Haematology Overview

Study Notes

Haematology is the study of blood and blood disorders.
This presentation covers learning objectives, blood cell disorders, haematological indices (including RBCs, MCV, MCHC, ESR, reticulocytes), anemia definitions, types, etiologies, investigations, treatment, and related topics like vitamin B12 deficiency anemia, folic acid deficiency and hemolytic anemia, polycythaemia, white blood cell disorders (leukemia, lymphoma), and hemostasis.

Knowledge section: relate pathophysiological basics and etiology of haematological disorders; describe epidemiology, manifestations, complications and management of haematological disorders.
Skills section: interpret clinical manifestations and investigations to formulate a reasonable diagnosis; apply evidence-based management plan for haematological disorders, distinguish patients in emergency situations, develop a comprehensive management plan to keep patients in normal homeostasis.

Covers various blood cell disorders, including red blood cell (RBC) disorders, white blood cell (WBC) disorders, and coagulation disorders.

RBC Shape: Normal RBCs are biconcave. Abnormal shapes include spherocytes, sickle cells, and target cells.
RBC Count: Normal ranges for men and women are given. Abnormally high or low counts indicate anemia or polycythemia.
RBC Diameter: Normal diameter is 7.2 microns. Abnormal sizes (microcytes, macrocytes, megalocytes, anisocytosis) are important in diagnosis.
Hematocrit (PCV): Percentage of packed RBCs in 100ml of blood. Normal values are given. Increased PCV suggests dehydration or polycythemia; decreased PCV suggests hypervolemia or anemia.
MCV: Mean corpuscular volume (volume of RBC). High or low values (macrocytic, microcytic) are diagnostic.
MCHC: Mean corpuscular hemoglobin concentration, often normal in normocytic anemia.High or low values are important in diagnosis.
ESR: Erythrocyte sedimentation rate (measure of inflammation). A high ESR can indicate inflammation, infection, or certain diseases.
Reticulocytes: Indicators of bone marrow activity. High reticulocyte count indicates bone marrow activity in response to blood loss or lysis. Low indicates decreased bone marrow production.

Definition: Reduced oxygen-carrying capacity of blood, typically defined by low hemoglobin (Hb) levels.
Etiology: Includes diminished intake, decreased absorption, increased loss and increased requirements.
Types: Microcytic hypochromic, normocytic normochromic, macrocytic normochromic.
Investigative approach: measuring RBC indices (MCV, MCHC) is critical
Treatment: Treating the underlying cause is crucial; blood transfusion is sometimes necessary.

Physiology: Shortened lifespan of RBCs due to various causes. Hemolysis occurs in the reticuloendothelial system (90%) or intravascularly (10%).
Etiology: Corpuscular defects (cell wall, enzymatic defects, hemoglobin defects) / Extracorpuscular causes (traumatic, immunological, infection or toxic factors).
Investigations: Lab work assessing the cause.

Definition: Elevated RBC count, high hemoglobin, or increased hematocrit.
Types: Primary (polycythemia vera) or secondary.
Investigations: Hematological tests such as complete blood count measure the cause.

Normal total leukocyte count given.
Granular and non-granular types of WBCs are presented.
Importance of immature WBCs/mature WBCs ratio (5-10%), and left-shift in infections.

Definition: Uncontrolled proliferation of leukocytes in the blood and bone marrow.
Classification: Acute and chronic (based on the maturity of the cancerous cells).
Etiology: Radiation, chemicals, genetic factors, and infections.

Definition: A balance between clotting and anti-clotting systems to maintain blood flow and prevent excessive bleeding.
Components of clotting system (vessels, platelets, and coagulation system).
Deficiencies: Can lead to bleeding or clotting disorders.