RBC INDICES,IRON METABOLISM, ANEMIAS &POLYCYTHEMIA

RBC INDICES,IRON METABOLISM, ANEMIAS &POLYCYTHEMIA

LECTURE FIRST YEAR MBBS

LECTURE 03 AND 04

BONE MARROW MICRO ENVIRONMENT

• Fat cells

• Fibroblast

• Reticulum cells

• Endothelial cells

• Macrophages

• Collagen

• Fibronectin

ANAEMIAReduction In Oxygen

Carrying

Capacity Of Blood

Or

Reduction In

Haemoglobin

Level Below Lower Limit

Of Normal For That Age

And Sex

Classification of AnaemiaAccording to Cause

• Blood Loss

• Increased Destruction of RBCs

• Impaired Production of RBCs

BLOOD LOSS

Acute : Trauma

Chronic : Lesions Of

G.I.Tract

Gynecological

Losses

Increased Rate Of Destruction

Of RBCs (HEMOLYTIC ANEMIAS)

Intra Corpuscular Defects

Hereditary:

Red Cell Membrane Disorders

Spherocytosis, Elliptocytosis

Red Cell Enzyme DeficienciesPyruvate kinase deficiency

Hexo kinase deficiency

G6PD deficiency

Increased Rate Of Destruction

Of RBCs (HEMOLYTIC ANEMIAS)

Disorders Of Hemoglobin Synthesis

Deficient Globin Synthesis:

Thalassemia Syndromes

Structurally Abnormal Globin Synthesis

Haemoglobinopathies:

Sickle Cell Anemia

Unstable Haemoglobins

Increased Rate Of Destruction

Of RBCs (HEMOLYTIC ANEMIAS)

Acquired

Membrane Defect:Paroxysmal Nocturnal Hemoglobinuria

INCREASED RATE OF DESTRUCTION

OF RBCs (HEMOLYTIC ANEMIAS)

• Extra Corpuscular Defects• Antibody mediated• Infections• Malaria

Impaired Red Cell Production

Disturbance Of Proliferation And

Differentiation Of Stem Cells:

Aplastic Anemia

Anemia Of Renal Failure

Disturbance Of Proliferation And Maturation

Of Erythroblasts

Defective DNA Synthesis :Deficiency Or Impaired Utilization Of Vit B12 And Folic Acid

(Megaloblastic Anemias)

Defective Hemoglobin Synthesis:

Deficient Heme Synthesis e.g. Iron Deficiency

Deficient Globin Synthesis e.g. Thalassemias

Disturbance Of Proliferation And Maturation Of

Erythroblasts

Unknown Or Multiple Mechanisms:

Sideroblastic Anemia

Anemia Of Chronic Infections

Myelophthisic Anemias Due To Marrow

Infiltration

ABSOLUTE VALUES

Red Cell Indices

MCV: Mean Corpuscular Volume

MCH: Mean Corpuscular Haemoglobin

MCHC: Mean Corpuscular Haemoglobin

Concentration

Based On Following Parameters

Red Cell Count

Haemoglobin Level

Packed Cell Volume

MCV= PCV

RED CELL COUNT = 90 fl

MCH= HB

RED CELL COUNT = 30 pg

MCHC= HB

PCV = 333 g/l

Morphological Classification(Based On RBC Morphology & Absolute Values)

Hypochromic Microytic

(MCV<76 fl, MCH< 27 pg)

• Iron Deficiency Anemia

• Thalassemia

• Anaemia Of Chronic Disorders

• Siderobastic Anemia

• Lead Poisoning

Morphological Classification(Based On RBC Morphology & Absolute Values)

Normochromic Normocytic

(MCV & MCH Within Normal Range)

• Acute Blood Loss

• Mixed Deficiences

• Haemolytic Anaemias

• Bone Marrow Failure e.g. Post Chemotherapy

• Bone Marrow Infiltration e.g. Carcinoma

• Renal Disease

Morphological Classification(Based On Rbc Morphology & Absolute Values)

Macrocytic

MCV > 96fl

• Megaloblastic Marrow

• Vitamin B12 Deficiency

• Folate Deficiency

IRON METABOLISM

Iron Metabolism

Body Iron Distribution

Total Iron 2-5g

Haemoglobin Contains 2/3 (1.7 -- 2.4g)

Storage Iron 1/3 (0.5 - 1.5g)

Myoglobin 200 - 300mg

Enzymes Traces

Iron Metabolism

Dietary Iron

10 - 15mg In Western Diet

5 To 10% Is Absorbed

Food

Meat, Liver

Vegetable, Fruits, Eggs,

Dairy Products

Iron Metabolism

Storage Iron

Ferritin Water Soluble

Haemosiderin Insoluble

Iron Absorption

DUODENUM

MUCOSAL CELL(APOFERRITIN)

TRANSFERRIN

STORES TISSUES

Dietary

iron

ABSORPTION OF IRON

TRANSPORT AND STORAGE

IRON ABSORPTION

• Iron is absorbed mainly from the small intestine.

• It is absorbed through the intestinal cells (enterocytes)by pinocytosis and transported into the blood.

• Bile is essential for the absorption of iron.

• Iron is present mostly in ferric (Fe3+) form. It isconverted into ferrous form (Fe2+) which is absorbed intothe blood.

• Hydrochloric acid from gastric juice makesthe ferrous iron soluble so that it could be convertedinto ferric iron by the enzyme ferric reductase fromenterocytes.

• From enterocytes, ferric iron is transported into blood by a protein called ferroportin.

• In the blood, ferric iron is converted into ferrous iron and transported

Iron Absorption

FactorsSite : Duodenum

Form : Haem > Non Haem

Factors:

Favouring Absorption Reducing Absorption

Ferrous Form Ferric Form

Acids – HCL,VITC. Alkali – Antacid

Iron Deficiency Iron Excess

Increased Decreased

Erythropoiesis Erythropoiesis

Pregnancy Desferrioxamine

Tea, Phytate

IRON TRANSPORT

• Immediately after absorption into blood, iron combines with a β-globulin called apotransferrin secreted by liverthrough bile resulting in the formation of transferrin.

• And iron is transported in blood in the form of transferrin.Iron combines loosely with globin and can be released easily at any region of the body.„

Iron Transport

Beta Globulin

Transferrin (Liver)

I Molecule Binds 02 Atoms Of Iron

1/3 Is Saturated

Receptor Mediated

STORAGE OF IRON

• Iron is stored in large quantities in reticuloendothelial cells and liver hepatocytes.

• In other cells also it is stored in small quantities.

• In the cytoplasm of the cell, iron isstored as ferritin in large amount. Small quantity of iron is also stored as hemosiderin

REGULATION OF TOTAL IRON IN THE BODY

• Absorption and excretion of iron are maintained almost equally under normal physiological conditions.

• When the iron storage is saturated in the body, it automatically reduces the further absorption of iron from the gastrointestinal tract by feedback mechanism.

REGULATION OF TOTAL IRON IN THE BODY

• Factors which reduce the absorption of iron:1. Stoppage of apotransferrin formation in the liver, so that the iron cannot be absorbed from the intestine.2. Reduction in the release of iron from the transferrin, so that transferrin is completely saturated with iron and further absorption is prevented

CAUSES OF IRON DEFICIENCY

Chronic Blood Loss:Uterine

GI Loss

Urinary

Rarely Other Sites

Increased Demands:Growing Age

Prematurity

Pregnancy

Lactation

Malabsorption:Gastrectomy

Coeliac Disease

Poor Diet:Under Developed Countries

Old Age

D/D OF HYPOCHROMIC MICROCYTIC

ANAEMIA

1. Iron Deficiency Anaemia

2. Anaemia Of Chronic Disorder

3. Thalasemia (Alpha Or Beta) Trait

4. Sideroblastic Anaemia

DIAGNOSIS OF IRON DEFICIENCY

Detailed History & Physical Examination

Blood Picture

Red Cell Indices

Biochemical Tests

Bone Marrow Iron

Hb Electrophoresis

LABORATORY FINDINGS

HAEMOGLOBIN:

RED CELL INDICES:

MCV MCH MCHC

RED CELL MORPHOLOGY:

Hypochromic Microcytic

BONE MARROW ASPIRATION:

Erythroid Hyperplasia

Iron Absent

LABORATORY FINDINGS

• RDW (Red Cell Distribution Width)

• Degree of variation in size of RBC

Low MCV Iron deficiency

High RDW

Low MCV β Thalassemia minor

Normal RDW

LABORATORY FINDINGS

SERUM FERRITIN: <15ug/l

SERUM IRON

TOTAL IRON BINDING CAPACITY

SATURATION OF TRANSFERRIN

Free erythrocyte protoporphyrin

Soluble transferrin receptor

INVESTIGATION OF CAUSE OF IRON

DEFICENCY

Careful History Taking

Stool For Occult Blood/ Ova Of Hook Worm

GI Endoscopy

MEGALOBLASTIC

ANAEMIA

Vitamin B12 (Cyanocobalamin)

• Vitamin B12, intrinsic factor and folic acid are necessary for the maturation of RBCs.

• Vitamin B12 is the maturation factor necessary for erythropoiesis.SourceVitamin B12 is called extrinsic factor since it is obtained mostly from diet. Its absorption from intestine requires the presence of intrinsic factor of Castle.

Vitamin B12

• Vitamin B12 is stored mostly in liver and in small quantity in muscle.

• When necessary, it is transported to the bone marrow to promote maturation of RBCs.

• It is also produced in thelarge intestine by the intestinal flora.

Vitamin B12

• Essential for synthesis of DNA in RBCs.

• Its defciency leads to failure in maturation of the cell and reduction in the cell division.

• Cells are larger with fragile and weak cell membrane resulting in macrocytic anemia.

• Defciency of vitamin B12 causes pernicious anemia. So, vitamin B12 is called antipernicious factor

Intrinsic Factor of Castle

• Intrinsic factor of castle is produced in gastric mucosa by the parietal cells of the gastric glands. It is essentialfor the absorption of vitamin B12 from intestine.

• In the absence of intrinsic factor, vitamin B12 is not absorbed from intestine.

Defciency of intrinsic factor

• This leads to pernicious anemia.

• DEFICIENCY occurs in:i. Severe gastritisii. Ulceriii. Gastrectomy.

VITAMIN B12 FOLATE NUTRITIONAL

ASPECTS

VIT B12 FOLATE

NORMAL DAILY

DIETARY INTAKE

7 – 30ug 200 – 250 ug

MAIN FOODS ANIMAL PRODUCE

ONLY

MOST FOODS, LIVER

GREENS & YEAST

COOKING LITTLE EFECT EASILY DESTROYED

MINIMAL ADULT

DAILY REQUIREMENT

1 – 2 ug 150 ug

BODY STORES 2 – 3 mg

(SUFFICIENT FOR 2

– 4 Yrs)

10 – 12 mg(SUFFICIENT

FOR 4 MONTHS)

ABSORPTIO SITE ILIEUM DUODENUM &

JEJUNUM

MECHANISM INTRINSIC FACTOR CONVERSION TO

MONO GLUTAMATE

FORM

LIMIT 2 – 3 ug DAILY 50 – 80 % OF DIETARY

CONTENT

ENTERO HEPATIC 5 – 10 ug DAILY 90 ug DAY

TRANSPORT IN

PLASMA

MOST BOUND TO TC,

I, TC II ESSENTIAL

FOR CELL UPTAKE

WEAKLY BOUND TO

ALBUMIN

MAJOR

INTRACELLULAR

FORMS

METHYL & DEOXY –

ADENOSYL

COBALAMIN

REDUCED

POLYGLUTAMATE

DERIVATIVES

USUAL THERAPEUTIC

FORM

HYDROXYCOBALAM

IN

FOLIC ACID

CLINICAL FEATURES

1. Insidious Onset/Asymptomatic Initially

2. Progressive Signs & Symptoms Of Anaemia

3. Mild Jaundice

4. Glossitis and Angular Stomatitis

5. Loose Motions/Nausea/Weight Loss

6. Purpura (Rarely)

7. Skin Pigmentation (Rarely)

8. CNS Symptoms

Peripheral Neuropathy. Tingling, Numbness,

Subacute Combined Degeneration Of Cord Due To Demyelination Of Dorsal And Dorsolateral Columns

9. Sterility

DEFINITE EFFECTS OF VIT B12 OR

FOLATE DEFICIENCY

Megaloblastic Anaemia

Macrocytosis Of Epithelial Cells

Neuropathy ( B12 Only)

Neural Tube Defects (Folate)

Sterility

LABORATORY FINDINGS

1. Blood Counts Pancytopenia

2. RBCs Morphology Macrocytosis

MCV > 96 Fl

Oval Macrocytosis,aniso Poikilocytosis

3. WBC Morphology Hypersegmented Neutrophils . (Six Or More Lobes)

4.

Bone Marrow Hypercellular Megaloblastic Erythropoesis.

Giant Metamyelocytes

5. Increased Unconjugated Bilirubin

6. Increased Serum LDH

DIAGNOSIS OF B12 OR FOLATE

DEFICIENCY

1. Estimation Of B12 And Folate Level

2. Therapeutic Trial.

1ug B12 100ug Folic Acid

Response - Increased Retics (in disease rectics

decrease)

Increased Haemoglobin

PERNICIOUS ANAEMIA

Autoimmune Origin

If Deficiency Due To Atrophic Gastritis

Affects Females More Often – Old Age, Familial

Association With Other Autoimmune Diseases

e.g Vitiligo, Myxedema, Thyrotoxicosis,

Increased Incidence Of Gastric Carcinoma.

Congenital Lack Of Intrinsic factor

DIAGNOSIS – ANTIBODIES IN SERUM

Pernicious anemia

• Pernicious anemia is the anemia due to deficiency of vitamin B12.

• It is also called Addison’s anemia. It is dueto atrophy of the gastric mucosa because of autoimmune destruction of parietal cells.

• The gastric atrophy results in decreased production of intrinsic factor and poorabsorption of vitamin B12, which is the maturation factor for RBC.

• RBCs are larger and immature with almostnormal or slightly low hemoglobin level. Synthesis of hemoglobin is almost normal in this type of anemia. So, cells are macrocytic and normochromic/hypochromic.

HAEMOLYTIC

ANAEMIA

CLASSIFICATION OF HAEMOLYTIC ANAEMIA

• HEREDITARY • MEMBRANE

– Hereditary spherocytosis– Hereditary elliptocytosis

• METABOLISM– G6PD deficiency– Pyruvate kinase deficiency

• HAEMOGLOBIN– Abnormal (Hb S, Hb C, Unstable Hb)– Deficient (Thalassemia)

CLASSIFICATION CONTINUED

• ACQUIRED

– IMMUNE

• AUTO IMMUNE

• ALLO IMMUNE

• Drug associated

• Sepsis

• DIC

CLINICAL FEATURES

Pallor – Anaemia

Jaundice – Fluctuating

Splenomegaly

Hepatomegaly

Gall Stones – Pigment

Color Of Urine – I/V Haemolysis

LABORATORY FINDINGS

DIVIDED INTO THREE GROUPS

1. FEATURES OF INCREASED RED CELLS

BREAKDOWN

a. serum bilirubin raised, unconjugated and bound to albumin

b. urine urobilinogen increased

c. Faecal Stercobilinogen Increased

LABORATORY INVESTIGATIONS

• Features Of Increased Red Cell Production

– Reticulocytosis

– Bone Marrow Erythroid Hyperplasia

LABORATORY FINDINGS

• Evidence Of Damaged Red Cells

– Morphology

– Osmotic Fragility

CAUSES OF INTRAVASCULAR

HAEMOLYSIS

1. Mismatched Blood Transfusion (Usually ABO)

2. G6PD Deficiency With Oxidant Stress

3. Some Autoimmune Haemolytic Anemias

4. Some Drug And Infection – Induced Haemolytic Anemias

CONSEQUENCES OF

INTRAVASCULAR HEMOLYSIS

Intravascular Haemolysis

Free Haemoglobin In Plasma

Bound To Haptoglobin

Removed By Liver (macrophages)

Decreased Haptoglobin

CONTINUED

Free Haemoglobin In Plasma

Filtered By Glomeruli

Reabsorbed By Renal Tubules

Renal Tubules Saturated

Free Haemoglobin In Urine

CONTINUED

Haemoglobin Breakdown In Tubular

Epithelium

Iron Converted To Haemosiderin

Shed With Cells In Urine

LABORATORY FEATURES

• Haemoglobinemia

• Haemoglobinuria

• Haemosidrinuria

• Methaemalbuminaemia

G6PD DEFICIENCY

DEFICIENCY OR FUNCTIONAL INADEQUACY LEADS

TO IMPAIRED REDUCTION OF GLUTATHIONE

OXIDANT STRESS

(DRUGS, INFECTIONS)

SEX LINKED MALES AFFECTTED

FEMALES ARE CARRIERS

G6PD DEFICIENCY

CLINICAL FEATURES

1. Acute Haemolytic Anaemia

2. Chronic Haemolytic Anaemia

3. Neonatal Jaundice

DIAGNOSIS:

Blood Film – Bite Cells

Reticulocyte, Heinz Bodies

Screening Tests

Enzyme Assays, On Red Cells

SICKLE CELL ANAEMIA

Hbs Crystalises At Low O2

Substitution Of Valine For Glutamic Acid In Position 6

Homozygous – Disease

Variable Clincal Expression

Severe Haemolytic Anaemia

Painful Vascular – Occlusive Crisis

Precipated By Infection , Acidosis

Deoxygenation ( Allitude, Operation – GA)

Heterozygous – Trait

No Anaemia , Normal RBC Morphology

Crisis May Be Caused By Anoxia/ Infection

HEREDITARY SPHEROCYTOSIS

Defect Or Deficiency Of Spectrin

(Memb Structural Protein) In RBC Membrane

Autosomal Dominant Usually

Anaemia

Jaundice - Pigment Gall Stones

Splenomegaly

Aplastic Crisis

HEREDITARY

SPHEROCYTOSIS• Pathogenesis

– Defective gene

– Abnormal or decreased spectrin

– RBC Membrane defect• Spherocytosis

• Increased osmotic fragility

• Increased glucose requirement

• Decreased deformity of RBCs

• Diagnosis– History and clinical examination

– Blood film examination

– Osmotic fragility test

Thalassaemia

Structure Of Haemoglobin

Sites Of Gobin Chain Synthesis

Types Of Haemoglobin In Adults

Hb A: Alpha2 Beta2 97%

Hb A2: Alpha2 Delta2 2-3%

Hb F: Alpha2 Gama2 < 1%

Disorders of Haemoglobin

Qualitative Haemoglobinopathies

Quantitative – Thalassaemias

Thalassaemias - Classification

On Genetic basis

• α –Thalassaemia

• β –Thalassaemia

–β 0 - Thalassaemia

–β+ Thalassaemia

Clinical Classification

Thal Minor –trait, asymptomatic

Thal Major –transfusion dependent

Thal Intermedia – transfusion not required

Hydrops Fetalis –death in utero,

α –Thalassaemia

Clinical Features

Anaemia

Hepato Splenomegaly

Skeletal Changes

Iron Overload

Growth Retardation

Lab Diagnosis

Blood CP

Hb Electrophoresis

Alpha/Beta Chain Analysis

DNA Analysis

Prenatal Diagnosis

Prevention

Blood Picture

1. Blood Counts

Haemoglobin Moderate to severe Anaemia

TLC Normal or Raised

Platelets Normal or Low

2. RBCs Morphology

Hypochoromic Microcytic

Anisopoikilocytosis

Nucleated RBCs

2. Reticulocyte Count Raised

Haemoglobin Electrophoresis

Thalassemia Trait

Increased Hemoglobin A2

Thalassemia Major

Increased Haemoglobin Hb F

APLASTIC ANAEMIA

PANCYTOPENIA

• Reduction in blood counts of all major cell lines.

- Red cells

- White cells

- Platelets

CAUSES PANCYTOPENIA- Decreased Marrow Function

- Aplasia

- Acute leukaemia, Myelodysplasia

- Infiltration with lymphoma, solid

tumours, tuberculosis

- Megaloblastic anaemia

- Paroxysmal nocturnal hemoglobinuria

- Myelofibrosis. (rare)

- Haemophagocytic syndrome

- Increased peripheral destruction

splenomegaly

APLASTIC ANAEMIA

• Aplastic (hypoplastic) anemia is defined as pancytopenia resulting from aplasia of bone marrow

CAUSES OF APLASTIC ANAEMIA

- Primary

- Congental Fanconi’s Anaemia

- Acquired Idiopathic

- Secondary

- Ionizing Radiations

- Chemicals

- Drugs

- Infections

PATHOGENESIS• Reduction in number of haemopoetic stem cells

in bone marrow.

- Defective stem cells

- Defective haemopoetic

microenvironment

- Deficiency of factors stimulating

haemopoetic

• Immunologicl Mechanisms

Causing inhibition of haemopoesis.

CLINICAL FEATURES

• Onset at any age – young adults usually

• Acute or insidious

• Signs and symptoms of anemia

• Fever – Neutropenia

• Bleeding – thrombocytopenia

• NO ORGANOMEGALY

LABORATORY FINDINGS

• Blood CP

- Haemoglobin – decreased

- TLC. Low – neutropenia

- Platelet count. low

• Reticulocyte Count

- Very low

LABORATORY FINDINGS

• Bone Marrow

- Hypoplasia. Loss of haemopoetic tissue and replacement by fat

• Bone marrow trephine

- Essential

- Hypoplastic

PURE RED CELL APLASIA

• Chronic Form

- Rare condition characterized by anemia with normal leucocytes and platelets and grossly reduced or absent erythroblasts in bone marrow

• Congenital Form

- Diamond Blackfan Syndrome

• Acute Form

- Parvo virus B19 infection

POLYCYTHEMIA

• Increase in circulating red blood cells above normal.

• May be associated with a real increase or only apparent because of decrease in plasma volume.

SECONDORY POLYCYTHEMIA

• Most common

• Also called physiological as in high altitude

• Due to Tissue hypoxia (cardiac and pulmonary diseases)

POLYCYTHEMIA VERA

• Polycythemia vera is caused by a genetic aberration in the hemocytoblastic cells that produce the blood cells.

• Negative feed back for regulation of RBC production is lost

EFFECT OF POLYCYTHEMIA ON CIRCULATORY SYSTEM

• Greatly increased viscosity of the blood

• decreases the rate of venous return to the heart

BUT

• blood volume is greatly increased in polycythemia,which tends to increase venous return

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