Clinical features of polycythaemic patients with chronic obstructive non-specific lung disease.

Forty-five patients with chronic hypoxic lung disease were studied to ascertain whether those with polycythaemia had specific distinguishing features. Thirty-three patients had red cell volumes less than 120% of the predicted normal values, and 12 patients had red cell volumes greater than this level and were regarded as polycythaemic. The latter were found to have a higher incidence of the features associated with obstructive bronchitis, whereas the nonpolycythaemic subjects had more emphysematous characteristics. These findings may facilitate the selection of those patients who may benefit from a therapeutic reduction of red cell volume.