Low hematocrit causes
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Causes of Low Hematocrit: An Overview
Introduction to Low Hematocrit
Low hematocrit, a condition characterized by a reduced proportion of red blood cells (RBCs) in the blood, can lead to various health complications. Understanding the causes of low hematocrit is crucial for effective diagnosis and treatment.
Anemia and Prolonged Bleeding Time
One of the primary causes of low hematocrit is anemia, which can result in prolonged bleeding times. This is because RBCs play a critical role in promoting platelet interaction with blood vessel walls and activating platelets through the release of adenosine diphosphate (ADP) during hemostasis 1. Anemic patients often exhibit prolonged bleeding times, which can be corrected by RBC transfusions 1.
Hemodilution During Cardiopulmonary Bypass
Hemodilutional anemia is another significant cause of low hematocrit, particularly during cardiopulmonary bypass (CPB) in cardiac surgeries. Hemodilution can lead to inadequate oxygen delivery, resulting in ischemic organ injury and increased perioperative complications such as stroke, myocardial infarction, and renal failure 379. Studies have shown that maintaining a higher hematocrit level during CPB can improve patient outcomes and reduce the risk of adverse events 379.
Erythropoietin Deficiency in Renal Disease
Patients with end-stage renal disease often develop anemia due to erythropoietin deficiency. This condition is commonly treated with recombinant human erythropoietin (epoetin) to partially correct the anemia. However, maintaining a low hematocrit in these patients can lead to increased mortality and morbidity, particularly in those with concurrent cardiac disease 4.
Inaccurate Hematocrit Determinations
In some cases, low hematocrit readings may be due to errors in blood sample collection. For instance, using an inadequate volume of blood in anticoagulant tubes can result in falsely low hematocrit levels, as observed in a study involving children 6. This highlights the importance of proper blood sample handling to ensure accurate hematocrit measurements.
Hematocrit and Chronic Obstructive Pulmonary Disease (COPD)
In patients with severe COPD receiving long-term oxygen therapy (LTOT), low hematocrit is not uncommon and is associated with increased mortality and morbidity. The systemic inflammatory component of COPD can interfere with erythropoiesis, leading to anemia 8. Studies have shown that lower hematocrit levels in these patients correlate with poorer survival rates and higher hospitalization rates 8.
Conclusion
Low hematocrit can arise from various conditions, including anemia, hemodilution during CPB, erythropoietin deficiency in renal disease, and systemic inflammation in COPD. Accurate diagnosis and appropriate management of low hematocrit are essential to mitigate its adverse effects on patient health. Understanding the underlying causes and maintaining optimal hematocrit levels can significantly improve patient outcomes across different medical conditions.
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Most relevant research papers on this topic
The role of the hematocrit in bleeding.
Low hematocrit can prolong bleeding time in anemic patients, and transfusion of red blood cells may help correct this issue.
Cardiovascular events and intensity of treatment in polycythemia vera.
In patients with polycythemia vera, maintaining a hematocrit target of less than 45% significantly reduces the risk of cardiovascular death and major thrombosis compared to a target of 45 to 50%.
RCT
Large Human Trial
Highly CitedAdverse effects of low hematocrit during cardiopulmonary bypass in the adult: should current practice be changed?
Increasing lowest hematocrit during cardiopulmonary bypass is associated with worse perioperative organ dysfunction, increased resource use, and worse short- and intermediate-term mortality.
Observational StudyHighly CitedThe effects of normal as compared with low hematocrit values in patients with cardiac disease who are receiving hemodialysis and epoetin.
In patients with cardiac disease undergoing hemodialysis, epoetin to raise hematocrit to 42 percent is not recommended due to increased risks and decreased dialysis adequacy.
Non-RCTLarge Human TrialHighly CitedThe effect of hematocrit during hypothermic cardiopulmonary bypass in infant heart surgery: results from the combined Boston hematocrit trials.
A hematocrit level of 24% or higher during low-flow cardiopulmonary bypass in infant heart surgery is associated with higher Psychomotor Development Index scores and reduced lactate levels, but a universally "safe" hemodilution level cannot be determined.
RCTHighly CitedLowest hematocrit on bypass and adverse outcomes associated with coronary artery bypass grafting. Northern New England Cardiovascular Disease Study Group.
Low hematocrit during cardiopulmonary bypass is associated with increased risk of in-hospital mortality, and minimizing intraoperative anemia may improve outcomes for female and smaller patients.
Observational StudyHighly CitedPrognostic value of the hematocrit in patients with severe COPD receiving long-term oxygen therapy.
Low hematocrit is common in long-term oxygen therapy patients with COPD and is negatively associated with mortality and morbidity.
Observational StudyHighly CitedLow hematocrit during cardiopulmonary bypass is associated with increased risk of perioperative stroke in cardiac surgery.
Low hematocrit during cardiopulmonary bypass is an independent predictor of increased risk of perioperative stroke in cardiac surgery.
Observational StudyHighly CitedHematopoiesis and aging. V. A decline in hematocrit occurs in all aging female B6D2F1 mice.
A decline in hematocrit occurs in all aging female B6D2F1 mice, with an expansion of plasma volume contributing to the decrease.
Non-RCT
Animal Study