A laboratory developed test (LDT) is a type of in vitro diagnostic test that is designed, manufactured and used within a single laboratory.

LDTs can be used to measure or detect a wide variety of analytes (substances such as proteins, chemical compounds like glucose or cholesterol, or DNA), in a sample taken from a human body. Some LDTs are relatively simple tests that measure single analytes, such as a test that measures the level of sodium. Other LDTs are complex and may measure or detect one or more analytes. For example, some tests can detect many DNA variations from a single blood sample, which can be used to help diagnose a genetic disease. Various levels of chemicals can be measured to help diagnose a patient’s state of health, such as levels of cholesterol or sodium.

While the uses of an LDT are often the same as the uses of FDA-cleared or approved in vitro diagnostic tests, some labs may choose to offer their own test. For example, a hospital lab may run its own vitamin D assay, even though there is an FDA-cleared test for vitamin D currently on the market.

The FDA does not consider diagnostic devices to be LDTs if they are designed or manufactured completely, or partly, outside of the laboratory that offers and uses them.

LDT’s are important to the continued development of personalized medicine, so it is important that in vitro diagnostics are accurate so that patients and health care providers do not seek unnecessary treatments, delay needed treatments, or become exposed to inappropriate therapies.

FDA Activity

The FDA has generally not enforced premarket review and other applicable FDA requirements because LDTs were relatively simple lab tests and generally available on a limited basis. Due to advances in technology and business models, LDTs have evolved and proliferated significantly since the FDA first obtained comprehensive authority to regulate all in vitro diagnostics as devices in 1976. Some LDTs are now much more complex, have a nationwide reach and present higher risks, such as detection of risk for breast cancer and Alzheimer’s disease, which are similar to those of other IVDs that have undergone premarket review.

The FDA has identified problems with several high-risk LDTs including: claims that are not adequately supported with evidence; lack of appropriate controls yielding erroneous results; and falsification of data. The FDA is concerned that people could initiate unnecessary treatment or delay or forego treatment altogether for a health condition, which could result in illness or death. The FDA is aware of faulty LDTs that could have led to: patients being over- or undertreated for heart disease; cancer patients being exposed to inappropriate therapies or not getting effective therapies; incorrect diagnosis of autism; unnecessary antibiotic treatments; and exposure to unnecessary, harmful treatments for certain diseases such as Lyme disease.

In 2010, the FDA announced its intent to reconsider its policy of enforcement discretion for LDTs and held a workshop to obtain input from stakeholders on such policy. FDA used this feedback to develop an initial draft approach for LDT oversight and published draft guidance in 2014. FDA solicited feedback on on the draft LDT framework and notification guidances as well as held a public workshop.

In gathering feedback on the LDT draft guidances issued in 2014, we continuously engaged with interested stakeholders, including those groups that authored alternative proposals. We analyzed more than 300 sets of comments on the draft guidances and discussion from a subsequent public workshop held in 2015 as well as engaged in many meetings and conferences with various stakeholders. In the absence of issuing final guidance and at the request of stakeholders, we feel it is our responsibility to share our synthesis of all the feedback we have received, with the hope that it advances public discussion on future LDT oversight.

To this end, on January 13, 2017, the FDA issued a discussion paper on LDTs. The synthesis does not represent the formal position of FDA, nor is it enforceable. We hope to simply advance the public discussion by providing a possible approach to spur further dialogue.

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LDT Safety Information

• The Public Health Evidence for FDA Oversight of Laboratory Developed Tests: 20 Case Studies – The real and potential harms to patients and to public health from certain laboratory developed tests (LDTs) – November 16, 2015

LDT Public Workshops & Committees

• Public Workshop – Oversight of Laboratory Developed Tests, July 19-20, 2010

Reports to Congress

• Notification to Congress: FDA’s Laboratory Developed Tests Framework – July 31, 2014 (PDF - 991KB)

Related Links

• Blueprint for Breakthroughs - Charting the Course for Precision Medicine
• FDA Discussion Paper on Laboratory Developed Tests (LDTs) (PDF - 180KB)
• FDA - Personalized Medicine