Definition and Classification of Anaemia

Vocabulary-style flashcards covering the definitions, classifications, physiological thresholds, and aetiological causes of anaemia based on the lecture transcript.

Anaemia (Functional)

The inability of RBCs to supply sufficient $O_2$ to body cells for normal tissue respiration, occurring when oxygen carrying capacity is insufficient for tissue demand.

Anaemia (Epidemiological)

The reduction in $Hb$ concentration or number of red blood cells below the reference value for an individual's age, sex, and place of abode.

Adult Male Anaemia Threshold

A hemoglobin level less than $13.0\,g/dL$.

Adult Female Anaemia Threshold

A hemoglobin level less than $12.0\,g/dL$, though lower values may occur in pregnancy due to increased plasma volume.

Newborn Anaemia Threshold

A hemoglobin level less than $13.5\,g/dL$ for infants from birth to approximately $3$ months.

Normocytic Normochromic Anaemia

Anaemia where RBCs are normal in size ($7.5-8.7\,\mu m$) and color, often caused by acute blood loss, chronic disease, or bone marrow failure.

Microcytic Hypochromic Anaemia

Anaemia characterized by RBCs reduced in size ($< 7.5\,\mu m$) and pale color, usually resulting from defective haem or globin synthesis.

Macrocytic Normochromic Anaemia

Anaemia where RBCs are increased in size ($> 8.7\,\mu m$) with normal color, typically resulting from impaired DNA synthesis.

Epistaxis

Bleeding originating from the nose, which can be caused by local inflammation, tumors, or malignant hypertension.

Haemoptysis

Bleeding from the chest or lungs, commonly caused by Tuberculosis (Tb) or chronic heart failure.

Haematemesis

The vomiting of blood, often caused by stomach cancers, chronic duodenal ulcers, or esophageal varices.

Haemochezia

The passage of frank, bright red blood in the stool originating from disorders in the anus and rectum.

Melaena

Dark, altered blood in the stool originating from the upper gastrointestinal tract.

Occult blood

Hidden micro-bleeding in the stool, often caused by hookworm infestation.

Haematuria

The presence of blood in the urine, with causes ranging from renal papillary necrosis to schistosomiasis or stones.

Menorrhagia

Excessive vaginal bleeding during menstruation, often linked to fibroids, cervical cancer, or endometriosis.

Petechiae

Small, pinpoint hemorrhages into the skin, often associated with thrombocytopaenia or DIC.

Haemarthrosis

Bleeding into the joints, which is a characteristic clinical feature of Haemophilia.

Haemolytic State

A condition where red blood cell survival lifespan is significantly shortened to less than $60$ days.

Intravascular Haemolysis

RBC destruction occurring entirely within the circulating vasculature, driven by complement lysis and characteristic of $IgM$ antibody interactions.

Extravascular Haemolysis

RBC lysis mediated by the mononuclear phagocytic system, primarily in the spleen, characteristic of $IgG$ antibodies.

Haptoglobin

A protein that binds and 'mops up' raw hemoglobin released directly into circulation during intravascular haemolysis.

Microspherocyte

A rigid, spherical RBC formed when splenic macrophages shave membrane off a cell; they lack central pallor and cannot navigate narrow sinusoids.

Zieve’s triad

A syndrome featuring alcoholic liver disease, hyperlipidaemia, and haemolytic anaemia.

Enzymopathy

Abnormalities of RBC enzymes in energy-producing pathways (e.g., Pyruvate kinase) or reducing power pathways (e.g., $G6PD$).

Thalassaemias

Quantitative haemoglobinopathies arising from disrupted or defective production volume of hemoglobin chains.

Warm Antibody Immune Anaemia

Anaemia driven by antibodies that reach optimal reactivity with red cell antigens at body temperature ($37^{\circ}C$).

Alloantibody

An antibody produced against foreign red cell antigens, which does not destroy the individual's native RBCs but can target transfused cells.

Black Water Fever

Acute intravascular haemolysis resulting from Plasmodium falciparum invading and destroying RBCs.

Neo-antigen

The modification of the RBC membrane by drugs or toxins so that the host immune system recognizes the erythrocyte as a new, foreign antigen.

Hypersplenism

Heightened phagocytic clearing activity of the spleen, resulting in cytopaenia and usually paired with splenomegaly.

March Haemoglobinuria

Mechanical fracturing of RBCs in the capillary beds of the soles caused by sustained physical impact against hard ground.

Schistocytes

Red blood cell fragments formed when RBCs collide with fibrin strands on endothelial surfaces in narrowed vessel lumens.

2,3-biphosphoglyceric acid (2,3-BPG)

A molecule generated in an alkaline RBC environment that reduces the oxygen affinity of hemoglobin to optimize tissue delivery.

Erythropoietin

A hormone produced by renal parenchymal cells in response to hypoxia that stimulates the bone marrow to produce more red cells.