Matter of fact
New York:
The oldest blood available for transfusions releases large and potentially
harmful amounts of iron into patients' bloodstreams, warns a new study which
recommends reducing the maximum storage limit of red blood cells from six to
five weeks.
Researchers at Columbia University Medical Centre (CUMC) in the US
randomly assigned a group of 60 healthy volunteers to receive a unit of red
blood cells that had been stored for one, two, three, four, five or six weeks.
The volunteers were then monitored
for 20 hours after transfusion. Within hours after transfusion, seven of the
nine volunteers who received the six-week-old blood could not appropriately
metabolise the damaged cells, thereby releasing large amounts of iron into
their bloodstream. Only one volunteer who received younger blood had a similar
response, with blood had been stored for five weeks.
“Our recommendation will be controversial,
but we think we have real data to support it,” said Steven Spitalnik from CUMC.
“Recent studies have concluded that
transfusing old blood has no impact on patient outcomes, but those studies did
not exclusively examine the oldest blood available for transfusions. Our new
study found a real problem when transfusing blood that is older than five
weeks,” said Spitalnik.
“However the longer you store blood,
the more the cells become damaged,” said Eldad Hod, associate professor at
CUMC.
Currently, the US Food and Drug
Administration (FDA) allows units of red blood cells to be stored for up to six
weeks before they must be discarded.
None of the volunteers were harmed by
the transfusion, but previous studies have shown that excess iron can enhance
blood clots and promote infections.
“Based on the amount of iron
circulating in the blood of the volunteers who received six-week-old blood, we
had predict that certain existing infections could be exacerbated,” said Hod.
“Thus, for ill, hospitalised
patients, this excess iron could lead to serious complications,” said
Spitalnik.
The true impact of six-week-old blood
on the rate of complications in patients is likely to be small, said the
researchers.
“It is estimated that up to 10 to 20
per cent of blood units used for transfusions have been stored for more than
five weeks, so the number of patients who are likely to receive a unit of very
old blood is substantial,” said Hod.
The study appears in the Journal of
Clinical Investigation.
Source: DNA-12th January,2017
