Anyone who has ever gotten a medical test – to detect cancer, determine fetal health or even figure out food allergies - may want to pay close attention to a controversy on  display in Washington Friday.

The debate pivots on whether the U.S. Food and Drug Administration should regulate a subset of diagnostic tests they have long exempted from oversight. As long as these tests are designed, manufactured, and used within a single laboratory, they can be sold without FDA approval.

Once, these tests - known as laboratory-developed tests - comprised a small percentage of all tests and were often developed and used in hospitals or similar settings. Many were variations on common tests or developed for very rare conditions.

But today, for-profit companies are using the exemption to market a growing number of ever more complex tests to diagnose a myriad of medical conditions. The FDA estimates there are about 11,000 of these tests offered by about 2,000 labs. I recently wrote about serious concerns from unregulated  prenatal screening tests and  Lyme disease tests.

The FDA announced several months ago they would phase in regulation of the tests over nine years. Today is the second day of a two-day FDA hearing on that proposal.

The debate is passionate – the chief executive of ARUP Laboratories in Utah reportedly received a standing ovation Friday when he called the FDA’s proposed recommendations dangerous and misguided. Other participants, from the Infectious Diseases Society of America to the Mayo Clinic, said the proposed oversight will harm patients, be prohibitively expensive and stifle innovation in developing critically important tests.

In a statement released this week, Steve Rusckowski, chairman of the American Clinical Laboratory Association (ACLA) board of directors and chief executive of Quest Diagnostics, urged the FDA to not regulate. “In the interest of patients and their continued access to critical laboratory testing services, it is incumbent upon the FDA to reverse course and withdraw its proposed agency overreach,” Rusckowski said.

The  Washington-based ACLA also released a white paper this week written by Harvard Law professor Laurence Tribe and former Solicitor General Paul D. Clement detailing why the FDA does not have the authority to regulate the tests. Yet there are equally strident calls for oversight.

Laura Koontz of the Ovarian Cancer National Alliance Friday urged the FDA to regulate, noting that patients need to be assured tests really do what they promise. She referenced an early-detection cancer test in 2008 that incorrectly diagnosed women with ovarian cancer.

That laboratory-developed test, OvaSure, has since been taken off the market.  Some women had unnecessary surgery, going into early menopause, among other health effects, Koontz said.

“This isn’t a hypothetical example,’’ said Koontz, the Alliance’s director of policy. “We would love to see new tests reach the market…but these tests must be validated to ensure they are safe, reliable and effective.”

Also this week, the Journal of the American Medical Association published two editorials laying out arguments for and against regulation. Joshua Sharfstein associate dean for public health practice and training at the Johns Hopkins Bloomberg School of Public Health, argued oversight was critical.

“A patient travels by an ambulance that is regulated, to a hospital that is regulated, for care using medicines that are regulated, administered by nurses and physicians, who are regulated. Yet today, that same patient’s life or death could hinge on whether a single, unregulated diagnostic test result is meaningful,” Sharfstein wrote.

“The FDA is right to bring a measured approach to ensuring the quality, safety, and validity of laboratory-developed tests.”