The clinical significance of beta-thromboglobulin and platelet factor-4 in polycythaemic patients.

Simultaneous assays of platelet factor 4 (PF-4) and beta-thromboglobulin (beta TG) were performed in 192 cases of myeloproliferative syndromes (polycythaemia vera and primary thrombocytosis, as defined by the Polycythaemia Vera Study Group). The results led to the following conclusions: (I) both assays must be combined in order to avoid a poor interpretation due to marker release in vitro; (II) the 'normality' of the values must take the platelet number into account, even in the 'normal' range of this parameter; (III) the sensitivity of the beta TG assay is greater than that of PF-4 when considering the correlation of the marker values with arterial accidents; (IV) the predictive value of an excessive level of beta TG and/or PF-4 is difficult to define, since only 13 of the cases studied had a vascular accident during the 12-month follow-up period, and the levels of the markers in these patients were not statistically different from the levels in those patients not experiencing such accidents.