However, it is now becoming clear that this approach may be somewhat simplistic. Once anemia is identified, the cause of impaired hemoglobin synthesis or erythrocytosis, or of increased red cell loss or destruction, is often sought and treatment (either of the underlying cause, or through the administration of packed donor red cells) initiated. 9 4įor these reasons, circulating hemoglobin concentrations are routinely measured in clinical practice. Given its diverse etiology, anemia is common, affecting over 1.6 billion people worldwide, 2 and is associated with impaired functional capacity, reduced quality of life, 3 and poorer outcome in diverse disease states. Such reductions can result from the destruction or loss of erythrocytes or a failure of their production, or from impaired hemoglobin synthesis. Measurement of total hemoglobin mass and plasma volume is now simple, cheap and safe, and its more routine use is advocated.Īnemia is defined as a reduction in the circulating concentration of hemoglobin () to < 120 g.l in non-pregnant females and < 130 g.l in males. The traditional inference that anemia generally reflects hemoglobin deficiency may be misleading, potentially resulting in inappropriate tests and therapeutic interventions to address ‘hemoglobin deficiency’ not ‘plasma volume excess’. Exemplar patients with identical (normal or raised) total hemoglobin masses were diagnosed as profoundly anemic (or not) depending on differences in plasma volume that had not been measured or even considered as a cause. Here, hemoglobin mass explained little of the variance in its concentration (adjusted R 2=0.109 and 0.052 P=0.11 and 0.16), whilst plasma volume did (R 2 change 0.724 and 0.805 in heart and liver disease respectively, P<0.0001). However, they were poorly related in liver disease (r=0.410, P=0.11) and heart failure patients (r=0.312, P=0.16). Hemoglobin mass correlated well with its concentration in the healthy, surgical and inflammatory bowel disease groups (r=0.687–0.871, P<0.001). But does this matter? We explored this issue in patients, measuring hemoglobin concentration, total hemoglobin mass (optimized carbon monoxide rebreathing method) and thereby calculating plasma volume in healthy volunteers, surgical patients, and those with inflammatory bowel disease, chronic liver disease or heart failure. Rarely is a rise in plasma volume relative to circulating total hemoglobin mass considered as a cause.

In practice, clinicians generally consider anemia (circulating hemoglobin concentration < 120 g.l −1 in non-pregnant females and < 130 g.l −1 in males) as due to impaired hemoglobin synthesis or increased erythrocyte loss or destruction.

Female hemoglobin and hematocrit levels