MedicalResearch.com Interview with: John M. Higgins, MD MGH Center for Systems Biology Boston, MA Medical Research: What is the background for this study? What are the main findings? Dr. Higgins: Hundreds of studies over the past 8 years have shown that increased variation in the size of red blood cells (RBCs) is associated with increased risk for a very wide range of common diseases, like heart disease, many types of cancer, infection, many autoimmune diseases, and lots of other conditions.  The size of red blood cells (RBCs) in the circulation of a healthy person usually varies by about 12-14%, meaning that if you took a sample of the cells, most of the bigger cells would be about 14% larger than the smaller cells.  People whose red blood cells show more variation in size have a greater risk of developing a wide range of diseases.  Also, among patients already diagnosed with many common diseases like heart disease or cancer, those with higher RBC size variation have worse outcomes.  It is unknown how all of these different diseases could be connected to variation in the size of red blood cells.  The study explains a major cause for this connection.  We find that the human body seems to slow down the production and destruction of RBCs in just about every major disease very slightly.  Since red blood cells gradually become smaller as they age, a delay in destruction will increase the fraction of small cells, and the overall variation in size increases.  The study also describes a method to estimate a patient’s RBC clearance rate. (more…)