Anaemia (anemia) - classification (microcytic, normocytic and macrocytic) and pathophysiology

Summary

This informative video delves into anemia, a condition characterized by a reduced number of red blood cells or low hemoglobin levels. It explains the role of red blood cells in oxygen transport and the importance of hemoglobin. The video outlines the process of erythropoiesis, stimulated by hormones like erythropoietin, and how anemia is diagnosed through a full blood count, focusing on mean corpuscular volume (MCV) to categorize types of anemia. It also discusses causes of anemia, including decreased production, blood loss, and increased red blood cell destruction, and the significance of various blood tests in diagnosing hemolytic anemia. The video concludes with symptoms of anemia and encourages viewers to explore more on hematological disorders.

Takeaways

• 🩸 Anemia is defined by a low hemoglobin concentration, with thresholds of less than 120g/L in females and less than 140g/L in males.
• 🔴 Red blood cells (RBCs) are crucial for oxygen transport and maintaining the blood's pH, containing hemoglobin and various enzymes.
• 🧬 Erythropoiesis is the process of RBC production, stimulated by hormones like erythropoietin, which is produced in the kidneys.
• 🌡 Other hormones that aid in RBC production include thyroid hormones and androgens.
• 🚫 Microcytic anemia is characterized by small RBCs (<80 femtoliters) and can be caused by iron deficiency, chronic inflammatory disease, or thalassemia.
• 🔎 A normal MCV anemia with a low reticulocyte count might indicate a bone marrow disorder, while a high count could suggest hemolytic anemia or blood loss.
• 🌕 Macrocytic anemia is identified by large RBCs (>100 femtoliters) and can be caused by vitamin deficiencies, alcohol abuse, hypothyroidism, or pregnancy.
• 🔬 Hemolytic anemia can be diagnosed through elevated levels of lactate dehydrogenase, increased reticulocyte count, high bilirubin, and low haptoglobin levels.
• 🩺 Symptoms of anemia include fatigue, pallor, and icterus (jaundice), and can also present with bone tenderness, lymphadenopathy, and hepatosplenomegaly.
• 🔄 Anemia can be categorized based on RBC size (using MCV) or by the mechanism affecting the RBC lifecycle, such as decreased production, blood loss, or increased destruction.

Q & A

What is the medical definition of anemia?

Anemia is defined as a reduced absolute number of circulating red blood cells, a low hemoglobin concentration, or a low hematocrit.

What are the typical hemoglobin levels that indicate anemia in females and males?

Anemia in females is indicated by a hemoglobin level of less than 120 grams per liter, while in males it is less than 140 grams per liter.

What is the role of red blood cells in the human body?

Red blood cells are responsible for carrying oxygen around the body, containing hemoglobin molecules that bind oxygen, and they also carry carbon dioxide and help maintain the pH of the blood.

Where do red blood cells originate from and what is the process called?

Red blood cells originate from myeloid progenitor cells in the bone marrow. The process of erythrocyte production is called erythropoiesis.

What is erythropoietin and how does it relate to red blood cell production?

Erythropoietin is a hormone produced in the kidney that stimulates the production of red blood cells by sensing the adequacy of tissue oxygenation relative to an individual's metabolic activity.

What is the term for premature red blood cells and how do they mature?

The term for premature red blood cells is reticulocytes. They mature into red blood cells after entering the bloodstream and circulating for about 120 days.

How is an old or abnormal red blood cell removed from circulation?

Old or abnormal red blood cells are removed from circulation by the reticulo-endothelial system, which includes the spleen and liver where macrophages and monocytes clear them.

How can anemia be categorized using the mean corpuscular volume (MCV)?

Anemia can be categorized as microcytic (MCV less than 80 femtoliters), normocytic (MCV between 80 to 100 femtoliters), or macrocytic (MCV greater than 100 femtoliters) based on the size of the red blood cells.

What is the significance of a high or low reticulocyte count in anemia?

A high reticulocyte count can indicate hemolytic anemia or blood loss as the body tries to compensate by producing more red blood cells. A low reticulocyte count could signify a bone marrow disorder, such as aplastic anemia.

What are the potential causes of macrocytic anemia?

Potential causes of macrocytic anemia include vitamin B12 deficiency, folate deficiency, alcohol abuse, hypothyroidism, and pregnancy.

How can anemia be categorized based on the mechanism of red blood cell lifecycle?

Anemia can be categorized based on decreased production (e.g., bone marrow disorders, chronic kidney disease, hypothyroidism, vitamin B12 or iron deficiency, chronic inflammatory disease), blood loss, or increased red blood cell destruction (hemolysis).

What are the signs and symptoms of anemia?

Signs and symptoms of anemia include pallor, fatigue, low energy, scleral icterus, bony tenderness, lymphadenopathy, and hepatosplenomegaly.