A Winnipeg man who relies on blood donations to stay healthy is calling on fellow Manitobans to give, as Canadian Blood Services scrambles to deal with a shortfall in donations.

The agency says 252,000 Canadians have missed or cancelled their donation appointments so far this year, so it needs to book 78,000 appointments by the end of October to make up the shortfall and meet the anticipated demand.

Among those hoping more Manitobans will roll up their sleeves and donate is Ken Mason, who has variable common immunodeficiency, a disorder that impairs the immune system.

Mason depends on daily treatments, derived from donated blood, to fight off infection and keep him healthy. Without it, he can barely get out of bed, he said.

Officials with Canadian Blood Services say they are conducting research into why so many people are cancelling or missing their appointments, but one theory is that donors don't realize how important their donations really are.

To book an appointment with Canadian Blood Services, you can visit blood.ca or call 1-888-2-DONATE (1-888-236-6283). You can also use the free GiveBlood app, which is available for iOS and Android devices.