Soluble plasma thrombomodulin levels in patients with chronic myeloproliferative disorder.

The plasma levels of soluble thrombomodulin (TM) were measured in 44 patients with chronic myeloproliferative disorder, 15 with polycythemia vera (PV), 29 with essential thrombocythemia (ET), and a group of 62 matched healthy controls. The younger patients had significantly lower TM levels (mean: 15.6 +/- 4.8 ng/mL) than the older patients (mean: 28.6 +/- 8.2 ng/mL, p < .001). Moreover, a significant negative correlation between platelet counts and plasma TM levels in healthy persons was noted (r = 0.317, p < .05). The only significant difference we found in plasma TM levels between patients and controls or among patients was between the young patients with ET (mean: 29.0 +/- 19.2 ng/mL) and young healthy controls (mean: 15.6 +/- 4.8 ng/mL). It is possible that younger ET patients with more active platelets are more susceptible to earlier vascular damage. The lack of any significant difference compared with the older patient population supports this hypothesis.