Stephen Littlejohn (right), a vice president of Covidien's pharmaceuticals segment, is hesitant to describe the current shortage as a crisis. "But I think it has been a very challenging situation," he said.

Covidien, headquartered in Dublin, has approximately 3,000 employees in the St. Louis-area.

Poland's Maria Reactor will produce Molybdenum 99 (Mo 99), which is used to make Technetium 99m (Tc 99m), a radioisotope used by doctors to detect tumors and organ abnormalities. The Covidien plant in Maryland Heights supplies all the Tc 99m generators in the United States, Canada, Latin America and some countries in the Pacific Rim.

Photo provided by Covidien

Poland's Maria reactor

At the time of last week's announcement, five nuclear reactors worldwide were producing Mo 99 -- none based in the U.S. One site in Canada has been shut down for almost a year, and another, in the Netherlands, stopped production last week for six months of upcoming repairs.

The three remaining active reactors supplying Covidien with Mo 99 are in Belgium, France and South Africa.

When Tc 99m is introduced to a patient's body it gives off a color signature that can be detected by cameras to locate trouble spots, such as tumors or areas of constricted blood flow.

With a relatively short half-life of around six hours after its generation, it is preferred by most physicians over longer lasting isotopes. A half-life is the amount of time required for half of an original sample to decay; a shorter half-life means patients endure less exposure to radiation.

"It's a radioactive isotope that has a very nice combination of properties," said Dr. Barry Siegel (right), chief of the Division of Nuclear Medicine (Mallinckrodt Institute of Radiology) at Washington University.

The shortage of Tc 99m has resulted in difficulties for local doctors and hospitals.

"We are going to start having shortages by the end of this week," said Siegel. "A lot of worldwide clinical nuclear medicine requires this isotope. Eighty percent of the things we do today are done with it. So it's been a cornerstone product."

Photo provided by Covidian

 A single-photon emission computerized tomography (SPECT) scan

Siegel said Covidien has been open with professionals about the shortage. He added that doctors might have to revert to older processes to continue treatments. "This is not going to be optimal for patient care," he said.

(For a link to a Covidien letter to doctors and hospitals addressing the shortage in a color-coded format, click here.)  

Littlejohn said his company has issued color-coded calendars to keep clients informed of supply and to help them plan ahead. "The point of these (calendars) is to be as transparent and as open as we can," he said. Littlejohn said doctors have been encouraged to use the Tc 99m conservatively and administer it to patients on a "just-in-time basis" to maintain its effectiveness.

"I hope that the gloom and doom period will not be as long as some think," Siegel said. "But we nonetheless have to plan for the worst-case scenario. I am giving this a day-by-day attack plan."