Hi Mark

I read from archives that PCR-RNA test is a form of NAT testing...I also read that blood donation is screened via NAT...Normally, the experts recommend not to use PCR RNA for diagnostic purpose because of cost and high false positive rate.....I also read some data that blood screening via NAT has very low false positive rate..Why the difference in false positive rate between NAT via blood screening vs PCR RNA?

NAT testing is US FDA approved for blood testing at blood centers for donated blood. It is not approved for routine diagnostic testing of individual patients. There are a variety of reasons for differences in perceived test performance. Because of the high cost, NAT testing at blood donation centers is used with pooled samples. In other words, 15-20 donor blood samples are mixed together and tested in a batch form. If the donor pool is positive, then all donor samples are tested with conventional HIV testing methods.