Haematopoiesis & Approach to anaemia

Haematopoiesis&

Approach to Anaemia

Dr (Brig) YD SinghMBBS, MD, FIACM, DIT

Professor (Internal Medicine)

SKN Medical College & Gen Hospital

Pune 411 041

12 Apr 2023

Dr (Brig) YD Singh

Haematopoiesis (1)

• Process by which formed elements of blood – Produced & Regulated through series of steps

• Pluripotent haematopoietic stem cell– Capable of producing red cells,– All classes of granulocytes, monocytes, platelets– Mechanism to become committed to a given

lineage Not fully known

12 Apr 2023

Dr (Brig) YD Singh

Haematopoiesis (2)• Following lineage commitment

– Haematopoietic progenitor & precursor cells Come under regulatory influence of growth factors

and hormones.

– For red cell production Erythropoietin (EPO) is regulatory hormone

– EPO is required for Maintenance of Committed Erythroid progenitor cells

– In absence of EPO hormone Undergo programmed cell death (apoptosis)

12 Apr 2023 Dr (Brig) YD Singh

Factors Regulating RBCProduction

Regulated process of RBC production is Erythropoiesis

12 Apr 2023

Dr (Brig) YD Singh

RBC Characteristics• Mature red cell is 8 micron in diameter

– Anucleate , Biconcave & discoid in shape– Extremely pliable

Needs to traverse microcirculation easily

– Membrane integrity maintained by Intracellular generation of ATP

• Average RBC lives 100–120 day• 1% of all circulating RBC daily replaced• Erythron: Organ for red cell production

– Pool of marrow erythroid precursor cells & large mass of mature circulating RBCs

12 Apr 2023

Dr (Brig) YD Singh

RBCs : Normal Indices

• Mean cell volume (MCV)(Haematocrit x10) / (RBC count x 106) =90 ± 8 fL

• Mean Cell Haemoglobin (MCH)(Hb x 10) / (red cell count x 106) = 30 ± 3 pg

• Mean cell Hb concentration (MCHC)(Hb x 10) / hematocrit or MCH/MCV = 33 ± 2%

12 Apr 2023

Dr (Brig) YD Singh

Leukocytes• All Leukocytes derived from

– Common Stem cell in Bone marrow– 3/4th of nucleated cells of bone marrow

Committed to production of Leukocytes

• Mediate Inflammatory / Immune Responses– Include Neutrophils, T & B Lymphocytes – Natural Killer (NK) cells, Monocytes– Eosinophils & Basophils

• These cells have specific functions– Antibody production by B Lymphocytes– Destruction of bacteria by Neutrophils


Granulocytes Development (1)


Granulocytes Development (2)


Neutrophils

Neutrophil band with Döhle body

Normal Neutrophil


Eosinophil Large bright orange granules

usually bilobed Nucleus

Basophil Large purple-black granules fill the cell & obscure nucleus


Normal Bone Marrow

Low Power View

12 Apr 2023

Dr (Brig) YD Singh

Bone marrow

Normoblast Cell

Eosinophil Cell

Erythrocyte Cell

Myelocyte dividing

Myelocyte Cell

Normoblast with dividing Nucleus

Fat CellFat Cell

Fat Cell

Myelocyte Cell


Bone Marrow: Erythroid Hyperplasia


Bone Marrow: Myeloid Hyperplasia

12 Apr 2023

Dr (Brig) YD Singh

Anaemia: Introduction

• Serum Hb level or haematocrit < expected value for age & sex

• WHO criteria– Adult men

Blood Hb concentration <13 g/dL or Hematocrit <39%

– Adult women Blood Hb concentration <12 g/dL) or Hematocrit <37%

12 Apr 2023

Dr (Brig) YD Singh

Anaemia: Types

• Iron-Deficiency Anemia • Vitamin B12 Deficiency Anemia • Folate-Deficiency Anemia • Anemia of Chronic Disease• Haemolytic Anaemia • Aplastic Anemia • Myelodysplastic Syndromes

12 Apr 2023

Dr (Brig) YD Singh

Anaemia: Mechanisms

• 3 major physiologic mechanisms of anemia • Marrow production defects (Hypoproliferation)

– Reflects absolute or relative marrow failure – Erythroid marrow not proliferated appropriately– Can result from

Marrow damage Iron deficiency Inadequate erythropoietin stimulation

12 Apr 2023

Dr (Brig) YD Singh

Anaemia: Mechanisms

• Ineffective erythropoiesis (RBC maturation defects)– Nuclear maturation defects associated with

macrocytosis & abnormal marrow development – Cytoplasmic maturation defects associated with

microcytosis and hypochromia, usually from defects in hemoglobin synthesis

• Decreased erythrocyte survival: blood loss or hemolysis

12 Apr 2023

Dr (Brig) YD Singh

Anaemia: Symptoms & Signs (1)

• Often recognized by abnormal results on screening lab tests

• Signs and symptoms depend on– Level of anaemia – Time course over which it developed

Acute onset Anaemia Chronic Anaemia

12 Apr 2023

Dr (Brig) YD Singh


• Acute anaemia (nearly always due to blood loss or haemoptysis)

• If Loss of 10–15% of total blood volume– Hypotension – Decreased organ perfusion

• Loss of >30% of blood volume – Postural hypotension – Tachycardia

12 Apr 2023

Dr (Brig) YD Singh


• Loss of >40% of blood volume – Hypovolemic shock

Confusion Dyspnoea Diaphoresis Hypotension Tachycardia

• Haemolytic Anaemia – Presentation depends on mechanism that

leads to RBC destruction

12 Apr 2023

Dr (Brig) YD Singh


• Chronic or progressive anaemia – Presentation depends on age of patient – Adequacy of blood supply to critical organs

• Possible Symptom / Sign – Fatigue and Loss of stamina – Breathlessness (specially on exertion)– Pale skin and mucous membranes (Pallor) – Palpitation (Tachycardia, after physical exertion) – Forceful heartbeat (Heaving Apex beat)– High Volume pulse & Systolic flow murmur

12 Apr 2023

Dr (Brig) YD Singh


• In patients with coronary artery disease – Anginal episodes may appear or – Increase in frequency and severity

• In patients with carotid artery disease – Light-headedness – Dizziness may develop

12 Apr 2023

Dr (Brig) YD Singh

Anaemia: DD (1)

• Hypoproliferative anaemias (75% of cases) – Marrow damage

Infiltration/fibrosis Aplasia

– Iron deficiency (mild to moderate) – Decreased stimulation

Inflammation Metabolic defect (Hypothyroidism) Renal disease

12 Apr 2023

Dr (Brig) YD Singh

Anaemia: DD (2)• Maturation disorder

– Cytoplasmic defects Iron deficiency (severe) Thalassemia Sideroblastic

– Nuclear defects Folate deficiency , Vitamin B 12 deficiency Drug toxicity

– Methotrexate & Alkylating agents – Alcohol

Refractory anemia – Myelodysplasia

12 Apr 2023

Dr (Brig) YD Singh

Anaemia: DD (3)

• Haemolysis / Haemorrhage – Blood loss – Intravascular haemolysis – Metabolic defect – Membrane abnormality – Haemoglobinopathy – Autoimmune defect – Fragmentation haemolysis

12 Apr 2023

Dr (Brig) YD Singh

Anaemia: Diagnostic Approach (1)• 02 questions need to be answered:

– Type of Anaemia & Cause of Anaemia

• Careful history – Nutritional history

Related to diet, drugs or alcohol

– Family history of anaemia (Genetic)– Geographic backgrounds and ethnic origins

G 6 PD deficiency Haemoglobinopathies

– Middle Eastern, Mediterranean, or African origin

– Exposure to toxic agents or drugs

12 Apr 2023

Dr (Brig) YD Singh

Anaemia: Diagnostic Approach (2)

• Physical examination – May provide clues to mechanisms / cause of

anaemia Infection Blood in the stool Splenomegaly & Lymphadenopathy Petechiae suggest platelet dysfunction.

• Laboratory assessment – Including review of past laboratory

measurements to determine time of onset

12 Apr 2023

Dr (Brig) YD Singh


• Physiologic classification / Type of anaemia• Reticulocyte index <2.5 & Normocytic,

Normochromic anaemia – Hypoproliferative

Marrow damage: – Infiltration / fibrosis – Aplasia

Decreased stimulation:– Inflammation– Metabolic defect– Renal disease

12 Apr 2023

Dr (Brig) YD Singh


• Reticulocyte index <2.5 & microcytic or macrocytic anemia – Maturation disorder

Cytoplasmic defects: – Iron deficiency, – Thalassemia, Sideroblastic

Nuclear defects: – Folate deficiency– Vitamin B deficiency– Drug toxicity

12 Apr 2023

Dr (Brig) YD Singh


• Reticulocyte index ≥2.5 – Haemolysis / Haemorrhage

Blood loss Intravascular haemolysis Metabolic defect Membrane abnormality Haemoglobinopathy Autoimmune defect


Anaemia Algorithm

12 Apr 2023

Dr (Brig) YD Singh

Normal Blood Smear (Wright’s stain)

Normal RBCs, single Neutrophil & few platelets seen


Reticulocytes (Supravital Stain)

Reticulocyte count is key to initial classification of anemia Reticulocytes are RBCs recently released from marrow

12 Apr 2023

Dr (Brig) YD Singh

Severe Iron Def Anaemia(Wright’s stain)

Microcytic & Hypochromic RBCs smaller than nucleus of a Lymphocyte + marked variation in size (Anisocytosis) &

shape (Poikilocytosis)

12 Apr 2023

Dr (Brig) YD Singh

Macrocytosis

RBCs larger than small Lymphocyte & well haemoglobinized. Macrocytes are oval-shaped

(Macroovalocytes)

12 Apr 2023

Dr (Brig) YD Singh

Howell-Jolly bodies

In absence of functional spleen, nuclear remnants are not expelled from RBCs & remain as small homogeneously

staining blue inclusions on Wright stain

12 Apr 2023

Dr (Brig) YD Singh

Red cell changes in myelofibrosis

A Teardrop-shaped RBC & a Nucleated RBC is seen. These forms are seen in Myelofibrosis with Extramedullary

Haematopoiesis

12 Apr 2023

Dr (Brig) YD Singh

Red cell changes in Thalassemia & Liver disease

Target cells have a bull’s-eye appearance & are seen in Thalassemia & Liver disease

12 Apr 2023

Dr (Brig) YD Singh

Red cell changes in Sickle Cell Disease

Sickle shaped cells are seen in Sickle Cell disease

12 Apr 2023

Dr (Brig) YD Singh

Anaemia: Lab Tests• CBC

– Erythrocyte count Haemoglobin & Haematocrit Reticulocyte count Erythrocyte indices Mean cell volume (MCV) Mean cell haemoglobin Mean cell haemoglobin concentration

– Leukocyte count Cell differential Nuclear segmentation of Neutrophils

12 Apr 2023

Dr (Brig) YD Singh

Anaemia: Lab Tests

– Platelet count – Cell morphology

Cell size Anisocytosis (variations in cell size) Poikilocytosis (variations in cell shape) Polychromasia

– Iron supply studies Serum iron Total iron-binding capacity (TIBC) Serum ferritin, marrow iron stain

12 Apr 2023

Dr (Brig) YD Singh

Hypoproliferative Anaemia: Key Tests

• Serum iron & iron-binding capacity • Serum ferritin, to assess iron stores • Evaluation of renal & thyroid function • Marrow biopsy or aspirate

– Detect marrow damage or infiltrative disease

• Anemia of chronic inflammation shows– Low serum iron & Normal or low TIBC – Low percent transferrin saturation – Normal or high serum ferritin

12 Apr 2023

Dr (Brig) YD Singh

Hypoproliferative Anaemia: Key Tests• Mild to moderate iron deficiency anaemia:

– Low serum iron level & High TIBC – Low percent transferrin saturation – Low serum ferritin level

• Marrow damage by drug, infiltrative disease (Leukaemia / Lymphoma / Aplasia)– Peripheral blood and – Bone marrow morphology

• Infiltrative disease or fibrosis – Marrow biopsy will likely be required

12 Apr 2023

Dr (Brig) YD Singh

Maturation disorders Anemia: Tests

• Vitamin B12 • Folate • Serum iron and iron-binding capacity • Serum ferritin to assess iron stores • Haemoglobin electrophoresis

12 Apr 2023

Dr (Brig) YD Singh

Haemolytic Anemia: Tests

• Haemoglobin electrophoresis • Screen for red cell enzymes • Direct or indirect anti-globulin test • Cold agglutinin titre

12 Apr 2023

Dr (Brig) YD Singh

Anaemia Classification

• Based on defect in RBC production – Marrow production defects: Hypo-proliferation – Maturation defects: Ineffective Erythropoiesis – Decreased survival: Blood Loss / Haemolysis

• Classification by MCV – Microcytic: MCV <80 fL – Normocytic: MCV 80–100 fL – Macrocytic: MCV >100 fL

12 Apr 2023

Dr (Brig) YD Singh

Complications: Anaemia

• High-output Cardiac Failure • End-organ ischemia or infarct

– Myocardial infarction – Stroke

• Hypovolumic shock • Death

12 Apr 2023

Dr (Brig) YD Singh

Management Pearls: Anaemia

• Anaemia may be Multi-factorial – Finding one cause does not mean that no other

forms of anaemia are present – Iron deficiency may occur with folate / B12 def

Producing Dimorphic anaemia

• Iron deficiency often means – Occult blood loss– Worms infestation– Nutritional

12 Apr 2023

Dr (Brig) YD Singh

Treatment Approach: Anaemia

• Mild to Mod Anaemia– Initiate treatment when sp diagnosis is made

• Selection of treatment – Determined by cause of anaemia – Cause may be multi-factorial – Evaluate iron status before starting treatment

• Rarely anaemia may be so severe – RBC transfusions required before specific

diagnosis is made

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Haematopoiesis & Approach to anaemia