Sex differences in blood cell counts in the Lothian Birth Cohort 1921 between 79 and 87 years

Haematological abnormalities are important to detect. In older adults there are few data that inform about normal ranges and the change in blood cell counts with ageing. These few data indicate that sex differences in blood cell counts persist beyond 70 years.

To determine normal ranges for blood cell counts and changes in counts and to examine the relationship between different blood cell counts for men and women.

The sample comprised Lothian Birth Cohort 1921 (LBC1921) participants seen at a mean of about 79 and 87 years of age. Full blood count was measured on each occasion. Also recorded were weight, smoking status, years of full-time education, and main occupation, serum B12, folate and creatinine.

We examined blood cell counts in 495 community-resident people with mean age 79.1 (range 77.8-80.6) and repeated this in 157 of them at mean age 86.7 (range 85.7-87.4) years. Normal ranges were similar for men and women for all blood cell types at both ages, but men had persistently significantly higher mean red cell and monocyte counts, and women significantly higher platelet counts. Between 79 and 87 years, red cell, lymphocyte and eosinophil counts fell significantly, neutrophil and platelet counts increased, and monocyte count was stable. Worsening renal function was associated with a decrease in mean red cell count.

Changes in blood cell counts in this cohort are consistent with persistent sex differences, age-related changes in renal function (red cells), background inflammation (neutrophils and platelets) and immunosenescence (lymphocytes).