volume of comments received on the notice of proposed rulemaking, and in light of that input, has adjusted the phaseout policy in a manner that better serves the public health,” the FDA says. “After this phaseout, the FDA generally will expect IVDs made by either a non-laboratory or laboratory to meet the same requirements, though certain IVDs manufactured by laboratories may fall within one of the agency’s targeted enforcement discretion policies.” 

The FDA says it intends to exercise enforcement discretion with regard to premarket review and most quality system requirements for certain categories of IVDs, including but not limited to:

  • Currently marketed IVDs offered as LDTs that were first marketed prior to the date of issuance of the final rule. This enforcement discretion 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.
  • LDTs manufactured and performed by a laboratory integrated within a health care system to meet an unmet need of patients receiving care within the same health care system when an FDA-authorized test is not available. This enforcement discretion policy is intended to help avoid patients being deprived of critically needed LDTs where certain risk mitigations exist that may help laboratories to identify any problems with their LDT and may help inform appropriate use and interpretation of such LDTs.

The FDA has also included additional enforcement discretion policies, such as for LDTs approved by the New York State’s Clinical Laboratory Evaluation Program (CLEP), as described in the preamble to the final rule, where that program’s review of analytical and clinical validity helps to mitigate the risk of harm from inaccurate and unreliable LDTs. 

Draft Guidance Documents

The agency also issued two draft guidances today. One provides the agency’s thinking about an enforcement discretion policy for certain laboratories offering certain unauthorized IVDs for immediate response to an emergent situation, such as an outbreak of an infectious disease, in the absence of a declaration applicable to IVDs under section 564 of the FD&C Act. The other provides insight into the FDA’s thinking about the factors the agency intends to consider when developing a policy regarding enforcement discretion for certain IVDs during a public health emergency declared under section 564 of the FD&C Act.