Plasma is the gold-coloured liquid in blood that carries blood cells around the body.
Made up of water, proteins and clotting factors, it is used in products for treating burn victims, people who have lost a lot of blood, kidney patients and chemotherapy patients.
New Zealand Blood Service communications manager Asuka Burge said the demand for plasma donations in Otago was increasing.
''We would love to see more of our generous and loyal blood donors ... consider making the switch to plasma donation.
''Healthcare services in Dunedin need on average 97 units of plasma per week, and there is no substitute for it.''
Plasma is collected through a machine, which separates the blood, stores plasma and returns red blood cells to the donor.
''Because the red blood cells are returned to the donor, it means donors can donate more frequently than whole blood donors,'' Ms Asuka said.
Anyone interested is urged to contact the Dunedin Donor Centre.
