In patients with stage 3 to 5 chronic kidney disease (CKD), higher mean corpuscular volume (MCV) is associated with greater risks of death from cardiovascular problems, infection, and all other causes.
MCV is a measure of the average size of erythrocytes that is reported with complete blood counts. It’s typically used for differential diagnosis of anemia. In studies, MCV has been associated with mortality in patients with various diseases.
Yao-Peng Hsieh, MD, of Changhua Christian Hospital in Taiwan, and colleagues analyzed mortality by high- or low-mean MCV status (cutpoint 90.8 fl) for 1439 CKD outpatients treated at a single clinic during 2004-2011. Over 2 years of follow-up, 16.2% died. The overall mortality rate was significantly higher in the high MCV group compared with the low MCV group (22.7% vs 9.7%). After adjusting for demographic and clinical factors, including medication use, the researchers found that the high-mean MCV group had a 2.2, 3.6, and 2.2 times increased risk for all-cause mortality, cardiovascular mortality, and infection-related mortality, respectively, compared with the low-mean MCV group.
“Identifying high-risk patients for mortality by MCV could provide benefits for risk classification in patient care,” Dr Hsieh and colleagues concluded in the Clinical Journal of the American Society of Nephrology, published online ahead of print.
A previous study by Karthik K. Tennankore, MD, and colleagues identified a relationship between macrocytosis and mortality in chronic hemodialysis patients (BMC Nephrol 12:19,2011). The most common causes of macrocytosis are alcoholism, vitamin B12 or folate deficiency, hypothyroidism, and certain medications.
MCV may serve a biomarker. Among several possible mechanisms under consideration, investigators of the new study highlighted reduced antioxidant capacity in the body and impaired flow-mediated dilation.
The team acknowledged a lack of data on blood levels of thyroid function, folate, vitamin B12, iron, and reticulocytosis. Larger, prospective studies are warranted.