Haematology Flashcards
Commonest 3 causes of malabsorption leading to iron deficiency anaemia in GI?
- Coeliac disease
- Gastrectomy
- H Pylori
Commonest 4 causes of occult blood loss leading to iron deficiency in GI?
- NSAIDs/Aspirin use
- Cancer- colon or gastric
- Benign gastric ulcer
- Angiodysplasia
When would you refer patients with a changed bowel habit for urgent colonoscopy?
40 years + and loose bowels + rectal bleeding for 6 weeks
60 years + rectal bleeding for 6 weeks
60 years + looser bowels for 6 weeks
Cause of megaloblastic macrocytic anaemia
Low B12
Low folate
Megaloblast= large immature nucleated RBC progenitor seen on blood films
Haemolysis causes what kind of anaemia?
Normocytic- normal MCV
For a patient with macrocytic anaemia, what four outcomes from bone marrow biopsy may arise and what causes do they indicate?
Megaloblastic- vit B12 + folate deficiency
Normoblastic- liver disease, hypothyroidism
Impaired erythropoesis- sideroblastic anaemia, aplasia, leukaemia
Increased erythropoesis- haemolysis
Producing odd cells (megaloblast), not producing enough or wiping them out
Patient has macrocytic anaemia, how can the cause be uncovered using investigations?
Blood film- hypersegmented polymorphs = vit B12 + folate deficiency
Target cells- liver disease
Sideroblasts (can also cause microcytic anaemia)
LFTs- may indicate alcoholism/liver problems
Raised bilirubin- haemolysis
TFTs- hypothyroidism
Bone marrow biopsy if still not elucidated (leukaemia, aplasia, haemolysis)
What is sideroblastic anaemia?
Bone marrow produces ringed sideroblasts rather than healthy red blood cells, granules of iron accumulate around the nucleus as a result of dysfunctional haem synthesis or processing.
Consider if iron-deficiency anaemia isn’t responding to iron supplements
3 common causes of a macrocytic anaemia:
B12/folate deficiency (megaloblastic)
Alcohol
Myelodysplasia
What is the inheritance of G6PD deficiency as a cause of haemolytic anaemia?
X linked, may be drug linked
What is different about the pathophysiology of thalassaemia compared to haemaglobinopathies like sickle cell, or HbC?
Thalassaemia = reduced rate of Hb synthesis (low MCV + MCH)
Others= abnormal Hb chains
Which clotting factor is implicated in haemophilia A?
Factor 8 (commoner than haemophilia B)
What chromosomal translocation is associated with Burkitt’s lymphoma?
8 + 14
Which translocation is associated with acute promyelocytic leukaemia
15 and 17
Which translocation is associated with CML and ALL (philadelphia chromosome)?
9 and 22
What defines anaemia in men and women?
Men- Hb < 135g/L
Women Hb < 115g/L
How can anaemia present?
Dyspnoea
Palpitations, angina (if coronary artery disease)
Fatigue, anorexia
Headache, faintness, tinnitus
Signs of anaemia:
<80g/L hyperdynamic circulation- tachycardia, flow murmurs (ejection systolic)
Conjuctival pallor
Iron deficiency: koilonychia, angular stomatitis, atrophic glossitis
Causes of microcytic anaemia:
MCV < 76
Low ferritin = Iron deficiency
High ferritin = Thalassaemia Sideroblastic anaemia (ineffective erythropoesis, more iron absorption)
Causes of normocytic anaemia:
MCV 76-96
Blood related: acute blood loss, haemolysis
Failures: renal, bone marrow, hypothyroidism
General: pregnancy, chronic disease
Causes of macrocytic anaemia:
MCV >96
Megaloblastic: B12 or folate deficiency
Drugs: cytotoxics, antifolates (phenytoin), alcohol excess
Haem related: myelodysplasia (variable cell production), marrow infiltration, reticulocytosis
Failures: liver failure, hypothyroidism
3 groups of causes of an iron deficiency anaemia:
Iron intake:
Diet (in babies + children, poverty)
Malabsorption (coeliacs, pancreatitis)
Blood loss (menorrhagia, GI bleeding, hookworm)
Patient has an iron deficiency anaemia and a history of menorrhagia. What is the next step?
Ferrous sulphate 200mg TDS
If old, or no obvious cause, a full GI work up of colonoscopy and gastroscopy is needed to exclude GI cancer
What is the pathophysiology of anaemia of chronic disease?
Hepcidin mediated: prevents iron overload
- Reduced production of erythropoietin
- Reduced response to erythropoietin
- Poor use of iron in erythropoiesis
- Cytokine-induced shortening of RBC survival
What different treatment can be tried for the different types of microcytic anaemia?
Iron deficiency- ferrous sulphate
Chronic disease- underlying disease and erythropoietin
Sideroblastic- pyridoxine ± transfusions
If iron is low, but ferritin is high what is the cause of the microcytic anaemia?
Anaemia of chronic disease:
Body tries to store iron away inside cells as ferritin to protect against bacteria so ferritin is high (acute phase response) and iron is low
Total iron binding capacity (transferrin levels) are low as there is enough iron, but it is not being effectively utilised
This is in contrast to iron-deficiency where iron will be low, but ferritin will also be low as there are not many iron stores and TIBC is high.
What is sideroblastic anaemia and how is it treated:
Abnormal haem synthesis or ineffective erythropoiesis leads to a microcytic anaemia with more iron absorption, iron loading in marrow, liver and heart
Histology: ring sideroblasts in the marrow- perinuclear ring of iron granules
Causes:
Congenital- x linked, rare
Acquired- idiopathic, following chemo/anti-TB drugs, EtoH, irradiation
IHx: ferritin (up), iron (up), TIBC (N)
Blood fil, marrow aspiration
Rx: cause + Pyridoxine ± transfusions
In haematinic studies of normocytic anaemias, what findings are expected for those with anaemia of chronic disease, chronic haemolysis and pregnancy?
All have high ferritin as all pro-inflammatory states
Anaemia of chronic disease- low iron (iron sequestered in cells), TIBC low (adequate iron levels, poorly utilised)
Chronic haemolysis- high iron (increased Hb breakdown) low TIBC
Pregnancy- high iron, high TIBC (more protein synthesis)
What is anicytosis and what causes it?
Variation in RBC size:
Megaloblastic anaemia (B12 or folate lack)
Iron deficiency anaemia
Thalassaemia
On blood film what abnormalities in RBC distribution may be seen and what causes it?
Irregular RBC collections = cold agglutinins
EBV, mycoplasma, SLE, CLL
Rouleaux formation = stacks
Inflammation, multiple myeloma
What types of poikilocytosis are seen on blood film in terms of membrane abnormalities and overall shape change?
Membrane abnormalities (liver disease or splenectomy)
Acanthocytes- spiculated RBCs from unstable membrane
Liver disease, spherocytosis, splenectomy
Burr cells- serrated smaller uniform RBC projections
Liver failure, renal failure, artifact
Target cells- increased surface area: volume ratio
Liver disease, haemaglobinopathy (more Hb), splenectomy
Cell shape:
Spherocytes- haeolytic anaemia or spherocytosis
Schistocytes- fragmented RBCs from TTP, DIC, heart valves
Teardrop cells- myelofibrosis, thalassaemia
Bite cells- oxidant sensitivity denatures Hb (Heinz bodies) then removed by spleen = G6PD
What intracellular extras might be seen in RBCs on a blood film and what causes them?
Basophilic RBC stippling: denatured RNA (defective Hb synthesis)
Megaloblastic anaemia, myelodysplasia, haemaglobinopathy, liver disease
Howell-Jolly bodies: DNA remnant (removed by spleen normally)
Megaloblastic anaemia, myelodysplasia, splenectomy
Heinz bodies: aggregates of denatured Hb (oxidant sensitivity)
G6PD or thalassaemia (extra Hb)
Pappenheimer bodies: granules of siderocytes containing iron
Sideroblastic anaemia, lead poisoning, splenectomy
Cabot rings: figure of 8 ?microtubules
Lead poisoning, pernicious anaemia
Causes of left shift vs right shift and what is it?
Shift describes overall proportions of stages of neutrophils
Left shift- more immature neutrophils (infection)
Right shift- more mature neutrophils (abnormal production of new neutrophils- megaloblastic anaemia, liver disease, uraemia)
Cause of blast cells on the blood film?
Leukaemia
Myelofibrosis
Malignant infiltration
Causes of neutrophilia:
Bacterial infection
Inflammation- MI, polyarteritis nodosa, disseminated cancer, stress (surgery, burns, haemorrhage)
Myeloproliferative disorders
Steroids
Causes of neutropenia:
Reduced production:
Chemo, carbimazole, sulphonamides, cytotoxics
Bone marrow failure
Increased destruction:
Viral infections, severe sepsis
Neutrophil antibodies- SLE, haemolytic anaemia
Hypersplenism- Felty’s (RA)
What is the hyper-eosinophilic syndrome?
Idiopathic disease where raised eosinophil count for 6 weeks leads to end organ damage resulting in:
Restrictive cardiomyopathy Skin lesions Thromboembolisms Lung disease Neuropathy Hepatosplenomegaly
Rx: steroids, anti-IL5 antibody biologic)
Causes of eosinophilia?
I MADeR
Infections: parasites, helminths
Malignant: lymphoma, eosinophilic leukaemia
Autoimmune: atopy, eczema, asthma, psoriasis, pemphigus, dermatitis herpetiformis, polyangitis nodosa, Loffler’s syndrome (pulmonary infiltration)
Adrenal insufficiency
Drugs reactions: erythema multiforme
How many lobes in a neutrophil’s nuclei is normal?
5 or less
Anymore = hypermature
A nucleus shaped like a horse shoe = band form = immature
What is a megaloblast?
A cell where the nucleus is delayed in it’s development compared to the cytoplasm of the same shape
What types of anaemia are seen in BM failure, myelodysplasia and marrow infiltration?
BM failure: making less RBCs, but the RBCs made are normal
= normocytic
Myelodysplasia: clonal progenitor cell dominates cell production, resulting in ineffective erythropoiesis and reduced RBCs
= normocytic (BM failure) or macrocytic (immature cells)
Marrow infiltration: pushes immature cells out earlier
= macrocytic
Investigations for a macrocytic anaemia:
LFTs- EtoH
B12/folate
TFTs- hypothyroidism
Blood film- membrane abnormalities (liver), intracellular extras (megaloblastic, myelodysplasia)
2nd line: bone marrow aspirate
Causes of folate deficiency
Poor intake: alcoholics, poverty
Malabsorption: coeliac disease, tropical sprue
Anti-folate drugs: methotrexate, anti-epileptics (phenytoin)
Increased use: more cell turnover (inflammation, cancer, haemolysis), pregnancy
How do antifolate drugs work?
Inhibit dihydrofolate reductase needed to produce folate
Folate acts a cofactor for enzymes producing purines and amino acids (like serine or methionine) so when synthesis is inhibited it reduces cell turnover and repair.
Examples:
Methotrexate (autoimmune conditions)
Pemetrexed (non-small cell lung cancer + mesothelioma)
Proguanil (protozoal DHFRi)
Trimethoprim (microbial DHFRi)
Phenytoin may compound these effects by inhibiting enzyme that enables uptake of folate in the gut
What needs to be given first B12 or folate, if patient is deficient?
B12 (alphabetical)
Can precipitate subacute combined degeneration of the cord
Pregnancy dose 400micrograms, unless high risk = 5mg
How is B12 absorbed?
Digestion releases B12 from it’s protein carrier (needs acidic environment to activate pepsin for cleavage)
Intrinsic factor in the stomach binds it
Complex absorbed in terminal ileum
Causes of B12 deficiency?
Lack of dietary intake- Vegans, alcoholics, elderly
Digestion of B12 from it’s protein carrier in the stomach requires acid for pepsin activation- PPIs, gastrectomy
Intrinsic factor- pernicious anaemia, atrophic gastritis
Absorption- ileal resection, Crohn’s, bacterial overgrowth, tapeworms
Signs of B12 deficiency:
Lemon tinge- anaemic pallor + mild jaundice (haemolysis)
Angular cheilosis
Glossitis
Features of B12 deficiency:
Neuropsych: depression, dementia, irritability, psychosis
Neurological: peripheral neuropathy, SCDC*, paraesthesiae
SCDC= dorsal column loss (LMN) + corticospinal (motor UMN)
Absent ankle + knee jerks with upgoing plantars
Ataxia + spastic weakness
What is pernicious anaemia?
Autoimmune atrophic gastritis leads to destruction of parietal cells- without which there is reduced intrinsic factor and acid secretion (and hence achlorhydria)
Resulting in low B12
May be caused by anti-parietal cell antibodies, anti-intrinsic factor antibodies
Patient has vitiligo and a macrocytic anaemia, what could be the cause?
Think autoimmune associated conditions:
Pernicious anaemia (B12 level) Hypothyroidism (TFTs- Hashimoto's or primary atrophic)
Tests and Rx in suspected pernicious anaemia?
IHx:
Anti-parietal cell Abs
Anti-intrinsic factor Abs
However may be -ve in 50%, so look at plasma B12 levels after IM if no PO response in B12 levels
NB: autoimmune unlikely in under 40s, suspect coeliac instead (duodenal biopsy)
Rx:
Malabsorptive cause: hydroxocobalamin IM then every 3 months
Dietry cause: oral B12 after initial hydrocobalamin
What is haemolysis and how can it’s causes be split?
Early breakdown of RBCs before their normal 120 day lifespan
Intravascular- in the circulation
Extravascular- in the reticuloendothelial system, macrophages of liver, spleen and bone marrow
What blood test results suggest haemolysis has taken place?
Normocytic or macrocytic (reticulocytic) anaemia
High unconjugated bilirubin
High urinary urobilinogen
High serum LDH (released from RBC breakdown)
How can an intravascular haemolysis be differentiated from extravascular?
Extravascular: splenomegaly
Intravascular:
High free plasma Hb
Presence of methaemalbuminaemia (Free Hb combines to albumin)
Low plasma haptoglobin (mops up free Hb, uptaken by liver)
Haemaglobinuria- red/brown urine but no RBCs
Haemosiderinuria- free Hb stored by tubular cells as haemosiderin, then sloughed off (Prussian blue stain 1 week post haemolysis)
Patient is jaundiced, which tests will enable diagnosis of haemolysis and confirm a cause?
Bloods: LFTs, conjugated + unconjugated bilirubin, LDH, haptoglobin levels, free Hb levels, methaemalbumin levels
Urine: urobilinogen, haemosiderin on microscopy, urine dip negative for RBCs despite red/brown urine
Blood film: thick + thin
Coombs test- direct antiglobulin test
Optional extras: osmotic fragility testing (membrane abnormalities) Hb electrophoresis (haemaglobinopathies) Enzyme assays (enzymatic causes)
Describe Coombs direct and indirect antiglobulin test:
Direct: wash patient’s RBCs
Add antihuman Abs
If RBC’s are coated by the patient’s anti-RBC antibodies, RBC will agglutinate
Indirect: get patient’s serum (containing anti-RBC ab’s potentially)
Add RBCs
Add anti-human Abs
RBC’s will agglutinate if serum has anti-RBC antibodies in
Patient has haemolysis and a positive Coombs test.
What could the 4 groups of causes be?
Acquired immune-mediated haemolysis:
- Drug induced: penicillin (binds membranes), quinine (forms complexes)
- Autoimmune: autoantibodies causing extravascular haemolysis (ie splengomegaly)
Warm AIHA- IgG binds at 37 degrees
Idiopathic, CLL, lymphoma, SLE
Cold AIHA- IgM binds <4 degrees, activates cell-surface compliment
EBV, mycoplasma - Paroxysmal cold haemoglobulinuria: Abs stick to RBCs when cold and cause self-limiting complement-mediated haemolysis on rewarming. Viruses + syphilis
- Isoimmune- transfusion reactions or haemolytic disease of newborns
How does the cause of warm autoimmune haemolytic anaemia and cold autoimmune haemolytic anaemia differ?
Warm AIHA: idiopathic, CLL, lymphoma, SLE, drugs
Cold AIHA: EBV, mycoplasma
Name 2 drugs causing autoimmune haemolytic anaemia (+ve Coombs test)?
Penicillin binds membranes
Quinine forms immune complexes
Rx for different types of autoimmune haemolytic anaemia depending on whether it is due to cold or warm agglutinins?
Warm AIHA: IgG mediated- steroids ± splenectomy (Extravascular haemolysis causes splenomegaly)
Cold AIHA: IgM mediated- Keep warm, chlorambucil maybe
What could cause an autoimmune haemolytic anaemia that was Coombs negative?
2% of AIHA
Autoimmune hepatitis (anti-SM)
Hepatitis B + C
Post flu or rituximab
Which conditions are considered microangiopathic haemolytic anaemias?
Where intravascular haemolysis occurs from mechanical trauma to RBCs resulting in schistocyte formation:
Haemolytic-uraemic syndrome (shiga toxin inactivates ADAM13)
Thrombotic thrombocytopenic purpura (autoantibodies against ADAM13, metalloprotease that cleaves vWF)
Disseminated Intravascular Coagulation (widespread clotting)
Pre-eclampsia + eclampsia (HELLP)
What is paroxysmal nocturnal haemoglobinuria?
Acquired mutation in haematopoietic stem cell/precursor
Abnormal surface glucosylphosphatidylinositol means complement is not removed from RBC surface
Leads to haemolysis, marrow failure (from clonal proliferation) and thrombophilia
IHx: immunophenotyping
Rx: anticoagulation, eculizumab (complement inhibitor)