Thrombocytosis, thrombocythaemia and iron deficiency in patients with polycythaemia vera.

6 patients with polycythaemia vera who also developed concomitant iron deficiency are reported. When oral iron therapy was given, there was a marked reduction in the previously elevated platelet counts in 4 patients; during 2-9 years of observation of these patients there was a significant inverse relationship between haemoglobin concentration and platelet count. In the other 2 patients the elevated platelet counts did not fall when iron therapy was given. The significance of these different patterns of response in relation to the causal mechanism of elevated platelet counts in patients with polycythaemia vera is discussed.