A sex difference in the leucocyte count.

In a study of a group of 325 blood donors between the ages of 18 and 65 years, the total leucocyte and polymorph counts of the females aged 50 to 65 years were found to be significantly lower than those of the corresponding group of male donors. In the whole series of female donors, there were significantly lower total leucocyte and lymphocyte counts with increasing age and a less significant (P [unk] 0.1) fall in the polymorph count. No age variation in the male counts was found. Analysis of large numbers of leucocyte counts performed on hospital patients has confirmed the sex difference in the total leucocyte count found in the blood donors. The factors responsible for the differences are discussed.