Jonathan Genzen, left, and Jonathan Carr sit in a studio.

Jonathan Genzen, MD, PhD (left), chief medical officer and senior director of governmental affairs, and Jonathan Carr, JD (right), compliance officer, prepare for ARUP’s webinar on the FDA’s proposed rule to regulate lab-developed tests.

November 30, 2023

ARUP Laboratories hosted a webinar for clients and members of the media on November 29 to answer questions about the FDA’s proposed rule to regulate laboratory-developed tests (LDTs) as medical devices. The rule would impose new clinical laboratory testing regulation that ARUP and industry partners oppose.

Jonathan Genzen, MD, PhD, ARUP’s chief medical officer and senior director of governmental affairs, started the hour-long presentation with background on the proposed rule and outlined ARUP’s main concerns, which include patient safety and access to critical tests.

Genzen explained ARUP’s objection to the FDA’s estimate of the purported financial benefits to society, saying the agency made a 250-fold error based on the company’s own analysis using information from the scientific literature. ARUP is also concerned about increased costs for patients, compliance costs for labs, and lengthy court proceedings if the rule is enacted and legally challenged, Genzen said.

After the presentation, Jonathan Carr, JD, ARUP’s compliance officer, joined Genzen and moderated the question-and-answer portion of the webinar, which included questions about lab tests for use in children. Genzen explained that most FDA-approved tests do not come with pediatric reference intervals, or ranges for normal results in children. Currently, PhD and MD scientists are permitted to validate age-appropriate reference intervals for assays used for pediatric testing in their labs.

“Most people wouldn’t consider a reference interval validation to be a modified FDA-cleared or -approved assay or LDT, but in this new FDA world, it might be, if it’s a change in intended use because pediatrics are not listed in the package insert,” Genzen said.

Other attendees asked about the performance of LDTs, which Genzen said in ARUP’s documented experience often outperform the FDA-approved assays. More sensitive LDTs are often used to confirm the presence of drugs of abuse, and Genzen said LDTs have played a critical role in addressing the opioid epidemic.

Genzen closed the webinar by encouraging attendees to submit their own comments to the FDA before the December 4 deadline and describing the timeline for potential implementation of the rule. By law, the FDA must respond to the comments, and that will take time, Genzen said. A final rule could be advanced as early as April.

Read ARUP’s public comment to the FDA here.

Submit public comment here.

Watch the webinar and view ARUP’s informational resources here.

Questions not addressed during the webinar due to time constraints will be answered on the web page mentioned immediately above within a few days.


Bonnie Stray,