22.13: 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 hand, iron deficiency anemia is caused by a lack of adequate iron intake or malabsorption, which impairs hemoglobin synthesis and, in turn, affects erythrocyte production.
Pernicious anemia occurs when the stomach mucosa atrophies, reducing vitamin B12 absorption and developing short-lived erythrocytes called macrocytes.
Hemolytic anemias occur when erythrocytes are destroyed faster than the bone marrow can replace them.
Sickle cell disease is a genetic disorder where abnormal hemoglobin causes RBCs to assume a sickle shape, leading to blockages in blood flow and pain. Thalassemia, another genetic condition, results in abnormal hemoglobin production, causing RBCs to be destroyed prematurely.
Polycythemia is the opposite of anemia, involving an overproduction of RBCs. This can increase blood viscosity, leading to clotting issues and complications such as stroke. Primary polycythemia, or polycythemia vera, is often due to genetic mutations, while secondary polycythemia results from conditions that increase erythropoietin production, like chronic hypoxia.
Hereditary spherocytosis causes RBCs to be sphere-shaped, leading to their early destruction in the spleen. G6PD deficiency, a metabolic disorder, makes RBCs more vulnerable to oxidative stress, causing hemolysis.
Diagnosis of erythrocyte disorders involves blood tests, including complete blood count (CBC) and specific tests for underlying causes. Treatment varies, focusing on addressing the root cause and managing symptoms.
