Introduction to the LDT Final Rule

Understanding the New Landscape for Lab Developed Tests

by t_king

On May 6, 2024, the FDA officially published the Lab Developed Test (LDT) Final Rule, marking a significant shift in the regulatory landscape for laboratory tests. This rule, which comes into effect on July 5, 2024, brings substantial changes, and it’s crucial for everyone involved in the laboratory testing field to understand its implications. While challenges to this rule are anticipated, the publication of the final rule signifies a new era in the regulation of LDTs.

In this blog series, we’ll break down the LDT Final Rule, explore its impact on various stakeholders, and provide guidance on navigating these changes. But first, let’s dive into the key points of the LDT Final Rule and what it means for the industry.

Key Points of the LDT Final Rule

FDA Classification of LDTs as IVDs

The FDA now classifies LDTs as In Vitro Diagnostics (IVDs), extending its oversight to these tests. This means LDTs will be subject to the same stringent requirements as other IVDs, including registration, adverse event reporting, and validation.

Changes to the Definition of IVDs

A significant change in the regulation is the amendment to the definition of IVDs in 21 CFR Part 809.3(a). The definition now explicitly includes IVDs manufactured by laboratories. This codification clarifies that tests developed by laboratories are considered IVDs under the law.

These changes are expected to have widespread effects across the industry, particularly impacting CLIA labs, IVD manufacturers, and RUO (Research Use Only) manufacturers. Understanding these impacts is crucial for compliance and operational planning.

The Impact on Different Stakeholders

Impact on CLIA Labs

The most significant impact of the LDT Final Rule will be felt by CLIA labs. These laboratories will face increased operational costs due to the need for compliance with new quality system regulations and enhanced validation efforts for LDTs. Moreover, CLIA labs may no longer be able to use RUO/IUO (Investigational Use Only) reagents to validate their LDTs, adding another layer of complexity.

Impact on IVD Manufacturers

For IVD manufacturers, the primary concern is the potential increase in turnaround times for FDA reviews. Given the FDA’s limited bandwidth, the review process might slow down, affecting the timely approval of new products.

Impact on RUO Manufacturers

RUO manufacturers will also experience significant changes. With new limitations on selling to clinical laboratories, RUO manufacturers may need to undergo FDA submissions for their reagents and components, potentially requiring the creation of device master files.


The LDT Final Rule represents a transformative change in the regulation of laboratory tests. Understanding its key points and the impacts on different stakeholders is the first step in navigating this new regulatory environment. In our next blog post, we will delve deeper into the specific impacts on CLIA labs and provide actionable strategies for compliance.

Stay tuned for more insights and guidance on how to adapt to the LDT Final Rule.