Anaemia Flashcards
(46 cards)
1
Q
What does low vs high reticulocytes mean?
A
LOW RETICULOCYTES = MARROW PROBLEM = DECREASED PRODUCTION
- Iron, folate, b12
- BM disorder: pure red cell aplasia, MDS, infiltration
- Anaemia of chronic disease
- Kidney disease
INCREASED RETICULOCYTES = MARROW RESPONDING NORMALLY = INCREASED RETICULOCYTES
- Haemolysis
- Thalassemia
- Blood loss
2
Q
Causes of microcytic, normocytic, macrocytic anaemia
A
MICROCYTIC (MCV <80) TAILS - thalassemia - anaplastic anaemia - iron deficiency anaemia - lead poisoning - sideroblastic anaemia
NORMOCYTIC (MCV 80-100) - Decreased Production: BM failure Chronic disease - Increased Red Cell Loss: Haemolysis Bleeding (acute)
MACROCYTIC (>100)
MEGALOBLASTIC
- B12 deficiency
- Folate deficiency
NON-MEGALOBLASTIC
- Myelodysplasia
- Liver disease
- Alcohol
- Pregnancy
- Hypothyroidism
3
Q
Features of the iron cycle
A
- Duodenal enterocytes (absorption)
- Erythroid precursors (utilisation)
- Reticuloendothelial macrophages (iron storage and recycling)
- Hepatocytes (iron storage and endocrine regulation)
4
Q
Ferroportin vs Transferrin
A
- Iron is either stored in enterocytes as ferritin
- FERROPORTIN is located on the BASOLATERAL side of the cell, where iron is transferred to the plasma by ferroportin and reaches its target cells bound to TRANSFERRIN
- TRANSFERRIN CARRIES IRON IN THE PLASMA
5
Q
Features of hepcidin
A
- HEPCIDICIN REGULATES FERROPORTIN
- HEPCIDIN BINDS TO FERROPORTIN AND INDUCES ITS DEGRADATION
- SYSTEMIC REGULATION OF IRON ABSORPTION
- Regulated by hypoxia, EPO, HFE, TFR2, HJV, inflammation
- Acute phase reactant largely mediated by IL-6
- Hepcidin correlates with ferritin
IRON DEFICIENCY = HEPCIDIN DECREASE = INCREASED ABSORPTION OF IRON
IRON OVERLOAD = HEPCIDIN INCREASE = DECREASE ABSORPTION OF IRON
NOTE:
- HIF-1a is important for EPO transcription
- It lowers hepcidin and ferritin levels to increase absorption of iron
In haemochromatosis there is decreased levels of hepcidin and thus increased absorption of iron
6
Q
Investigation findings of iron deficiency anaemia
A
Blood Film: microcytic hypochromic red cells, pencil cells, anisopoikilocytosis (RBC of different size/shapes).
Iron Studies: Low iron Low ferritin Low transferrin saturation High transferrin TIBC (total iron binding capacity) increased
7
Q
Iron studies of anaemia of chronic disease
A
Iron: low - normal
Transferrin: low - normal
Transferrin sat: low- normal
Ferritin: normal to high
Transferrin is DECREASED in inflammation, infection, malignancy, cirrhosis
8
Q
Structure of normal Hb
A
(A) Haemoglobin A - 95-98% of adult Hb (2 alpha chains and 2 beta protein chains)
- Alpha chain: chromosome 16
- Beta chain: chromosome 11
Mutations in globin genes results in decrease in globin chain production = thalassaemia
9
Q
What is thalassaemia?
A
Autosomal Recessive
- Thalassaemia is the disruption of normal ratio of alpha globin to beta globin chains = REDUCED GLOBIN CHAIN SYNTHESIS
- Unpaired chains precipitate causing destruction to erythroid precursors in bone marrow (ineffective erythopoeisis) and shortened survival in circulation
- Inadequate Hb production
- Distorted a:B ratios
- Ineffective erythropoiesis and haemolysis
Quantitative disorder - Beta thalassemia - Alpha thalassemia Qualitative diorder HbS: sickle cell disease
10
Q
Alpha Thalassaemia Syndromes
A
- 2 alpha genes on each chromosome 16 = 4 genes in total
(a) Silent Carrier: aa/a- = normal Hb, normal MCV
(b) Minor: aa/– or a-/a-: mild microcytic anaemia
Alpha thalassemia trait = A loss of two of the four alpha-globin alleles
(c) HbH disease: a-/– = moderate microcytic anaemia
Splenomegaly + iron overload
Elevated HbH inclusion bodies
(d) Hydrops fetalis, severe in utero anaemia: –/–
HbA2 NORMAL
Note: B thalassemia - HbA2 ELEVATED
11
Q
Beta thalassaemia Syndromes
A
- Beta globin gene mutations lead to impaired production of beta globin chains
- Classified according to degree of reduction
B+ = some protein produced
B0 = no protein produced - Severity of thalassaemia syndrome depends on nature of beta globin gene mutation
HbA2 (2 alpha, 2 delta) ELEVATED
Elevated HbF
TARGET CELLS
(a) MAJOR (transfusion dependent) = B0/B0 or B0/B+ =
Severe microcytic anaemia
(b) INTERMEDIATE (non-transfusion dependent) = B+/B+ = Moderate microcytic anaemia
(c) MINOR (trait/carrier) = B/B0, B/B+ = mild microcytic anaemia
12
Q
Investigations and Management of thalassemia
A
INVESTIGATIONS
- Peripheral blood smear: HbH inclusion bodies, target cells, teardrop cells, anisopoikilocytosis
- Confirmatory: Hb electrophoresis
Hbh disease alpha thalassemia: low MCV, normal HbA2, normal HbF, HbH present
beta thalassemia: low MCV, high HbA2, high HbF, absent HbH
- Transfusion therapy in thalassaemia major and some thalassaemia intermedia (stressful periods) to minimise complications of anaemia and suppress extra-medullary haematopoiesis
- Management excess iron and complications (cardiopulmonary, liver, endocrine, bone health)
- Folic acid
- LUSPATERCEPT - IMPROVES RBC MATURATION
13
Q
Structural variants of haemoglobin
A
Haemoglobin S/C/E are the most common
Hb S = sickle cell disease
14
Q
Features and management of haemoglobin S disease
A
Haemoglobin S (sickle cell disease)
- An abnormal haemoglobin from POINT MUTATION IN THE BETA GENE = substitution of a VALINE FOR GLUTAMIC ACID IN 6TH AMINO ACID OF BETA GLOBIN GENE)
- Resulting Hb TETRAMER (alpha2/betaS2) becomes poorly soluble when deoxygenated
- Potential life threatening complications from VASO-OCCLUSION in multiple organs - can cause INFARCTION in spleen/marrow/brain/kidney
HbS ELEVATED
BLOOD FILM
- Sickle cells
- Howell jolly bodies
- Target cells
- Achanthocytes
MANAGEMENT
- Avoid triggers and complications, eg: pain, infection
- Hydroxyurea - increases HbF percentage, protective against sickling
- Sickle Crisis: hydration, analgesia, O2, thrombo-prophylaxis, red cell exchange
- Immunisations
15
Q
Drug induced macrocytic anaemia (megaloblastic)
A
Anti-Folate Drugs: methotrexate, trimethoprim
DNA Synthesis: azathioprine, hydroxyurea, gemcitabine
Reduced Absorption: metformin, PPI, alcohol, phenytoin, isoniazid
NOTE: alcohol only affects folate, NOT B12
16
Q
Causes of macrocytic anaemia
A
Megaloblastic: folate deficiency, B12 deficiency
Non-Megaloblastic: hypothyroidism, alcohol, myelodysplasia, liver disease, pregnancy
17
Q
Relationship between homocysteine and folate/b12
A
Folic acid (folate) is one of the ‘B’ vitamins that is needed to metabolise homocysteine. Vitamin B12, another B vitamin, helps keep folate in its active form, allowing it to keep homocysteine levels low. Therefore, people who are deficient in these vitamins may have increased levels of homocysteine
High homocysteine = vitamin b12 /folate deficiency
18
Q
Absorption of B12
A
- Gastric parietal cells produce intrinsic factor
- IF-B12 complex is absorbed in the terminal ileum
19
Q
Causes of B12 deficiency
A
(A) Pernicious Anaemia
- Autoimmune destruction of gastric mucosa/parietal cells leading to reduced production of IF
- Therefore B12 cannot be absorbed in terminal ileum
- IF Ab (very specific but only 50% sensitive)
- Parietal cell Ab: sensitive but not specific
(B) Ileal Pathology
- Crohn’s disease
- Ileal resection
- Mutation/deficiency of receptor for IF
(C) Gastrectomy
(D) Nutrition
(E) Nitrous oxide poisoning - neuropathy
20
Q
Clinical features of B12 deficiency
A
- Glossitis, angular stomatitis, increased melanin
- Neural tube defects
- Subacute combined degeneration of the cord: reduced proprioception, weakness, sensory changes, Romberg sign, Lhermitte sign
Subacute combined degeneration of the cord: loss of propriopception, loss of reflexes, mild-moderate weakness, increased tone, extensor plantars, ataxia
21
Q
Blood film findings for b12 deficiency
A
Blood Film
- Macrocytic anaemia
- Hypersegmented neutrophils
- Low reticulocyte count
22
Q
Folate deficiency
- Site of absorption
- Causes
A
- ABSORPTION: SMALL INTESTINE - jejunum
Causes:
- Reduced dietary intake
- Increased requirements: haemolysis, pregnancy, chronic inflammation
- Malabsorption: small bowel pathology, drugs (phenytoin, isoniazid, alcohol)
- Impaired utilisation - methotrexate
23
Q
Causes of normocytic anaemia
A
Reduced Production
- Bone marrow failure
- Chronic disease
Increased Red Cell Loss
- Haemolysis
- Bleeding (acute)
24
Q
What is haemolysis and laboratory findings
A
- Shortened survival of circulating red blood cells (<100-120 days)
- Elevated reticulocytes
- Elevated LDH
- Elevated unconjugated bilirubin
- Decreased haptoglobin (glycoprotein from liver, binds free Hb)
- Elevated faecal urinary urobilinogen
INTRAVASCULAR HAEMOLYSIS
- Haemglobinuria
- Urinary haemosiderin
- Methemalbbuminaemia
SUMMARY
- Increased reticuloyctes, LDH, unconjugated Bili
- Decreased haptoglobin
- Urine haemosiderin if suspecting INTRAVASCULAR haemolysis
- Difficult if liver disease
- DAT to confirm autoimmune
- Blood film
- If thrombocytopenia - look out for TTP
25
Cause of haemolysis
Intracorpuscular (Intrinsic) Defects
- Enzyme Deficiency: pyruvate kinase deficiency, G6PD
- Membrane or cytoskeletal defect: hereditary spherocytosis, hereditary elliptocytosis, PNH
- Hb Synthesis: sickle cell disease, haemoglobin C disease, thalassemia
- Acquired: Paroxysmal Nocturnal Haemoglobinuria
Extracorpuscular (Extrinsic) Defects
- Immune: Autoimmune haemolytic anaemia
- Microangiopathic: DIC, HUS, TTP, HELLP, prosthetic valve (non immune)
- Infections: Malaria, clostridium
- Hypersplenism
26
Compare laboratory findings for intravascular vs extravascular haemolysis
Elevated LDH
Elevated unconjugated bilirubin
Elevated reticulocytes
Decreased haptoglobin
INTRAVASCULAR (IHSc)
- Increased destruction of RBC within the blood vessels
CAUSES
- Toxins, eg: snake bites
- G6PD deficiency
- ABO incompatibility
- Complement mediated haemolysis: PNH
- Macroangiopathic anemia - mechanical destruction by prosthetic valve
- Microangiopathic anaemia - TTP, HUS, DIC, HELLP, SLE
- Blood Smear: SCHISTOCYTES
- Urine haemoglobin/hemosiderin: POSITIVE
- DAT NEGATIVE
EXTRAVASCULAR (EUSp)
- Increased destruction of RBCs by the reticuloendothelial system (primarily the spleen)
CAUSES
- RBC defects - sickle cell disease, spherocytosis, pyruvate kinase deficiency
- Autoimmune haemolytic anaemia
- PNH
- Blood smear: SPHEROCYTES
- Urine haemoglobin/hemsiderin: NEGATIVE
- Urobilinogen: POSITIVE
- DAT POSITIVE
27
Features of hereditary spherocytosis
- Autosomal dominant
- MCHC (mean cell haemoglobin concentration) increased (>360g/L)
- Primary defect in cytoskeleton of RBC membrane - defective spectrin and protein 4:1 interaction
- Results in spherocytes and increased osmotic fragility
- DAT negative
- Flow cytometry: eosin 5 malemide (EMA) binding
Management
- Folate supplementation
- Splenectomy
Red Cell Cytoskeleton: hereditary spherocytosis and hereditary elliptocytosis
28
G6PD Deficiency
- Glucose 6 phosphate dehydrogenase normally produces NADPH which is essential for converting oxidized glutathione back to its reduced form which protects RBCs from oxidative damage --> deficiency results in haemolysis of RBC (occurs in spleen, spherocytes occur)
- In the absence of reduced glutathione (e.g., due to G6PD deficiency), RBCs become susceptible to oxidative stress that can damage erythrocyte membranes, resulting in intravascular and extravascular hemolysis
- X linked inheritance
- Affects primarily males of African, Mediterranean, and Asian descent
Causes:
Acute haemolytic anaemia - in the setting of oxidant injury from:
- medications: antimalarial drugs (eg: chloroquine, primaquine), sulfa drugs (bactrim)
- illness - baxterial and viral infections
- food (eg: fava beans, legumes)
Clinical Features
- Sudden onset of back/abdominal pain, jaundice, dark urine, transient splenomegaly
- Acute haemolytic anaemia - in the setting of oxidant injury from medications, illness, food (eg: fava beans, legumes)
- Chronic haemolysis in severe disease
BLOOD SMEAR
- bite cells, blister cells, heinz bodies
Intravascular haemolysis
G6PD enzyme analysis
DAT negative
Note: Selective advantage in areas of endemic malaria: : As with sickle cell anemia, carriers of the G6PD deficiency may be less severely affected by malaria, especially if the disease is caused by Plasmodium falciparum
29
Liver disease and haemolysis
- In liver disease, already have raised LDH and bilirubin and low production of haptoglobin
- SPUR CELLS are seen in haemolysis in severe liver disease
30
Paroxysmal Nocturnal Haemoglobinuria
- Description
- Clinical Features
Physiologically, a membrane-bound glycosylphosphatidylinositol (GPI) anchor protects RBCs against complement-mediated haemolysis.
- Acquired clonal disorder of stem cells defective in PIG-A gene --> loss of enzymes (glycosyl-phosphatidyl-inositol GPI) that attaches surface proteins (CD55, CD59) to cell membranes (eg: erythrocytes, leukocytes, platelets) via the GPI anchor --> PNH cells more susceptible to complement mediated lysis (typically nocte due to lower pH)
CLINICAL FEATURES
- Cytopenia, aplastic anaemia
- Thrombosis in atypical locations - venous and arterial
- Smooth muscle dystonia
- Venous thrombosis, Budd chiari (hepatic vein thrombosis)
- Chronic intravascular haemolysis, dark urine
- Risk of developing MDS, aplastic anaemia
- Intermittent jaundice
- Vasoconstriction: headache, pulmonary HTN
- Abdominal pain, dysphagia
31
Paroxysmal Nocturnal Haemoglobinuria
- Investigations
- Management
INVESTIGATIONS
- Absence of CD55, CD59 and CD16 on cell surface of RBC/neutrophils
- Positive urinary haemosiderin - takes 24-48 hours to appear
- DAT negative
- Haemolysis
- Blood Film: SPHEROCYTES
MANAGEMENT
- Eculizumab - against C5, inhibits activation of terminal component of complement cascade
- Thrombosis: prophylaxis and if event anticoagulation if VTE
32
Indications/clues that may point to PNH
- Thrombosis with unusual features
- Unexplained Coombs-negative hemolysis and/or hemoglobinuria
- Consider performing as part of the workup for unexplained cytopenias, aplastic anemia, and myelodysplastic syndrome (MDS)
CATCH PNH by testing:
- Cytopenia
- Aplastic anemia
- Thrombois
- Coombs negative
- Haemoglobinuria
33
What is the mutation i Haemoglobin C disease?
B globin mutation - glutamate is replaced by lysine
In haemoglobin C disease, lyCine (lysine) replaces the amino acid glutamic acid
34
Autoimmune haemolytic anaemia
DAT POSITIVE
- Warm Autoimmune Haemolysis: IgG
- Cold Autoimmune Haemolysis: IgM
35
Warm Autoimmune Haemolytic Anaemia
A) WARM AUTOIMMUNE HAEMOLYSIS
- IgG antibodies react to protein on RBC at body temperature
- Most are idiopathic
- Blood film: SPHEROCYTES
CAUSES
- Malignancy: lymphoma, CLL
- Autoimmune: SLE
- Certain drugs: rifampin, phenytoin, penicillins, a-methyldopa
Warm weather is Great - IgG
TREATMENT
- Treat underlying associated disorders
Initial Therapy
- Steroids +/- Ritux
- DVT prophylaxis - high risk of DVT
- Folate supplement
- IVIG useful as adjunct
2nd line for persistent disease
- Splenectomy
- Mycophenolate/cyclophosphamide/azathioprine/PEX
36
Cold Autoimmune Haemolytic Anaemia
COLD AUTOIMMUNE HAEMOLYSIS
- Antibodies that recognise antigens on RBC at below core body temperatures causing agglutination of RBC, extravascular haemolysis
- Typically IgM ab (C3d only) which recruits components of the classical complementary pathway, C3b coated RBC engulfed by reticuloendothelial system
CAUSES
- Infectious mononucleosis (EBV)
- Mycoplasma pnuemonia
- Malignancy (CLL/non hodgkin), Waldenstrom macroglobulinaemia
CLINICAL FEATURES
- Cold induced symptoms: acrocyanosis (painful cyanosis of extremities), Raynauds, livedo reticularis, urticaria, cutaneous necrosis
Blood Film: RED CELL AGGLUTINATION
Haemolysis is intravascular so no spherocytes
Cold weather is MMMMiserable: Cold (IgM) AIHA is seen Malignancy (CLL), Mycoplasma pneumonia, Mononucleosis
TREATMENT
- Keep warm, steroids or splenectomy NOT effective
- For severe or symptomatic anaemia from active haemolysis - transfusion support and IVIG/PEX may be used as temporising measure
- Treat underlying cause
- Rituximab - but less efficient compared to when used in war
- Severe refractory cases - bortezomib, daratumumab, anti-complement
Note: splenectomy is not effective in cold as most extravascular haemolysis occurs in the liver
37
Features and disorders associated with microangiopathic haemolytic anaemia
Peripheral red blood cell fragmentation
- Polychromasia
- Thrombocytopenia
- Evidence of haemolysis - schistocytes
Disorders
- TTP
- HUS
- DIC
- HELLP
- Prosthetic valves
38
Features of TTP
Pentad:
1. MAHA - Microangiopathic hemolytic anaemia
2. Thrombocytopenia
3. Fever
4. Neurological manifestations: Headache/altered mental state
5. Renal failure
CAUSE
(a) ADAMTS-13 DEFICIENCY
- Cleaves the high molecular weight multimers of vWF
- Decrease in activity = accumulation of ultra large clumps of vWF multimers which binds to platelets leading to microvascular occlusion and thrombocytopenia
- Schistocytes form as erythrocytes are damaged by tangles of vWF and platelets
(b) Secondary: drugs such as quinine, cyclosporin, gemcitabine
DIAGNOSIS
- ADAMTS 13 <10%
- Schistocytes
- Haemolysis
Tx:
- Steroids – no evidence
- PLASMA EXCHANGE!
- FFP
- Rituximab – refractory or relapsing cases or even in patients with neurological and cardiac involvement
- Vincristine – refractory cases
39
Compare the red cell enzyme defects G6PD vs Pyruvate Kinase Deficiency
G6PD
- Hexose monophosphate pathway: pentose phosphate pathway
- Acute haemolytic crisis
- Susceptibility to oxidative stress
- X linked - common
Pyruvate Kinase Deficiency
- Glycolytic pathway
- Chronic haemolysis
- Reduced ATP formation - RBC rigidity
- Autosomal recessive: rare
40
Haemolysis Summary (DM)
INTRAVASCULAR
- Red cell fragmentation ( TTP - ADAMTS13 <10%)
- Paroxysmal nocturnal haemoglobinuria (flow cytometry for CD55, CD59)
EXTRAVASCULAR
- Autoimmune haemolytic anaemia - DAT
- Red cell membrane defects - blood film + flow cytometry
- Red cell enzyme defects - G6PD deficiency
41
Immune/Idiopathic Thrombocytopenic Purpura (ITP)
- Immune mediated thrombocytopenia
- Antibody mediated, platelet destruction by liver and spleen
- Reduced platelet half life with compensatory increase in marrow production
Ix:
- Isolated thrombocytopenia
- May present with mucocutaneous bleeding
- Diagnosis of exclusion
Associations
- AIHA
- CLL
- Autoimmune disease: RA/SLE
- H pylori
- Hep C
42
Treatment for ITP
- Aim of tx is to maintain platelet count high enough to prevent significant bleeding
- Observation if Plt >30
- First line: pred
- IVIG - more rapid response
- Splenectomy + vaccination - most effective therapy
Newer Drugs
- Romiplostim: TPO receptor agonist
43
Thrombocytopenia in pregnancy
(A) Gestational Thrombocytopenia
- 3rd trimester, spontaneous resolution
- Mild, platelets >80
- Pre-pregnancy plt count normal
- 5% of pregnancies
- Neonate unaffected
(B) ITP
- Earlier onset, may be more severe (<80), pre-existing low Plt
- Diagnosis of exclusion
- Tx: Pred, IVIG, monitoring and planning for delivery (36/40)
(C) HELLP/AFLP/DIC/pre-eclampsia
43
Thrombocytopenia in pregnancy
(A) Gestational Thrombocytopenia
- 3rd trimester, spontaneous resolution
- Mild, platelets >80
- Pre-pregnancy plt count normal
- 5% of pregnancies
- Neonate unaffected
(B) ITP
- Earlier onset, may be more severe (<80), pre-existing low Plt
- Diagnosis of exclusion
- Tx: Pred, IVIG, monitoring and planning for delivery (36/40)
(C) HELLP/AFLP/DIC/pre-eclampsia
44
Cause of target cells
The finding of target cells is nonspecific and may indicate various hemoglobinopathies, such as thalassemia, liver disease, or asplenia.
45
Causes of teardrop cells
Teardrop-shaped erythrocytes, known as dacrocytes, are found in conditions that involve extramedullary hematopoiesis (e.g., myelofibrosis, thalassemia, splenomegaly).
