OTTAWA - Clinics are paying two to three times more for medical isotopes after a supplier abruptly hiked its prices this month - just before the Chalk River reactor shut down and caused an isotope shortage.

Doctors fear the higher costs may force some clinics to delay tests used to detect cancer and heart ailments, lay off staff or even close.

Lantheus Medical Imaging, a Massachusetts-based company that supplies clinics with 'generators' used in medical imaging, notified its customers last week of the price increase.

The Canadian Press obtained a letter Lantheus sent its customers on May 11 saying it had to raise prices after one of its suppliers started charging more for the isotope molybdenum 99, or Mo-99.

"Over the past several months, we have been engaged in negotiations of a new contract with one of our Mo-99 suppliers," the letter says.

"Unfortunately, that supplier has demanded pricing two to three times higher than what we have been paying under our most recent agreement. ...

"Considering the magnitude of the molybdenum increase, we will have no choice but to implement a weekly surcharge."

Lantheus's supplier buys raw isotopes from Atomic Energy of Canada Ltd. The supplier then sells those Mo-99 isotopes to Lantheus, which makes the lead-lined generators that hospitals receive.

Physicians then run the generators through a process that produces another isotope, which is injected into the body to help radiologists in their diagnoses.

Lantheus did not name its supplier in the letter.

But a government document obtained by The Canadian Press shows Ottawa-based MDS Nordion was - until Wednesday - Lantheus' sole supplier of Mo-99 isotopes.

In late January, a senior bureaucrat at Natural Resources Canada travelled to Paris to give a slideshow presentation to the Nuclear Energy Agency.

A graphic in the presentation by Serge Dupont, associate deputy minister of NRCan, shows Lantheus received its entire Mo-99 isotope supply from MDS Nordion.

Earlier Wednesday, a spokesman for AECL also confirmed that MDS Nordion is Lantheus's only supplier of isotopes. "That would be MDS," Dale Coffin said.

Coffin also confirmed that AECL has not raised the price of the isotopes it supplies to MDS Nordion.

Lantheus and MDS Nordion wouldn't comment on their supply agreement.

An MDS Nordion spokeswoman said in an email the company "has taken no pricing actions related to the current NRU shutdown."

The price increase comes as AECL shut down an aging nuclear reactor at Chalk River, Ont., that provides up to half the global supply of isotopes used in medical imaging.

The Crown corporation estimates the reactor will be out of service for more than a month while a heavy-water leak is repaired.

AECL says it has enough medical isotopes for the coming week, but won't be able to meet demand by the weekend.

Dr. Christopher O'Brien, president of the Ontario Association of Nuclear Medicine, said an isotope price hike coupled with a supply shortage will pinch clinics.

"This is of extreme concern to us," he said.

"We are potentially looking at small hospital closures, job losses, technologists, nurses being fired ... reduced patient access because the money's not there now to buy the stuff."

O'Brien said clinics began paying more for isotopes at the beginning of May.

He said he recently emailed Health Canada warning the added cost to clinics could range from $80,000 to $200,000 a year, depending on their size and how busy they are.

"This is equivalent to having no molybdenum, because the impact is the same where you'll have to reduce access, not based on unavailability of isotopes, but based on inability to pay for isotopes," he said.

"So the effect is still the same."

Natural Resources Minister Lisa Raitt, in Edmonton for a luncheon talk, said she is concerned about the added costs to clinics.

"It is of concern as to the cost associated with producing the isotope as compared to what the end cost is to the user," she said.

"It's noted by me that there is an increase in the amount with respect to the isotope, but it's something that really is in the private domain."

Meanwhile, Lantheus announced a deal Wednesday with a subsidiary of the South African Nuclear Energy Corp. to supply it with isotopes.

A spokeswoman for Lantheus said in an email the company "will continue to receive supply from our primary supplier in addition to this new weekly Mo-99 supply."