Demand for blood plasma is increasing each year, and the blood service says it needs more donors to keep up.
It's calling on blood donors to switch from giving whole blood to plasma.
Brendan Judd likes to bring cakes to his local donation centre to say thank you. At just nine, he's already received 450 plasma donations.
He has almost no immune system and relies on other people's antibodies to keep him healthy.
"I don't know how it works, but it does stop me getting sick," says Brendan.
By the age of three he'd had bacterial meningitis twice and septicaemia four times. He now has plasma transfusions every six days, and mum Rachel says it's saved his life.
"We haven't had a hospital admission since he started his therapy," she says. "He's a normal kid. He can run around and do everything he wants to do."
Plasma is used for accident victims and during surgery, but it can also now be used to make 13 different life-saving products for cancer patients, burns victims and people with bleeding disorders or poor immune systems. It's quite literally liquid gold.
An apheresis machine takes the blood, separates out the plasma, then returns the rest of the blood back to the donor -- people like Michael Bain, who's making his 100th donation today.
"It's just a matter of wanting to give back," says Mr Bain. "There are people that are in need and I've got a lot of blood, a lot of plasma to give, so why not?"
There are currently 9000 plasma donors across the country, but the demand for plasma is increasing by 13 percent a year and the Blood Service says it needs another 2400 donors to keep up.
"We are encouraging people, if they can, to consider swapping from being a whole blood donor to being a plasma donor," says Blood Service chief executive Sam Cliffe. "It takes a little longer but you can do it more often."
It is helping to save more people like Brendan.
"Thank you very much," says Brendan. "You've just pretty much helped me through my journey of life."
Newshub.
