From the Guidelines
Hemoglobin can increase while hematocrit decreases due to various physiological conditions, laboratory errors, or medical treatments, and it is crucial to investigate the underlying cause to ensure proper management and prevent potential complications. When analyzing the relationship between hemoglobin and hematocrit, it is essential to consider the potential effects of erythropoietin stimulating agents (ESAs) on these values, as seen in the study by Auerbach et al. 1. Some possible explanations for this discrepancy include:
- Dehydration, which can reduce plasma volume and cause hemoglobin concentration to appear elevated while hematocrit may be normal or decreased
- Certain medical conditions, such as spherocytosis or hemoglobinopathies, that can affect the shape or structure of red blood cells
- Laboratory errors, such as improper sample handling or calibration issues
- Recent blood transfusions or the use of ESAs, which can temporarily affect these values differently, as noted in the study by Steinmetz et al. 1 It is vital to further investigate this pattern in lab results, including repeat testing and evaluation for underlying conditions, to ensure proper management and prevent potential complications, such as those associated with the use of ESAs, including increased risk of venous thromboembolism (VTE) and mortality, as discussed in the study 1.
From the Research
Hemoglobin and Hematocrit Relationship
- Hemoglobin and hematocrit are two related but distinct measures of blood composition, with hemoglobin being a protein in red blood cells that carries oxygen, and hematocrit being the proportion of red blood cells in the blood 2.
- An increase in hemoglobin can occur due to various factors, including increased erythropoiesis (production of red blood cells) stimulated by erythropoietin, while a decrease in hematocrit can occur due to factors such as blood dilution or loss of red blood cells 3.
Possible Causes of Discrepancy
- One possible cause of a discrepancy between hemoglobin and hematocrit levels is the effect of intravenous fluid administration, which can dilute the blood and decrease hematocrit levels while leaving hemoglobin levels relatively unaffected 3.
- Another possible cause is the presence of renal insufficiency, which can affect the production of erythropoietin and the biosynthesis of hemoglobin, leading to changes in hemoglobin and hematocrit levels 2.
- Additionally, iron homeostasis and erythropoiesis are interconnected, and changes in iron levels can affect hemoglobin synthesis and erythropoiesis, potentially leading to discrepancies between hemoglobin and hematocrit levels 4.
Clinical Implications
- The discrepancy between hemoglobin and hematocrit levels can have significant clinical implications, particularly in patients with underlying medical conditions such as renal insufficiency or gastrointestinal bleeding 5.
- It is essential to consider the underlying causes of the discrepancy and to evaluate the patient's clinical condition and laboratory results as a whole, rather than relying solely on hemoglobin or hematocrit levels 6.