Laboratory developed test definition: what is an LDT?

Aaron Hoare Date published: Jul 09, 24

A laboratory developed test (LDT) is a type of diagnostic test that is designed, manufactured and used within a single laboratory. Unlike tests that are commercially distributed, laboratory developed tests are tailored to meet specific needs based on the laboratory's own expertise and the unique requirements of its clientele.

These tests play a pivotal role in the field of personalized medicine, allowing for precise diagnostics that adhere to stringent analytical standards. Laboratory developed tests also facilitate the rapid incorporation of scientific advancements into clinical practice, enabling healthcare providers to offer cutting-edge solutions that can significantly impact patient outcomes.

Laboratory developed tests serve as a cornerstone in the progression of diagnostic and personalized medicine. Their critical role spans numerous facets, including enhancing diagnostic accuracy, fostering innovation in medical research and enabling tailored therapeutic strategies. Through the bespoke nature of lab developed tests, laboratories can focus on niche areas and rare conditions that might not be addressed by commercially available tests.

This specialization ensures that patients receive the most accurate and relevant diagnostic information, ultimately guiding more effective and individualized treatment plans. Furthermore, LDTs are at the forefront of integrating emerging scientific discoveries into clinical settings, often translating groundbreaking research into practical diagnostics faster than traditional commercial mechanisms. The flexibility and rapid adaptability of laboratory developed tests not only improve patient care but also drive the evolution of medical science by constantly pushing the boundaries of what is diagnostically possible.

Want to learn more about LDTs?

Download our free deep dive whitepaper on the future of LDTs and more information on FDA’s 2024 final ruling on lab developed tests.

Download now

In vitro diagnostics and laboratory developed tests

In the realm of in vitro diagnostics (IVDs), laboratory developed tests have a unique regulatory framework. According to the FDA, LDTs are a subset of IVDs designed, manufactured and used within a single clinical laboratory. This contrasts with traditional IVDs, which undergo a more comprehensive regulatory approval process for commercial distribution. As a result, lab developed tests often face less rigorous pre-market scrutiny, allowing for greater flexibility and innovation. However, they must still adhere to stringent quality control measures under the Clinical Laboratory Improvement Amendments (CLIA).

The FDA recognizes the crucial role LDTs play in advancing personalized medicine and addressing unmet medical needs. Yet, the agency stresses the importance of ensuring these tests meet high standards of accuracy, reliability and clinical validity. Recent discussions highlight the potential for increased regulatory oversight to balance innovation with patient safety. This ongoing dialogue underscores the dynamic nature of LDT regulation, as stakeholders strive to optimize the balance between medical advancements and stringent patient protection standards.

Organizations and labs performing laboratory developed tests

Laboratory developed tests are crafted by a wide range of specialized organizations and laboratories. Academic medical centers, leveraging their extensive research capabilities and clinical expertise, create lab developed tests for complex and rare medical conditions. These centers operate at the cutting edge of medical science, ensuring their diagnostic tests incorporate the latest advancements.

Reference laboratories, known for high-throughput and specialized testing services, handle large volumes of samples with precision and reliability. This makes them ideal for developing laboratory developed tests that require advanced analytical methods and instrumentation.

Biotechnology companies and startups play a significant role in the laboratory developed test landscape by focusing on niche markets and novel diagnostic platforms. Their agility and emphasis on innovation enable them to quickly translate scientific discoveries into practical diagnostic tools.

Large hospital laboratories and healthcare systems use lab developed tests to enhance patient care. By creating custom tests tailored to their patient populations, these entities offer highly specific and timely diagnostic information, improving clinical decision-making and patient outcomes. Through their integration with clinical services, hospital laboratories ensure laboratory developed tests are seamlessly incorporated into the broader healthcare framework.

Together, these diverse organizations and labs advance diagnostic testing, continuously pushing the boundaries of what is possible through innovative LDTs.

Standards and regulations applicable to labs carrying out laboratory developed tests

Laboratories that develop and implement laboratory developed tests operate within a framework of rigorous standards and regulations designed to ensure the quality, accuracy and reliability of their diagnostic tests. These regulations are multi-faceted, encompassing various aspects of laboratory operation and test development.

Clinical Laboratory Improvement Amendments (CLIA)

In the United States, the Clinical Laboratory Improvement Amendments provide the primary regulatory standards for all clinical laboratory testing performed on humans, including LDTs.

CLIA were enacted by the United States Congress in 1988. This legislative move responded to growing concerns about the variability and quality of laboratory testing across the country. Before CLIA, there were significant discrepancies in the standards governing clinical laboratories, which sometimes led to incorrect diagnoses and suboptimal patient care.

Food and Drug Administration (FDA)

Although traditionally laboratory developed tests have not been subject to the same pre-market approval process as commercially distributed tests, the Food and Drug Administration (FDA) has asserted its authority to regulate LDTs under the Medical Device Amendment Act. The FDA's oversight primarily focuses on ensuring that lab developed tests meet safety, effectiveness and performance standards. The FDA has been working on establishing a risk-based regulatory framework for LDTs, where tests that pose higher risks to patients could be subject to more stringent regulatory requirements, such as pre-market review and post-market surveillance.

Ethical and best practice guidelines

Beyond formal regulatory requirements, laboratories also adhere to ethical and best practice guidelines established by professional organizations such as the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP). These guidelines offer recommendations on best practices for developing laboratory developed tests.

International Organization for Standardization (ISO)

Internationally, the International Organization for Standardization (ISO) sets globally recognized standards that can be integral to laboratory operations. ISO 15189 is particularly relevant for medical laboratories, specifying requirements for quality and competence in medical laboratories.

By adhering to ISO standards, laboratories that perform lab developed tests not only demonstrate their commitment to operational excellence, but also ensure that their diagnostic tests are conducted under rigorous quality control mechanisms. This adherence to international standards of quality propels the continual advancement of laboratory practices, promoting confidence in diagnostic accuracy and patient safety globally.

Relevant ISO standards for laboratories performing LDTs

ISO 9001

ISO 9001:2015 outlines criteria for a quality management system and is applicable to any organization, regardless of its type or size. For medical laboratories, adoption of ISO 9001:2015 ensures a holistic approach to quality management by emphasizing customer satisfaction, continuous improvement and regulatory compliance.

ISO/IEC 17025

ISO 17025:2017 focuses on the general requirements for the competence of testing and calibration laboratories. While it is applicable across various types of laboratories, including those involved in medical testing, it provides stringent guidelines for developing protocols, conducting method validations and implementing quality management systems. Laboratories that comply with ISO 17025:2017 demonstrate their technical proficiency and reliability in producing precise and accurate testing results.

ISO 13485

ISO 13485:2016, though primarily relevant to the producers of medical devices, is crucial for laboratories involved in the development of diagnostic tests, particularly where those tests involve the creation or use of diagnostic medical devices.

Importance of a quality management system in compliant LDT practices

A robust Quality Management System (QMS) is fundamental for laboratories performing laboratory developed tests to maintain compliance with stringent regulatory standards and enhance operational excellence. A well-implemented QMS ensures that all aspects of laboratory operations are systematically managed and continuously improved. By adhering to a QMS, laboratories can ensure the consistency, accuracy and reliability of their diagnostic tests, which is crucial for patient safety and effective clinical decision-making.

Moreover, a comprehensive QMS provides a structured framework for regulatory compliance, helping laboratories to meet the requirements of CLIA, FDA, CAP, ISO standards and other relevant guidelines. This includes rigorous documentation practices, internal audits, corrective and preventive actions (CAPA) and continuous monitoring of test performance. An exemplary QMS not only satisfies regulatory demands but also fosters a culture of quality and accountability within the laboratory, driving continual improvement and operational efficiency.

More on FDA's final rule

Watch our webinar with regulatory attorney, Christine Bump, who is a specialist on the topic as she sheds light on exactly what FDA’s final rule could mean for your lab.

Watch the webinar