Effect of heamolysis on prostate-specific antigen.

Purpose. We have investigated the effect of haemolysis on free and total prostate-specific antigen (PSA) in daily clinical practice. Materials and Methods. Thirty-nine consecutive men were enrolled in this study. With an 18 gauge (G) needle 4 cc of blood samples were drawn from the right arm and 2 cc of it was expelled gently in a Vacutainer for regular PSA assay and the remaining was emptied into a second tube for complete haemolysis. Simultaneously 2 cc of more blood were taken with a 26 G insulin needle from the left arm of the same patient and expelled into another Vacutainer with forcing. All three samples were assayed for free PSA (fPSA), total PSA (tPSA), and potassium (K). Results. The results of the first tube were fPSA 0,535 ng/mL; tPSA 2,493 ng/mL; K(+) 4,178 mmol/L. The results from the haemolysis tube were 0,170 ng/mL; 0,929 ng/mL; 39,545 mmol/L for fPSA, tPSA, K(+), respectively, (P value was 0,001 for all the changes). In the same order the third tube results were 0,518 ng/mL, 2,322 ng/mL, and 7,11 mmol/L. Conclusions. Haemolysis may result in interference by decreasing free and total PSA falsely in daily blood draw practice, that could lead to misinterpreting the case in which especially small amount of increase may be of value.