Haematology Flashcards
Hb Value Anaemia - Men and women?
Men: <13.5
Women: <11.5
Symptoms anaemia?
Fatigue Dyspneoa Faintness Palpitations Headache Tinnitus
Signs anaemia?
May be absent even in severe.
Pallor
Hyperdynamic circulation: Tachycardia, flow murmur (apical ESM), cardiac enlargement
Causes microcytic anaemia?
Iron-deficiency anaemia = the most common cause:
Thalassaemia (suspect if the mcv is ‘too low’ for the Hb level and the red cell count is raised, though definitive diagnosis needs dna analysis)
Sideroblastic anaemia
NB. Thal and sideroblastic both have increased serum iron and ferritin, with low TIBC (iron accumulation)
Would would this suggest?:
microcytic anaemia
increased serum iron and ferritin
low total iron-binding capacity
Thalassaemia or Sideroblastic anaemia (iron accumulation)
Causes of normocytic anaemia?
1 Acute blood loss. 2 Anaemia of chronic disease (or ↓mcv). 3 Bone marrow failure. 4 Renal failure. 5 Hypothyroidism (or ↑mcv). 6 Haemolysis (or ↑mcv) e.g. hereditary spherocytosis 7 Pregnancy.
What would this suggest?
Normocytic anaemia
↓wcc or ↓platelets
Marrow failure
Causes macrocytic anaemia?
1 B12 or folate deficiency. 2 Alcohol excess—or liver disease. 3 Reticulocytosis (eg with haemolysis). 4 Cytotoxics, eg hydroxycarbamide. 5 Myelodysplastic syndromes. 6 Marrow infiltration. 7 Hypothyroidism. 8 Antifolate drugs (e.g. phenytoin, methotrexate).
What is haemolytic anaemia?
Increased RBC breakdown
What is reticulocytosis?
Anaemia with increased MCV and polychromasia
Signs of haemolytic anaemia?
Reticulocytosis Mild macrocytosis ↑bilirubin ↑ldh ↑urobilinogen Bile pigment stones Mild jaundice (pre-hepatic) so no bili in urine
How would you give a transfusion in severe anaemia with heart failure?
SLOWLY
+ 10-40mg furosemide IV/PO with alternate units
Reassess for fluid overload regularly - JVP, basal crackles
Causes iron-deficiency anaemia?
Blood loss, eg menorrhagia or GI bleeding
Poor diet or poverty in babies or children (but rarely in adults).
Malabsorption (eg coeliac disease) is a cause of refractory ida.
In the tropics, hookworm (gi blood loss) is the most common cause.
Signs chronic iron deficiency anaemia?
- Koilonychia (spoon-shaped)
- Atrophic glossitis (smooth, painful tongue)
- Angular cheilosis/stomatitis
Ix iron deficiency anaemia? + Their results
- Blood film: Microcytic, hypochromic. Poikilocytosis (various abnormal shapes RBC). Anisocytosis (variety in RBC sizes)
- Coeliac screen
- Haem studies: ↓ferritin, ↓transferrin saturation, ↑TIBC
NB. Ferritin is acute phase protein so ↑ c infection etc. - Urgent gastroscopy and colonoscopy
Mx iron deficiency anaemia? SE of treatment?
Ferrous sulphate 200mg PO TDS
SE: GI upset - nausea, diarrhoea/constipation, black stool
Continue for at least three months after Hb normal.
What is sideroblastic anaemia?
Ineffective erythropoiesis, leading to ↑iron absorption, iron loading in marrow (ringed sideroblasts) ± haemosiderosis (endocrine, liver, and heart damage due to iron deposition).
Causes sideroblastic anaemia?
- Congenital (rare, x-linked)
- Acquired:
myelo-dysplastic/myeloproliferative diseases
drugs: chemotherapy, anti-TB drugs, irradiation, alcohol or lead excess.
Ix sideroblastic anaemia? And results?
Blood film: Microcytic hypochromic, ringed sideroblasts in marrow
Plasma: ↑ferritin, ↑iron, ↔ TIBC
Mx sideroblastic anaemia?
Remove cause
Pyridoxine ± repeated transfusions for severe anaemia
What could cause macrocytosis without anaemia?
Alcohol
Myeloma (paraproteins)
Hyperglycaemia
Causes macrocytosis?
Megaloblastic (Impaired DNA synth): B12 and folate deficiency. Cytotoxic drugs: Methotrexate, Phenytoin
Non-megaloblastic: Fatty deposits RBC - EtOH or liver disease, hypothyroidism, pregnancy
Causes folate deficiency?
How long do body stores last?
- Poor dietary intake
- Increased demand: pregnancy, haemolytic, malignancy
- Malabsorption: Coeliac, Crohns
- Drugs: EtOH, Phenytoin, Valporate, Trimethoprim, Methotrexate
Around 4 months
Treatment folate deficiency?
Assess underlying cause
Folic acid 5mg/day for 4 months, with B12 unless known normal
Why don’t you give folate without B12?
In low B12 states can precipitate/worsen subacute combined degeneration cord
Causes B12 deficiency?
- Dietary (e.g. vegans - in meat, fish and dairy)
- Malabsorption:
lack of intrinsic factor (IF) - binds B12 in the stomach, enabling it to be absorbed in the terminal ileum.
or problems terminal ileum (ileal resection, Crohn’s disease, bacterial overgrowth, tropical sprue, tapeworms). - Congenital metabolic errors
Features B12 deficiency?
Symptoms anaemia
‘Lemon tinge’ to skin - pallor (anaemia) and mild jaundice (due to haemolysis)
Glossitis (beefy-red sore tongue_
Angular cheilosis
Neuro: Irritability, depression, psychosis, dementia Peripheral neuropathy Paraesthesia Sub-acute combined degeneration cord
What are the features of subacute combined degeneration of the cord?
Peripheral sensory neuropathy, with both UMN and LMN signs due to ↓B12.
Classic triad:
• extensor plantars (UMN)
• absent knee jerks (LMN)
• absent ankle jerks (LMN).
Symmetrical signs
Insidious onset
Pain and temperature intact (spinothalamic)
Joint-position and vibration sense are often affected first leading to ataxia, followed by stiffness and weakness if untreated.
What is pernicious anaemia?
Autoimmune condition, autoAbs to parietal cells. Atrophic gastritis (loss of glandular cells) leads to a lack of IF secretion. Dietary B12 therefore remains unbound and conseqeuently cannot be absorbed by the terminal ileum.
Why have a low threshold for upper GI endoscopy in pernicious anaemia?
Stomach carcinoma 3x more common
What are the two types of autoimmune haemolytic anaemia?
Warm
Cold
= Optimum binding temperature to RBC
What class of autoantibody is responsible for warm autoimmune haemolytic anaemia? What is the optimum temperature?
IgG
Body temperature, 37 degrees
What class of autoantibody is responsible for cold autoimmune haemolytic anaemia? What is the optimum temperature?
IgM
<4 degrees
Causes warm autoimmune haemolytic anaemia?
Idiopathic
SLE
RA
Causes cold autoimmune haemolytic anaemia?
Idiopathic
Following infection
Ix and Mx warm autoimmune haemolytic anaemia?
DAT +ve
Steroids/immunosuppressants
+/- splenectomy
Ix and Mx cold autoimmune haemolytic anaemia?
DAT +ve complement only
Keep warm
Cholarmbucil
What is paroxysmal cold haemoglobinuria?
Cause?
Rare. Associated with viruses, esp. measles, mumps, chickenpox
Donath-Landsteiner antibodies stick to RBCs in cold, causing self-limiting haemolysis on rewarming
What is paroxysmal nocturnal haemoglobinuria?
Rare, acquired stem cell disorder with haemolysis (esp at night), marrow failure and thrombophilia
What is the inheritance of G6PD deficiency? How would you test for it? How long would you need to wait after a crisis to get results?
X-linked
Enzyme assay
>8 weeks as young RBCs may have enough enzyme - normal result
What happens in G6PD deficiency attacks? - Why?
What would you see on a film?
What may precipitate an attack?
Oxidative crisis - rapid anaemia and jaundice. Due to ↓glutathione production
Precipitated by: drugs (eg primaquine, sulfonamides, aspirin), exposure to Vicia faba (broad beans/favism), or illness. Henna
Film: Bite and blister cells
What is the inheritance of pyruvate kinase deficiency?
Mechanism?
Autosomal recessive
↓ATP production causes ↓RBC survival. Rigid RBC phagocytosed in spleen.
Signs/symptoms pyruvate kinase deficiency?
Homozygotes have neonatal jaundice; later, haemolysis - anaemia with splenomegaly ± jaundice.
Ix and Mx pyruvate kinase deficiency?
Ix: Pyruvate kinase assay
Mx: Often not needed. Transfusion or splenectomy
What is the inheritance of hereditary spherocytosis?
Pathophysiology?
Autosomal dominant. Commonest inherited haemolytic anaemia N europe
Path: defect in RBC membrane, less deformable, spherical so get trapped in spleen and haemolysed
Signs, Ix and Mx hereditary spherocytosis?
Signs: Splenomegaly, jaundice
Ix: Blood film, DAT (-ve)
Mx: Folate, splenectomy after childhood
Inheritance sickle-cell anaemia?
Autosomal recessive
What is the mutation in sickle-cell anaemia?
Glu-> Val at position 6 on B chain Hb. Produces HbS instead of HbA
What are the different phenotypes sickle-cell anaemia?
Which are significant?
HbSS - Homozygote
HbAS - Sickle-cell trait. No disability, protective from malaria. - May have symptomatic sickle if hypoxic - unpressurised aircraft or anaesthetic
What is the pathogenesis sickle-cell anaemia?
HbS polymerises when deoxygenated - deforms RBC to sickle shape - fragile and haemolyse. Also block small vessels.
What Ix in sickle-cell anaemia?
How would you distinguish between SS and AS?
Blood film: Sickle cells and target cells
Sickle solubility test +ve in both
Hb electrophoresis: confirms diagnosis and distinguishes
What is the Mx of a sickle-cell crisis?
General: - Analgesia - Rehydrate - O2 as required - Keep warm - Abx if raised temp or chest signs - Crossmatch Ix: - Septic screen - FBC and reticulocyte count
Mx:
- Transfuse if required
- Exchange transfusion if severe
What would be the indications for exchange transfusion in sickle crisis?
Rapidly worsening
- Severe chest crisis
- Suspected CNS event
- Multiorgan failure
What are the triggers of vaso-occulsive crisis in sickle-cell anaemia?
- Infection
- Cold
- Hypoxia
- Dehydration
What are the features of vaso-occulsive crisis in sickle-cell anaemia?
S splenomegaly I Infarction: stroke, spleen, AVN, leg ulcers, avascular necrosis fem head, BM C crises: pulmonary, mesenteric, pain K kidney disease L liver, lung disease E erection D dactylitis (in young children)
What is an aplastic crisis in sickle cell?
Cause?
Sudden reduction in marrow production, due to parvovirus B19.
Usually self-limiting, transfusion PRN
Complications of sickle cell?
Splenic infarction (<2 years age). Increases infection susceptibility Poor growth Chronic renal failure Gallstones Retinal disease Iron overload (transfusions) Lung disease
Mx chronic sickle cell?
Hydroxycarbamide if frequent crises (inc HbF)
Pencillin V BD and immunisations - splenic infarction
Folate
Causes increased APTT?
Lupus anti-coagulant
Haemophilia
What is a thalassaemia? How does this cause problems?
Underproduction/no production of one globin chain.
Unmatched globins precipitate, damage RBC membranes leading to haemolytic
What is B thalassaemia minor/trait?
Consequences?
Heterozygous, carrier state.
Usually asymptomatic - mild, well tolerated anaemia that may worsen in pregnancy
What is B thalassaemia intermedia?
Consequences?
Intermediate state with moderate anaemia, not requiring transfusions.
May be splenomegaly.
- Mild homozygous B mutations
- Co-inheritance of B thal trait with other Hb-opathy e.g. HbC, HbB+ or sickle - B+
What is B thalassaemia major?
Consequences?
Homozygous state. Significant abnormalities both B-globin genes
Presents in 1st year with severe anaemia and failure to thrive.
- Skull bossing
- Hepatosplenomegaly
- Osteopenia
Why do you get skull bossing in B thalassaemia major?
Extra-medullary haematopoeisis
Mx B thalassaemia major?
Regular (2-4 weekly) transfusions Iron-chelators Splenectomy as required Hormone replacement Marrow transplant is only cure
What causes the alpha thalassaemias?
Mainly gene deletions
N: aa/aa
In a thalassaemia, what is HbH disease? Consequences?
–/-a - Three alpha gene deletion
Named because of the formation of B tetramers (HbH) on blood film (excess B chains)
Moderate anaemia
Features of haemolysis: hepatosplenomegaly, leg ulcers, jaundice
In a thalassaemia, what is the consequence of 1 or 2 gene deletion?
2 gene deletion: –/aa or -a/-a is an asymptomatic carrier state with decreased MCV
Single gene deletion gives a normal clinical state
What is the deficiency in Haemophilia A?
How is it inherited?
Factor VIII
X-linked recessive
How is Haemophilia A diagnosed?
When and how does it present?
Diagnosis: ↑APTT and ↓factor VIII assay. Normal PT
Presentation variable depending on severity - often early in life or after trauma - bleeds into joints cause crippling arthropathy, bleeds into muscles cause haemotomas
Mx Haemophilia A? Major/minor bleeds?
Avoid NSAIDs and IM injections
Minor bleeds: Pressure, elevation. Desmopressin + tranexamic acid
Major: Recombinant factor VIII
What is the deficiency in Haemophilia B?
How is it inherited?
Factor IX deficiency
X-linked recessive
Presentation and Mx Haemophilia B?
Clinically behaves like Haemophilia A.
Mx: Recombinant factor IX
What is acquired haemophilia?
Rare autoimmune bleeding disorder.
Autoantibodies are most frequently against factor VIII