INTERFERENCE BY CRYOPROTEINS IN THE BLOOD WITH AUTOMATED CBCS

Cryoproteinemia may cause false elevation of automated white cell coun ts, platelet counts, or both, depending on, among other factors, the i nstrument or methodology used to count these cellular elements. Pseudo leukocytosis and pseudothrombocytosis were noted when cryoproteinemic specimens were processed through the Coulter STKS (Coulter Electronics , Hialeah, Fla), whereas only pseudothrombocytosis was evident when pr ocessed through the Technicon H1 (Tarrytown, NY). None of the red cell parameters of the automated CBCs performed on the STKS and H1 were ad versely affected. Although flagged at times for manual smear review, t he automated differential results on these specimens generated by the STKS and H1 were reliable. Timely recognition of the interfering effec ts of cryoproteins on the automated CBC, followed by appropriate recou rse (incubating the specimens at 37-degrees-C prior to reprocessing), is essential not only to obtain reliable test results, but also to aid in the detection of cryoproteinemia in previously unknown or suspecte d cases.