Smoking, drinking, and polycythaemia.

The mean packed cell volume is higher in the smoking population than in non-smokers.'' Chronic hypoxaemia, from whatever cause, tends to cause a rise in the packed cell volume.4 The obvious temptation is to invoke hypoxaemia, resulting from lung disease induced by smoking, to explain the high values found in smokers-but is this apparently straightforward explanation correct? The increase in packed cell volume in chronic hypoxaemia is due mainly to increased erythropoiesis and a rise in the red cell mass. When the red cell mass is above the normal range the condition is termed absolute polycythaemia.45 Evidence