A recent study demonstrates that red blood cell volume does not correlate well with low hemoglobin concentration in heart failure and cirrhosis patients, suggesting that changes in plasma volume are the main pathology for anemia in these patients. In fact, in 39% of patients, the main cause for anemia was an expanded PV.
Research has also demonstrated that among anemic CKD stage 3–5 patients, not on dialysis, only six patients had a decrease in red blood cell volume as the cause for their anemia, whereas 14 patients had an increase in plasma volume and therefore dilutional anemic.
In another study, eighteen CKD patients undergoing hemodialysis were anemic as determined by hemoglobin concentration. Of these patients, only nine (50%) were anemic related to low red blood cell volume whereas all patients displayed elevated plasma volume. This study hence confirms the shortcomings of basing anemia diagnosis on the assessment of hemoglobin concentration alone.
The diagnosis of anemia, based on low hemoglobin concentration may be seriously flawed by alterations in plasma volume. This has potential implications for patient treatment as it may be argued that patients with dilutional anemia should be treated for their elevated plasma volume while anemic patients should be treated for their low red blood cell volume. Nonetheless, patients diagnosed with anemia and dilutional anemia are today treated indifferently.