OTTAWA — Canadian Blood Services has told 2,400 women that as of this
week, they can no longer donate a blood component that is vital in treating
cancer patients.
Platelets, fragile cell fragments found in whole blood that are essential to
clotting, are in high demand, in part because they cannot be stored for more
than a week. But in a letter sent earlier this month, Canadian Blood Services
told its female platelet donors who have been pregnant even once that they can
no longer give platelets because their donations may contain antibodies that
trigger a rare, but potentially fatal, transfusion complication.
According to the blood agency, the chances of a transfusion recipient developing
Transfusion Related Acute Lung Injury — or TRALI — are one in 5,000. Of those
cases, five to 10 per cent will be fatal. In Canada, the health system
identified as many as four cases a year where TRALI was a contributing factor
to, but not necessarily the cause of, death.
Platelets are needed to treat patients with prolonged bleeding associated with
some diseases. In particular, they are used to treat cancer patients whose bone
marrow has been compromised either by the disease itself or by certain
chemotherapy drugs, and can no longer produce platelets.
"The risk of not having a platelet transfusion when you need it is far greater
than the risk of TRALI," said Dr. Heather Hume, the executive medical director
of transfusion medicine for Canadian Blood Services.
But the tainted-blood scandal that resulted when thousands of Canadians were
infected with HIV or hepatitis C through transfusions in the 1980s and 1990s has
led to better screening procedures of the blood supply, and much stricter rules
on who is allowed to donate.
"There’s no doubt, as a worldwide community, we pay much greater attention to
small risks than was the case 30 years ago" said Hume.
But, she added, just because the chances of a transfusion recipient developing
TRALI are small, "that doesn’t mean that we shouldn’t try to do something to
make it happen even less often.
"We’ve tried to keep our supply up and decrease our risk of TRALI, but it is a
constant balancing act."
As of June, there were 6,768 platelet donors in Canada — 2,400 of them women who
have been pregnant at least once.
The chances of developing the harmful antibodies increases with each pregnancy,
even if it ends prematurely. Studies have shown that after two pregnancies,
one-quarter of women carry the potentially harmful antibodies.
But Hume said that these numbers don’t tell the whole platelet supply story.
For one thing, 82 per cent of donations are from men, who give more frequently
than women.
As well, women who have never been pregnant — about one-third of all female
donors — can still donate.
That leaves a shortfall of 12 per cent of donations, "which is not
insignificant," said Hume. But some of the shortage has been made up with new
technology that allows eligible donors to give a greater number of platelets in
one sitting.
Canadian Blood Services has also been working to recruit more men to give
platelets.
"We will be watching very carefully, but we are anticipating that it will not
affect the supply," said Hume.
Source : Canwest News Service
