Related Experiment Video
Updated: Aug 1, 2026

05:23
Continuous Manual Exchange Transfusion for Patients with Sickle Cell Disease: An Efficient Method to Avoid Iron Overload
Published on: March 14, 2017
Viscosity and iron deficiency in treated polycythaemia
British Journal of Haematology
|September 1, 1981
Summary
In polycythaemia, whole-blood viscosity increases with lower mean corpuscular hemoglobin (MCH) when hemoglobin is standardized, driven by higher packed cell volume (PCV). Venesection controlled by PCV effectively corrects hyperviscosity in non-hypoxic cases.
Area of Science:
- Hematology
- Blood Rheology
Background:
- Iron deficiency can alter red blood cell characteristics.
- Polycythaemia is a condition characterized by an elevated packed cell volume (PCV).
- Whole-blood viscosity is a critical factor in cardiovascular health.
Purpose of the Study:
- To investigate the impact of red blood cell changes from iron deficiency on whole-blood viscosity in polycythaemia.
- To determine the relationship between mean corpuscular hemoglobin (MCH) and blood viscosity under different standardization conditions.
Main Methods:
- In vitro analysis of blood samples from polycythaemia patients treated with venesection.
- Adjusting packed cell volume (PCV) to a standard of 0.45.
- Adjusting hemoglobin (Hb) concentration to a standard of 14 g/dl.
- Measuring whole-blood viscosity and mean corpuscular hemoglobin (MCH).
Main Results:
- When PCV was standardized to 0.45, whole-blood viscosity did not correlate with decreasing MCH.
- When Hb concentration was standardized to 14 g/dl, whole-blood viscosity increased exponentially as MCH decreased.
- This viscosity increase was attributed to a rising PCV associated with falling MCH at the standard Hb level.
Conclusions:
- Venesection, monitored by PCV, can effectively manage hyperviscosity in polycythaemia unrelated to hypoxia.
- The interplay between MCH, PCV, and Hb concentration significantly influences blood viscosity.
- Further considerations are necessary for managing hyperviscosity in hypoxic polycythaemia.
Related Concept Videos
Blood Transfusion and Agglutination
Blood transfusion is a therapeutic measure to restore the blood volume after extensive blood loss due to an accident or a medical procedure. Blood transfusion involves drawing a certain amount of blood from a suitable donor and infusing it into the recipient.
History
The history of blood transfusion dates back to the 17th century, when early attempts were made in animals. In 1818 James Blundell, a British doctor, performed the first successful human blood transfusion. Later in 1900, Karl...
History
The history of blood transfusion dates back to the 17th century, when early attempts were made in animals. In 1818 James Blundell, a British doctor, performed the first successful human blood transfusion. Later in 1900, Karl...
Lifecycle of Erythrocytes
Erythrocytes, also known as red blood cells, constantly move through blood capillaries. As a result, they damage their plasma membrane due to the continuous friction. Typically, after 100 to 120 days, erythrocytes become rigid and fragile as they wear out. As they pass through small vessels in the spleen and liver, they can get trapped and break apart into fragments.
The resident phagocytic macrophages deal with these damaged cells by engulfing them and separating their globin and heme groups.
The resident phagocytic macrophages deal with these damaged cells by engulfing them and separating their globin and heme groups.
Disorders of Erythrocytes
Disorders of erythrocytes, or red blood cells (RBCs), include a range of conditions affecting their number, shape, or function.
Erythrocyte disorders can be broadly categorized into two main types: anemic and polycythemic conditions.
A low oxygen-carrying capacity of the blood due to the loss, lower production, or destruction of erythrocytes is termed anemia. Hemorrhagic anemia, for example, occurs when bleeding from an external wound or internal ulcer reduces erythrocyte counts.
On the other...
Erythrocyte disorders can be broadly categorized into two main types: anemic and polycythemic conditions.
A low oxygen-carrying capacity of the blood due to the loss, lower production, or destruction of erythrocytes is termed anemia. Hemorrhagic anemia, for example, occurs when bleeding from an external wound or internal ulcer reduces erythrocyte counts.
On the other...
Disorders of Hemostasis
Hemostasis, the process that stops bleeding after a blood vessel injury, is crucial for maintaining the integrity of the circulatory system. However, disorders of hemostasis can disrupt this delicate balance, leading to either excessive clotting or bleeding. These disorders can be broadly classified into thromboembolic disorders and bleeding disorders.
Thromboembolic Disorders
Two factors primarily cause thromboembolic conditions.
Thromboembolic Disorders
Two factors primarily cause thromboembolic conditions.
Vascular Resistance
Vascular resistance is a critical concept in understanding blood flow dynamics in the circulatory system. It refers to the resistance that blood encounters as it flows through the blood vessels. This resistance is a key factor in determining blood pressure and cardiac workload.
The primary determinants of vascular resistance are vessel diameter, blood viscosity, and vessel length. Among these, vessel diameter plays the most significant role due to the fourth power relationship described by...
The primary determinants of vascular resistance are vessel diameter, blood viscosity, and vessel length. Among these, vessel diameter plays the most significant role due to the fourth power relationship described by...
Factors Affecting Erythropoiesis
The cardiovascular system regulates the number of erythrocytes in the bloodstream to ensure optimal oxygen transport. It also prevents over-proliferation of these cells, which helps to maintain blood viscosity and flow rate.
Several factors influence the erythrocyte production rate, with tissue oxygen level being among the most critical. Intense exercise or high altitudes can cause tissue hypoxia, which triggers the kidneys to release more erythropoietin (EPO) into the bloodstream.
EPO then...
Several factors influence the erythrocyte production rate, with tissue oxygen level being among the most critical. Intense exercise or high altitudes can cause tissue hypoxia, which triggers the kidneys to release more erythropoietin (EPO) into the bloodstream.
EPO then...

