Haematology Flashcards
normal Hb for males?
130-180g/L
what is the mean corpuscular volume (MCV)
the average volume of the erythrocytes
what is the mean corpuscular haemoglobin (MCH)
average mass of Hb per RBC
what is the mean corpuscular haemoglobin concentration (MCHC)
average conc of Hb in a given volume of blood
definition of red cell distribution width
measurement of the variability of the RBC size
what is the reticulocyte count
number of immature RBC in circulation - normally ~1%
a rise indicates rapid RBC production
what is the mean platelet volume (PMV)
average platelet size
what is a tear drop elliptocyte?
oval and elongated - associated with beta-thalassaemia
what is a pencil cell?
pencil shaped - associated with hereditary elliptocytosis
what is a hypochromic cell?
RBC is paler than normal - associated with iron deficiency anaemia
define normocytic normochromic
RBCs are average size and Hb is within normal limits
define anisocytosis
RBCs are unequal in size
define poikilocytosis
RBCs are unequal in shape
define microcytosis
RBCs are abnormally small
causes of normocytic normochromic anaemia
acute blood loss haemolytic anaemia aplastic anaemia G6PD deficiency HbS hereditary spherocytosis acute bood loss CKD
causes of microcytic hypochromic anaemia
"TAILS" thalassemia anaemia of chronic disease iron deficiency anaemia lead poisoning sideroblastic
causes of macrocytic normochromic anaemia
"FAT RBC" folate deficiency alcohol thyroid (hypothyroid) reticulocytosis B12 deficiency/ pernicious anaemia cytotoxic drugs - methotrexate, azathioprine
where in the fetus are RBCs produced?
initially the yolk sac
then the liver and spleen
and finally the bone marrow
where are RBCs produced in a healthy adult?
the bone marrow in the vertebra, ribs, sternum, sacrum, pelvis and proximal ends of the femur
common symptoms of anaemia
breathlessness
chest pain/ angina like symptoms
fatigue
physiological adaptations to anaemia
increased CO
reduced Hb O2 affinity due to increased 2,3 DPG
redistribution of blood flow
what may cause a raised reticulocyte count?
autoimmune haemolysis acute leukaemia folate deficiency anaemia of chronic disease acute blood loss HbS splenic sequestration
name some immune haemolytic anaemias
autoimmune haemolytic anaemia haemolytic disease of the newborn thrombotic thrombocytopenia purpura anaemia associated with pre-eclampsia drug associated anaemia
what is seen on a post-splenectomy blood film?
Howell-Jolly bodies
Pappenheimer bodies
Target cells
Irregular contacted erythrocytes
Sickle cell crises
- thrombotic, ‘painful crises’
- sequestration
- aplastic
- haemolytic
Rx: hydroxycarbamide if frequent crises
Thrombotic crises
also known as painful crises or vaso-occlusive crises
precipitated by infection, dehydration, deoxygenation
infarcts occur in various organs including the bones (e.g. avascular necrosis of hip, hand-foot syndrome in children, lungs, spleen and brain
Sequestration crises
sickling within organs such as the spleen or lungs causes pooling of blood with worsening of the anaemia
acute chest syndrome: dyspnoea, chest pain, pulmonary infiltrates, low pO2 - the most common cause of death after childhood
Aplastic crises
caused by infection with parvovirus
sudden fall in haemoglobin
Haemolytic crises
rare
fall in haemoglobin due an increased rate of haemolysis
Sickle cell anaemia
HbS
autosomal recessive common in Afro-Caribbean populations
A–>T base mutation causing a polar glutamate to a non-polar valine substitution in beta chains of Hb
deOHb polymerise, become fragile and haemolyse, sickle shaped RBC get stuck in small vessels and cause an infarction
heterozygous state is protective against malaria
pernicious anaemia
anti-intrinsic factor antibodies bind to intrinsic factor of gastric parietal cells in gastric fundus - leads to poor vitamin B12 absorption and hence deficiency
where is iron, folate and B12 absorbed in the GIT?
“dude is just feeling ill, bro”
Duodenum - iron
Jejunum - folate
Ileum - vitamin B12
glucose-6-phosphate dehydrogenase deficiency
is the commonest RBC defect
X-recessive
many drugs can precipitate a crisis as well as infection and fava beans
deficiency of G6PD = low glutathione = increased cell susceptibility to oxidative stress
HEINZ BODIES ON BLOOD FILM
types of polycythaemia
apparent or relative - due to decreased plasma volume (dehydration/burns/stress)
absolute polycythaemia - polycythaemia (rubra) vera or secondary polycythaemia
polycythaemia rubra vera
is a myeloproliferative disorder caused by clonal proliferation of a marrow stem cell leading to an increase in red cell volume and overproduction of neutrophils and platelets
JAK2 mutation in 95% of patients
peak incidence in 6th decade
features: headache, dyspnoea, blurred vision, night sweats, pruritis (worse after a hot bath), hyper-viscosity, haemorrhage (due to abnormal platelet production), plethoric appearance (ruddy cyanosis)
treatment: aspirin, venesection (1st line - iron deficiency may limit erythropoiesis, doesn’t control the platelets), daily hydroxyurea (increases risk of leukaemia) or phosphorous-32 therapy (a single dose causes remission for two years)
prognosis - 5-15% myelofibrosis, 5-15% acute leukaemia
secondary polycythaemia
- caused by compensatory increase in EPO; high altitudes, respiratory diseases (COPD, obstructive sleep apnoea), CVS disease (especially congenital with cyanosis), increased Hb affinity, heavy cigarette smoking
- caused by inappropriate EPO increase: renal disease or tumours
Haemophilia A
factor VIII deficiency
X-linked recessive
(Ix: increase APTT and reduced factor VIII assay)
Rx: avoid NSAIDs and IM injections
minor bleeds - desmopressin (increases factor VIII)
if bleeding use recombinant factor VIII to increase levels to a % of normal (50% if major bleed, 100% if life-threatening)
Haemophilia B
factor IX deficiency
X-linked recessive inheritance
Rx: recombinant factor IX
von Willebrand’s disease
most common inherited bleeding disorder
autosomal dominant
lack of von Willebrand factor (which promotes platelet adhesion and is a carrier molecule for factor VIII)
Ix: increased APTT, increased bleeding time, reduced factor VIIIc, defective platelet aggregation with ristocetin
Rx: avoid NSAIDS, use tranexamic acid for mild bleeds, desmopressin (induces release of vWF), if major bleeds or surgery - vWF-containing factor VIII concentrate
disseminated intravascular coagulation (DIC)
release of procoagulants into circulation causes widespread activation of coagulation, consuming clotting factors and platelets and hence increasing risk of bleeding
Ix: reduced fibrinogen (correlates with severity), raised d-dimer
blood film: schistocytes
Rx: FFP (to replace coagulation factors), cryoprecipitate (replace fibrinogen)
Multiple myeloma
neoplasm of the bone marrow plasma cell
features: CRABS –> calcium high, renal insufficiency, anaemia (normocytic normochromic), bone pain and pathological fractures (especially of the vertebrae)
bence-jones proteins in urine
blood film - rouleaux
rX: analgesia, bisphosphonates, orthopathic procedures, transfusions or EPO, fluids, ABx if infection, regular IV immunoglobulin infusions if recurrent
hypercalcaemia in myeloma pathophysiology
primarily due to increased osteoclastic bone reabsorption due to local cytokines (IL-1 and TNF) released by myeloma cells
also contributing is the impaired renal function, increased renal tubular calcium reabsorption and increased PTH-rP levels
acute lymphoblastic leukaemia
most common malignancy in children (2-5y/o) 70-90% cure rate in children
immature cells of B or T cell lineages
blast cells on blood film and in bone marrow
lumbar puncture required to look for CNS involvement
Rx: blood/platelet transfusion, allopurinol (prevents tumour lysis syndrome), IV ABx for infections
acute myeloid leukaemia
most common acute leukaemia in adults
death in 2 months if untreated as is rapidly progressive
has Auer rods and immature cells
chronic myeloid leukaemia
Philadelphia chromosome is found in 95% of patients
proliferation of myeloid cells
causes splenomegaly and subsequent abdominal discomfort
median survival is 5-6 years
Rx: imatinib, hydroxyurea, interferon-alpha, allogenic bone marrow transplant
chronic lymphoblastic leukaemia
proliferation well-differentiated (B) lymphocytes
often an incidental finding
blood film: smudge/smear cells
2/3 undergo Richter’s transformation - become high-grade fast growing non-Hodgkin’s lymphoma when reaches the lymph nodes
Hodgkin’s lymphoma
Reed-Sternberg cell
alcohol consumption can cause severe pain
nodular sclerosing is the most common type ~70%
“B” symptoms predict a poor prognosis - weight loss (>10% in 6 months), fever >38, night sweats, lymphocyte depleted type also worsens prognosis
Rx: chemotherapy and radiotherapy –> one of the most treatable cancers (lymphocyte predominant improves prognosis)
Non-Hodgkin’s lymphoma
can be a result of Richter’s transformation
Rx: rituximab, stem cell transplantation, multiple nodal group resection
modifiable VTE risk factors
smoking immobility dehydration hyperlipidaemia COCP, HRT (stop OCP 4 weeks prior to surgery) olanzapine
non-modifiable VTE risk factors
increasing age femal trauma/surgery (the stress response) AF blood abnormalities malignancy thrombophilia
what is the most common thrombophilia in the UK?
Factor V Leiden (activated protein C resistance) is the most common inherited thrombophilia, being present in around 5% of the UK population.
LMWH MOA
e.g. dalteparin/enoxaparin
inactivates factor Xa
unfractionated heparin MOA
binds to antithrombin, increasing its ability to inhibit thrombin, factor Xa and IXa
warfarin MOA
inhibits the reductase enzyme responsible fore regenerating active vitamin K
reversed by vitamin K
dabigatran MOA
direct thrombin inhibitor
mainly renally excreted
can be reversed by idarucizumab (praxabind)
rivaroxaban MOA
direct factor Xa inhibitor
mainly hepatic excretion
apixaban MOA
direct factor Xa inhibitor
mainly faecal excretion
aspirin MOA
irreversible, non-selective COX-(1) inhibitor
stop 7 days pre-op
clopidogrel MOA
blocks P2Y1Z so increases cAMP which prevents platelet aggregation
stop 5 days pre-op
dipyridamole MOA
phosphodiesterase inhibitor, increases cAMP so inhibits platelet aggregation
why are transfusions sometimes irradiated?
to get rid of T-cells to prevent GvHD e.g. if pt has Hodgkin’s lymphoma
consequences of a transfusion reaction
"GOT A BAD UNIT" Graft vs Host disease Overload Thrombocytopenia Alloimmunization Blood Pressure unstable Acute haemolytic reaction (Rx: immediate transfusion termination, fluid resus and inform lab) Delayed haemolytic reaction Urticaria (Rx: temporarily discontinue transfusion and give antihistamines) Neutrophilia Infection Transfusion associated lung injury
Rx: for severe allergic reaction/anaphylaxis: permanent discontinuation of transfusion, IM adrenaline, supportive care, antihistamines, corticosteroids and bronchodilators
post thrombotic syndrome
painful heavy calves, pruritus, swelling, varicose veins, venous ulceration
–> compression stockings
