A total of 107 recipients, who did not show any evidence of hepatic disorders in pretransfusional liver function tests and gave a negative reaction for
HBsAg, were observed from 3 weeks to 3 months after
blood transfusion of 711 units of blood. Of 107 recipients, 18 (17%) developed posttransfusional non-A, non-B
hepatitis (PTH). It was detected in 2 of 71 recipients (3%) with blood
guanase activities below 3.5 U/L and in 16 of 36 recipients (44%) with blood
guanase activities above 3.6 U/L. It is considered that development of PTH could be reduced by avoiding use of donor blood with high
guanase activity. We adopted an automated method for measuring
guanase in donor blood in the Tokushima Red Cross blood center and examined the incidence of PTH when donor blood with high
guanase activity was excluded. Of 112 recipients, 8 (7%) developed PTH. The incidence of PTH was 17% before adoption of the
guanase screening test and 7% after its adoption. This work shows that for prevention of PTH it is very important to screen donor blood for
guanase activity and discard blood with high
guanase activity.