Interesting data from the Copenhagen General Population Study on the effects of smoking on white and red blood cell count.
A Mendelian Randomization Approach in the Copenhagen General Population Study was conducted to assess whether tobacco smoking causally affects white and red blood cells and thrombocyte counts is unknown. Using this approach, the Copenhagen University Hospital, partner in the REPROGRAM project, tested the hypothesis that smoking causes increases in these blood cell indices. They included 104 607 white Danes aged 20 to 100 years from the cohort with information on blood cell indices and smoking habits. The group found interesting data on causality between smoking and increased blood leukocytes, neutrophils, lymphocytes, and monocytes, as well as increased hematocrit, hemoglobin, and mean corpuscular volume. The observational smoking relationships were long term for white blood cells and short term for red blood cell indices.
The full paper can be downloaded here: https://www.ncbi.nlm.nih.gov/pubmed/30866659