AUTO - B. ANAEMIA-COVERED

Question 1

what is haematology

Answer 1

• blood = major organ/tissue

Question 2

what is blood made of

Answer 2

• RBCs: gas transport (45%)
• WBCs and platelets: immune and clotting (1%)
• plasma: water, electrolytes, glucose, lipids, drugs, plasma proteins etc (60%)

albumins: transport, colloidal osmotic pressure
globulins: transport, clotting, precursors to hormones, defense
fibrinogen: clotting

serum is coagulated plasma (blood plasma without the clotting factors)

Question 3

RBCs

Answer 3

• no nucleus
• contain haemoglobin for oxygen/carbon dioxide transport
• 120 days lifespan (short)
• fewer RBCs, less iron so can’t transport oxygen as well throughout body = anaemia (fatigue)

Question 4

synthesis of RBCs

Answer 4

• controlled by erythropoietin (EPO) = polypeptide hormone
• released by peritubular cells in kidney in response to hypoxia
  anaemia
  at altitude
  COPD
• EPO converts stem cells to RBCs
• renal disease = loss of EPO - renal anaemia
• recombinant EPO used

Question 5

Iron

Answer 5

• iron recycled (90%) from breakdown of RBCs in liver and spleen
• but need iron from diet to replace 10%
• iron uptake from GIT increased when iron deficient
  excess bleeding

Question 6

WBCs

Answer 6

• neutrophils (70%) - phagocytosis of microorganisms
• eosinophils (4%) - inflammation
• basophils (0.5%) - release histamine
• monocytes (6%) - phagocytic
• lymphocytes (B and T cells) (33%) - antibodies

Question 7

Platelets (thrombocytes)

Answer 7

• cellular fragments
• non-nucleated
• clot formation (co-aggulation)

Question 8

Blood counts

Answer 8

Measures
- RBCs/volume
- WBCs/volume
- haemoglobin (g per volume)
- mean corpuscular volume
- platelets/volume
- haematocrit (packed cell volume) - % that is RBC, dilution of blood causes decreased % (male - 40-52%, female - 36-48%)
- identify anaemias or infections

Question 9

Mean corpuscular volume

Answer 9

• mean size of RBCs
• microcytic anaemia: small (XS bleeding)
• macrocytic anaemia: large (VitB12 deficiency)
• normocytic anemia: normal

Question 10

what is anaemia

Answer 10

• reduced levels of Hb
• shortness of breath
• weakness/lethargy
• tachycardia
• nail bed and conjuctiva may be pale (not a reliable sign though) PALLOR
• glossitis (painful red tongue) and angular cheilitis (fissures at corner of mouth) - VIT B12 DEFICIENCY

Question 11

acute vs chronic bleed

Answer 11

• acute: rapid blood loss (haemorrhage),BP falls
  Overtime there is haemodilution
  so body compensates for decrease in BP by increasing fluid content in plasma
  leading to dilution of RBCs as not enough RBCs so haematocrit decreases
• chronic: long term bleeding (gastric bleeding, excessive menstruation)

Question 12

Treatment

Answer 12

• find and treat underlying cause
• oral iron (FeSO4) - constipation
• prophylaxis in pregnancy - oral iron
• transfusion (blood with more iron)

Question 13

pregnancy

Answer 13

• dilution and/or iron deficiency (increased demand for blood and iron to baby - microcytic)
• may be normocytic as pregnancy increases MCV but iron deficiency decreases MCV

Question 14

iron deficiency anaemia

Answer 14

• iron needed for Hb
• microcytic anaemia

caused by
- poor diet
- increased demand eg - pregnancy
- increased losses eg - menstruation
- GI bleeding: ulcers (NSAIDs) and colon cancer patients (50% present with anaemia)

Question 15

renal anaemia

Answer 15

• complicated chronic kidney disease
• loss of EPO so decreased production of RBCs and Hb levels
• normocytic anaemia
• Fe and EPO

Question 16

megaloblastic anaemia

Answer 16

• abnormal RBC maturation: large, immature RBCs (megaloblasts)
• impaired DNA synthesis
• macrocytic

symptoms
- anaemia
- jaundice due to breakdown of Hb, RBC not maturing and getting broken down easier and bilirubin produced, so XS Hb

causes
- vit B12 or folate deficiency (produce DNA)
- vegans at risk (B12 from animals)
- lack of intrinsic factor required for uptake of B12 (pernicious anaemia)

Question 17

pernicious anaemia

Answer 17

• lack of intrinsic factor for absorption of B12 due to autoimmune disease
• treat with vit B12 (hydroxocobalamin IM) - can’t give orally as don’t have intrinsic factor to help absorption of vit B12 so bypass we bypass GIT
• Crohn’s - malabsorption of B12, folate, iron

Question 18

haemolytic anaemias

Answer 18

• increased rate of RBC destruction
• genetic: abnormal reduction in RBC membrane protein (spectrum) so cells fragile
• acquired: malaria, drug induced

Question 19

sickle cell anaemia

Answer 19

• caused by SCD: genetic - SNP, change in genes produces abnormal Hb)
• abnormal Hb, insoluble forms crystals at low oxygen so RBC form sickle shapes and may block microcirculation (thinner, longer and don’t carry around as much oxygen)
• leads to haemolytic anaemia
• african/carribean background

Question 20

aplastic anaemia

Answer 20

• insufficient production of RBCs, WBCs and platelets (pancytopenia)
• problems with stem cells in bone marrow (side effect of anti-cancer drugs)
• decreased resistance to infections, increased bleeding, increased tiredness
• mostly acquired: viral, radiation, drugs (cytotoxic)

treatment:
- bone marrow transplant (tissue match)
- immunosuppressants (to prevent destruction of stem cells)
- colony-stimulating factors (to increase WBC count)

Question 21

polycythaemia (opposite to anaemia)

Answer 21

• increased Hb content and haematocrit
• increased blood viscosity - poor tissue perfusion

signs and symptoms
- ruddy appearance (redness of cheeks due to increased blood flow)
- cyanosis - blueing of toes and fingers (greater deoxygenation)
- headaches (decreased blood flow to brain)
- blurred vision
- hypertension (increased pressure in system)

caused by
PRIMARY
- changes in bone marrow, stem cell defect - cancer? increased production of RBCs caused by stem defect

SECONDARY
- increased EPO due to altitude, smoking, renal carcinoma

treatment for primary
- venesection (bleeding)
- radioactive phosphorous - myelosuppression (bone marrow suppression
- cytotoxic agents - myelosupression