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Making the diagnosis in hematology
 

Making the diagnosis in hematology

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Making the diagnosis in hematology Making the diagnosis in hematology Presentation Transcript

  • Making the diagnosis in Hematology Part 1
  •  
  • Think of…
    • Too much
    • Too little
    • Poor function
  • RBC
    • Low Hb- Anemia
    • High Hb- Polycythaemia
  • Anemia
    • Microcytic anemia
    • Normocytic anemia
    • Macrocytic anemia
    • Aplastic anemia
    • Hemolytic anemia
  •  
  • Causes of microcytic anemia
    • S ideroblastic anemia
    • A nemia of chronic disease
    • T halassemia
    • I ron deficiency
  • Main lab features of iron deficiency anemia
    • Low serum iron.
    • Increased TIBC.
    • Increased Transferrin .
    • Low transferrin saturation.
    • Low Ferritin (confirms the diagnosis)
    • High Serum soluble transferrin receptors.
  • Main lab features of anemia of chronic disease
    • Low serum iron and TIBC
    • Ferritin normal/raised
    • Serum soluble transferrin receptor norma l.
  • Main features of sideroblastic anemia
    • Presence of ring sideroblast.
  •  
  • Thalassaemias
    • Genetic defect:
    • β- thalassaemia -point mutations
    • α- thalassaemia- gene deletions
    • ** Serum ferritin and iron stores are NORMAL
  • Types of Hemoglobin
  • β- thalassaemia
    • Homozygous:
    • No normal B chain produced (β0), or
    • Very reduced (β+).
    • Excess alpha chains.
    • Result: High Hb A2 ( α2δ2 ) and Hb F ( α2γ2 ) with small amounts of Hb A( α2β2 ).
    • Heterozygous
    • Symptomless microcytosis with or without mild anaemia
  • β- thalassaemia
  • β- thalassaemia
    • Thalassaemia minor (trait) -asymptomatic.
    • ( Raised HbA2 and HbF )
    • Thalassaemia intermedia - moderate anaemia.
    • Thalassaemia major (Cooley’s anemia) - severe anaemia (Homozygous β -thalassaemia)
  • α -thalassaemia
    • Gene deletion.
    • Deletion of one alpha chain (α+) or
    • Deletion of both alpha chain (α0) - most common.
    • **Normal people have Four alpha globin chains.
    • 2 from mum, 2 from dad.
  • α -thalassaemia
    • 1 gene deletion - Normal Hb . Normal blood picture.
    • 2 gene deletion (trait) – Hb H bodies seen or Hb A present . mild anemia.
    • 3gene deletion – Hb H disease .
    • ( Hb A2 normal or reduced .)
    • 4 gene deletion – Hb Barts . Hydrops fetalis (incompatible with life)
  • Causes of normocytic anemia
    • Anemia of chronic disease
    • Hypopituitarism
    • Hypothyroidism
    • Hypoadrenalism
    • Aplastic anemia
    • Some hemolytic anemia
    • Acute blood loss
  • Causes of macrocytic anemia
    • megaloblastic marrow
    • normoblastic marrow
  • Causes of macrocytosis (Raised MCV) with megaloblastic marrow
    • B12 deficiency
    • Pernicious anemia
    • Folate deficiency
    • Congenital enzyme deficiencies in DNA synthesis (e.g. orotic aciduria),
    • Drugs: hydroxyurea, azathioprine, zidovudine
    • Myelodysplasia due to dyserythropoiesis.
  • Causes of macrocytosis (Raised MCV) with normoblastic marrow
    • Physiological: Pregnancy.
    • Pathological causes:
    • alcohol excess
    • liver disease
    • Reticulocytosis
    • Hypothyroidism
    • aplastic anaemia
    • sideroblastic anaemia
    • pure red cell aplasia
    • Drugs (e.g. cytotoxics – azathioprine)
    • Spurious (agglutinated red cells measured on red cell counters)
    • Cold agglutinins due to autoagglutination of red cells.
  • Megaloblast vs normoblast.
    • Megaloblast:
    • Peripheral blood film shows oval macrocytes with hypersegmented polymorphs with six or more lobes in the nucleus.
    • Bone marrow shows megaloblastic erythropoeisis.
    • Normoblast:
    • Normal serum B12 and folate.
    • Normoblastic bone marrow .
    • ** Alcohol excess can be both.
  • Lab features in pernicious anemia
    • Raised serum bilirubin and LDH.
    • Raised Serum methylmalonic acid (MMA) AND homocysteine (HC) in B12 deficiency
    • ( only HC raised in folate deficiency ).
    • Low serum vitamin B12
  • Principles of Schilling’s test.
    • Oral Radioactive B12 is given.
    • Then i.m. injection of non-radioactive B12 to saturate B12 binding proteins and to flush out 58 Co-B12.
    • The urine is collected for 24 hours.
    • Normal person will excrete > 10% of the oral dose.
    • If <10 , repeat test with addition of oral IF.
    • If now normal , the diagnosis is pernicious anaemia or gastrectomy.
    • If still abnormal , the lesion must be in the terminal ileum or bacterial overgrowth.
  • Other causes of B12 deficiency
  • Causes of aplastic anemia
  • Lab findings in aplastic anemia
    • Pancytopenia
    • The virtual absence of reticulocytes
    • A hypocellular or aplastic bone marrow with increased fat spaces
  • Causes for pancytopenia
  • Causes of Hemolytic anemia
  • Lab findings suggestive of hemolysis.
    • Intravascular hemolysis:
    • Raised plasma Hb.
    • Raised hemosiderinuria.
    • Low haptaglobin
    • Presence of methaemalbumin (positive Schumm’s test)
  • Conditions with intravascular hemolysis
    • Mismatched blood transfusion
    • PNH
    • Septicemia
    • MAHA
    • March hemoglobinuria
    • G6PD deficiency.
  • Result of increased red cell breakdown
    • Anemia
    • Raised serum bilirubin
    • Raised LDH
    • Raised urobilinogen
    • Positive urinary hemosiderin
    • Reduced plasma haptaglobin.
  • Result of increased red cell production
    • Reticulocytosis/Polychromasia
    • Erythroid hyperplasia of bone marrow.
  • Causes of inherited hemolytic anemia
    • Hereditary spherocytosis
    • Thalassemias
    • Sickle syndromes
    • G6PD deficiency
    • Pyruvate kinase deficiency
  • Causes of acquired hemolytic anemia
    • Immune:
    • Autoimmune hemolytic anemia- warm and cold.
    • Drug induced immune hemolytic anemia.
    • Alloimmune hemolytic anemia
    • Non-immune:
    • Paroxysmal noctural hemoglobinuria (PNH).
    • Mechanical hemolytic anemia:
    • mechanical heart valves
    • MAHA
    • March hemoglobinuria.
  • How to find the cause of hemolysis?
    • Look at the blood film
    • Direct antiglobulin test.
    • +/- osmotic fragility test, Hb electrophoresis.
  • Specific features of each condition.
    • Hereditary spherocytosis.
    • Spherocytes on blood film
    • Positive osmotic fragility test.
    • Negative Coomb’s test.
    • Hereditary elliptocytosis.
    • Elliptical red cells.
    • Sickle cell disease.
    • Blood film show hyposplenism.
    • Positive sickle solubility test .
    • Hb electrophoresis (confirms diagnosis) shows Hb SS (80-95%) , No HbA, Hb F (2-20%).
    • G6PD deficiency
    • Blood count normal between attacks.
    • During attack, blood film show bite cells, blister cells, Heinz bodies and reticulocytosis.
    • Pyruvate kinase deficiency.
    • Blood film shows prickle cells and reticulocytosis.
    • Low pyruvate kinase activity.
  •  
    • Warm AIHA.
    • Spherocytosis.
    • IgG antibodies predominate.
    • Positive DAT ( IgG +/- complement )
    • Autoantibodies- specific for Rh blood grp system.
    • Autoimmune thrombocytopenia.
    • Cold AIHA
    • Red cells agglutinate in the cold temperature.
    • DAT is positive with complements (C3d) only .
    • Monoclonal IgM antibodies.
    • Drug induced hemolytic anemia.
    • Antibodies to drug only: quinidine, rifampicin.
    • Antibodies to the cell membrane only: methyldopa.
    • Antibodies to both : penicillin. hemolysis typically occurs over 7-10 days.
    • Diagnosis: Must have:
    • 1) Temporal association between administration of a drug and haemolytic anaemia, and recovery after withdrawal of the drug.
    • 2) Positive DAT.
    • 3) Drug dependent red cell antibodies detectable in the first and third mechanisms described above.
    • In the second mechanism, the antibodies are not drug-dependent and are indistinguishable from autoantibodies.
    • Paroxysmal nocturnal hemoglobinuria:
    • Mutation in the X-linked gene PIG-A
    • Evidence of intravascular haemolysis.
    • Flow cytometric analysis of red cells with anti-CD55 and anti-CD59 has replaced the Ham’s test.
    • Hypoplastic bone marrow
    • Major clinical signs:
    • Intravascular hemolysis, venous thrombosis, hemoglobinuria.
    • Characteristically only the urine voided at night and in the morning on waking is dark in colour.
    • Rx with eculizumab.
  • Causes of MAHA
    • When fragmentation of red cells occurs in an abnormal microcirculation.
    • Malignant hypertension
    • Eclampsia
    • HUS
    • TTP
    • Vasculitis
    • DIC
  • The Peripheral Blood film
    • Anisocytosis
    • is variation in RBC size, eg megaloblastic anaemia, thalassaemia, IDA.
    • Acanthocytes:
    • RBCs show many spicules due to an unstable red cell membrane lipid structure (eg in abetalipoproteinaemia).
    • Basophilic RBC stippling:
    • Denatured RNA found in RBCs, indicating accelerated erythropoiesis or defective Hb synthesis. Seen in lead poisoning, megaloblastic anaemia, myelodysplasia, liver disease, haemoglobinopathy eg thalassaemia.
    • Blasts:
    • Nucleated precursor cells. They are not normally in peripheral blood, but are seen in myelofibrosis, leukaemia or malignant infiltration by carcinoma.
    • Burr cells:
    • Irregularly shaped cells occurring in uraemia.
    • Dimorphic picture:
    • Two populations of red cells. Seen after treatment of Fe, B 12 or folate deficiency, post-transfusion, or with primary sideroblastic anaemia, where a clone of abnormal erythroblasts produce abnormal red cells, alongside normal red cell production.
    • Howell-Jolly bodies:
    • DNA nuclear remnants in RBCs, which are normally removed by the spleen. Seen post-splenectomy and in hyposplenism (eg sickle cell disease, coeliac disease, congenital, UC/Crohn's, myeloproliferative disease, amyloid). Also in dyserythopoietic states: myelodysplasia, megaloblastic anaemia.
    • Hypochromia:
    • Less dense staining of RBCs due to reduced Hb synthesis, seen in IDA, thalassaemia, and sideroblastic anaemia (iron stores unusable).
    • Left shift:
    • Immature neutrophils are sent out of the marrow, eg in infection.
    • Leucoerythroblastic anaemia:
    • Immature cells (myelocytes, promyelocytes, metamyelocytes, normoblasts) seen in film. Due to marrow infiltration (eg malignancy) when these cells are displaced; also seen in anorexia, sepsis, severe haemolysis.
    • Leukaemoid reaction:
    • A marked leucocytosis (WCC>50). Seen in severe illness eg with infection or burns, and also in leukaemia.
    • Pappenheimer bodies:
    • Granules of siderocytes containing iron. Seen in lead poisoning, carcinomatosis, and post-splenectomy.
    • Poikilocytosis:
    • is variation in RBC shape, eg in IDA, myelofibrosis, thalassaemia.
    • Polychromasia:
    • RBCs of different ages stain unevenly (young are bluer). This is a response to bleeding, haematinic replacement (ferrous sulfate, B 12 , folate), haemolysis, or marrow infiltration. Reticulocyte count is raised.
    • Reticulocytes:
    • (normal range: 0.8-2%). Young, larger RBCs (contain RNA) signifying active erythropoiesis. Increased in haemolysis, haemorrhage, and if B 12 , iron or folate is given to marrow that lack these.
    • Right shift:
    • Hypermature white cells: hypersegmented polymorphs (>5 lobes to nucleus) seen in megaloblastic anaemia, uraemia, and liver disease.
    • Rouleaux formation:
    • Red cells stack on each other (it causes a raised ESR). Seen with chronic inflammation, paraproteinaemia and myeloma.
    • Spherocytes:
    • Spherical cells found in hereditary spherocytosis and autoimmune haemolytic anaemia.
    • Schistocytes:
    • Fragmented RBCs sliced by fibrin bands, in intravascular haemolysis. Look for microangiopathic anaemia, eg DIC , haemolytic uraemic syndrome, thrombotic thrombocytopenic purpura or pre-eclampsia.
    • Target cells:
    • (also known as Mexican hat cells). These are RBCs with central staining, a ring of pallor, and an outer rim of staining seen in liver disease, hyposplenism, thalassaemia and, in small numbers, in iron-deficiency anaemia.
  • A normal blood film, with a neutrophil, normal red cells, and platelets (arrows).
  • Microcytic hypochromic cells in iron deficiency anaemia
  • Poikilocytosis and anisocytosis seen in iron deficiency anaemia.
  • Pathological ring sideroblasts in the bone marrow, with a perinuclear ring of iron granules, found in sideroblastic anaemia
  • Acanthocytosis.
  • Basophilic stippling.
  • Burr cells
  • Left-shift: presence of immature neutrophils in the blood
  • Pappenheimer bodies
  • Reticulocytes. RNA in RBCs; supravital staining (azure B; cresyl blue) is needed
  • Rouleaux formation
  • Film in hyposplenism: target cell (short arrow), acanthocyte (long arrow) and a Howell-Jolly body (arrow head).
  •  
  • A Cabot ring; these red/purple-staining filamentous figure-of-8 rings are often seen in RBCs with basophilic stippling. They occur in severe or megaloblastic anaemia, leukaemia, and lead poisoning.
  • Megaloblastic anaemia: peripheral blood film showing many macrocytes and one hypersegmented neutrophil (normally there should be <5 segments).
  • A bite cell in G6PD, following removal of Heinz bodies by the spleen. Heinz bodies are formed from oxidized, denatured Hb during oxidative crises
  • Blister cells (arrows) in G6PD, following removal of Heinz bodies. Also contracted red cells (arrowheads).
  •  
  • Microangiopathic anaemia eg from DIC: numerous cell fragments (schistocytes) are present
  • Fibrin strands, deposited in HUS & TTP, slice up passing red cells (microangiopathic anaemia).
  • Hereditary spherocytosis.
  •  
  • Hereditary elliptocytosis
  • Blood film in sickle-cell anaemia: there are sickle cells, target cells, and a nucleated red cell .
  •  
  •  
  •  
  •  
  •  
  • Leg ulcers in sickle cell disease.