ARE CURRENT METHODS OF MEASUREMENT OF ERYTHROPOIETIN (EPO) IN HUMAN PLASMA OR SERUM ADEQUATE FOR THE DIAGNOSIS OF POLYCYTHEMIA-VERA AND THEASSESSMENT OF EPO DEFICIENCY

Current methodology for the immunoassay of erythropoietin (EPO) in hum an plasma or serum is reviewed, with an emphasis on measurement of EPO concentrations in the low and normal ranges, analytical interference and blood sampling requirements. In only 2 out of 8 research or in-hou se immunoassays reported since 1987 was there evidence that patients w ith polycythaemia vera (PV) could be identified, PV being an EPO-indep endent form of polycythaemia in which EPO concentrations are low in un treated cases. The same was true for only 1 out of 13 currently availa ble kit methods. Remarkable differences in sample stability have been observed with different methods. Measurement of EPO in serum is recomm ended in most published articles. However, only EDTA plasma seems to b e acceptable for the one generally available method with proven high d iagnostic sensitivity for PV. It is concluded that most EPO assay meth ods have not been shown to be adequate for the measurement of the low EPO concentrations, and thus have poor diagnostic sensitivity for PV. It is inferred that they might not be appropriate to assess states of EPO deficiency. Only when a sufficiently sensitive diagnostic method b ecomes generally available will it be possible to define the various c auses of low EPO concentrations. As in other fields of polypeptide hor mone measurement, further developments in the field of EPO assay may b e expected to be important in diagnostic medicine.