Shortages of technetium Tc-99m had clinical impact — it drove up usage of cardiac catheterization to measure exercise stress, according to a recently published report.
“Shortages of important medical compounds can have substantial clinical consequences,” researcher Dr. Venkatesh L. Murthy from the University of Michigan in Ann Arbor reported to Reuters
. In a study of the use of technetium 99m (Tc-99m ) during the 2010-2012 period based on Medicare data, a shortage of the radioisotope at the time “appears to have led to a nearly 10 percent increase in heart catheterizations after stress tests,” he told the news agency.
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The study determined that there were over 5,700 extra cardiac catheterizations for the patients in the study. Technetium 99m use dropped almost 25 percent during that period.
“In this particular case, shifting to thallium-201 during future shortages of technetium-99m may not be the optimum strategy, and greater use of other tests, such as positron emission tomography (PET), magnetic resonance imaging (MRI) and computed tomography (CT), may be a better alternative,” he advised.
The production challenge is well-known in the industry. Technetium Tc 99m is made largely from "weapons-grade" highly-enriched uranium, according to the study published online in JAMA Cardiology
, which noted that “none of the nuclear reactors that produce molybdenum Mo 99, the parent isotope of Technetium Tc 99m, are located in the United States and all are at least 50 years old, with repeated shortages of Technetium Tc 99m occurring, owing to required repairs.”
As HCB News reported in June
, the U.S. government has an “interest” in “ensuring a reliable supply” of molybdenum 99 (Mo-99), according to an address by Dr. Matt Heavner, Ph.D., assistant director for global security for the White House Office of Science and Technology Policy, at the San Diego SNMMI meeting.
“Even though the health of Americans relies heavily upon the availability of this isotope … there have been times in recent years when it has been in short supply,” he acknowledged to the SNMMI attendees.
Part of the challenge is that the materials used to make it carry weapons risks. Regarding these, Francie Israeli, press secretary with the National Nuclear Security Administration (NNSA) told HCB News, “Current supply challenges derive from two types of problems … Mo-99 production facility outages and problems associated with transporting Mo-99 from production facilities to Tc-99m generator producers – particularly across international borders.”
One way to combat the proliferation risks is the government-advocated switch to the use of low-enriched uranium (LEU) for production. “In the case of medical isotope production this has not been a trivial matter,” said Israeli. “These issues are being successfully addressed by current producers who are expected to complete conversions over the next three years.”
LEU and HEU production methods produce clinically equivalent Mo-99, she told HCB News.
The scope of the challenge to switch was also noted by the researchers in the JAMA report. “There are efforts to address this issue by many groups,” Murthy said. “Several companies have developed technologies to produce the technetium without using weapons-grade uranium. What is not completely clear yet is whether they will be able to operationalize these technologies and ramp up supply quickly enough.”