Pathology Cheat Sheet
Classify Before You Chase
Anaemia classification for NEET-PG: MCV categories, reticulocyte count, iron studies, RDW, peripheral smear clues, and Perls Prussian blue marrow iron.
MedNext Academy | 3 min read
Classify Before You Chase
Anaemia classification for NEET-PG: MCV categories, reticulocyte count, iron studies, RDW, peripheral smear clues, and Perls Prussian blue marrow iron.
The definition and classification of anaemia by morphology and pathophysiology, and the investigations that narrow the diagnosis.
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- Anaemia is a reduction in haemoglobin concentration below the reference range for age and sex.
- The mean corpuscular volume divides anaemia into microcytic, normocytic, and macrocytic categories.
- Microcytic anaemias include iron deficiency, thalassaemia, anaemia of chronic disease, and sideroblastic anaemia.
- Macrocytic anaemias include megaloblastic causes such as B12 and folate deficiency and non-megaloblastic causes such as liver disease.
- Normocytic anaemias include acute blood loss, haemolysis, chronic disease, and marrow failure.
- The reticulocyte count separates underproduction anaemias with a low count from destruction or loss anaemias with a high count.
- Iron studies comprise serum iron, ferritin, total iron-binding capacity, and transferrin saturation.
- A raised red cell distribution width indicates anisocytosis and rises early in iron deficiency.
- Peripheral smear examination provides morphological clues such as target cells, spherocytes, and schistocytes.
- Bone marrow examination assesses cellularity, maturation, and iron stores when peripheral tests are inconclusive.
- Perls Prussian blue stain of the marrow is the gold standard for assessing iron stores.
- The pathophysiological classification groups anaemia into decreased production, increased destruction, and blood loss.
Mapped competency codes
- PA13.3
- PA13.4
- PA13.5
Continue into the full chapter
This summary maps to PA13-introduction-to-haematology.
Frequently Asked Questions
How is anaemia classified by red cell size?
By mean corpuscular volume into microcytic, normocytic, and macrocytic anaemias, which immediately narrows the differential diagnosis.
Why is the reticulocyte count central to anaemia workup?
It measures marrow erythroid response, separating underproduction anaemias with a low count from anaemias of red cell loss or destruction with a high count.
Which iron studies are used to evaluate anaemia?
Serum iron, ferritin, total iron-binding capacity, and transferrin saturation, which together characterise iron deficiency, chronic disease, and overload.
What is the gold standard for assessing body iron stores?
The Perls Prussian blue stain of a bone marrow aspirate, where absent stainable iron confirms iron deficiency.
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