Anaemia/blood disorders: Flashcards
Anaemia:
Definition: Reduction in the total number of circulating erythrocytes or a decrease in the quality or quantity of hemoglobin.
- Decrease in Haemoglobin
- RBC
- Haematocrit (% red cell volume))
- Symptoms of anemia based on HCT
Causes of Anaemia:
- Blood loss
- Impaired/defective/decreased erythrocyte production
- Altered haemoglobin synthesis (Fe def, thalassemia)
- Altered DNA synthesis (B12, folate)
- Increased erythrocyte destruction (EPO prolongs life of RBCs)
- Physiological anaemia of pregnancy – due to dilution of RBC’s – plasma volume increases 50% but RBC mass only 25%
- Stem Cell dysfunction ( aplastic anemia)
- Bone marrow infiltration (cancer)
- Renal disease (Kidneys make EPO, therefore renal disease - EPO)
Microcytic (low MCV)
- Fe deficiency
- Thalassemia
- Sideroblastic
- Chronic Disease
Macrocytic (large MCV)
- Vitamin B12
- Folate
- Drugs (chemo, methotrexate, AZT)
- Alcohol (suppresses BM)
Normocytic
- Blood loss
- Haemolysis
Iron (fe) deficiency
- Most common anaemia worldwide
- Particularly affects women
- Impairs oxygen carriage: Fe in haemoglobin binds to oxygen
Signs of Iron deficiency:
- Fatigue, SOB, lethargy, Pale ear lobes and palms
- impaired capillary circulation produces brittle, spoon - shaped nails
- sore tongue with atrophy of papillae
- Angular stomatitis (cracks at corner of mouth) due to altered epithelium
- Koilonychia
- Glossitis
Signs of Iron deficiency:
- Difficult swallowing due to web of mucous between pharynx and oesophagus.
- lesion may progress to malignancy
- Enzyme changes - gastritis, neuromuscular problems, irritability, headache, vasomotor problems.
- mental confusion, memory loss
- increased infections
Pernicious anaemia (vitamin B12)
- B12 from animal products in diet, also GIT micro-organisms.
- body stores last many years: depletion takes a long time
- Genetic autoimmune factors may be involves - parietal cell antibodies, type A chronic atrophic gastritis.
- Also, gastrectomy, pancreatitis.
Pernicious anaemia (vitamin B12) patho:
- Defective secretion of intrinsic factor in stomach
- If cannot bind B12 and protect it
- Vitamin B12 cannot be absorbed in ileum
- Malabsoption of B12 —- deficiency
- DNA synthesis impaired
- Defective red and white cell development in bone marrow —- megaloblasts, but Hb levels normal.
Pernicious anaemia (vitamin B12) patho :
- Neurological symptoms due to abnormal fatty acid production
- Myelin degenerates in spinal cord
- if untreated, B12 deficiency progresses to death from heart failure.
- increased risk of gastric carcinoma
Pernicious anaemia (vitamin B12) signs and symptoms :
- gradual onset, severe at presentation
- infections, GIT upset, kidney, heart problems (RS failure)
- Mood swings, memory loss, psychosis.
- Classic signs of anemia, e.g fatigue, paraesthesias (tingling, sensation/numbness), difficulty walking.
- anorexia, abdominal pain, weight loss, beefy tongue, lemon yellow skin.
Macrocytic Anaemia: Folic acid deficiency anaemia
Folic acid important not only for RBC development but also for proper closure of the neural tube.
- when the neural tube does not close completely, an NTD develops.
- A NTD is an opening in the spinal cord or brain that occurs very early in human development (2nd week of pregnancy)
- Spina bifida is an example of a NTD.
- deficiency most common in later pregnancy but effects are most significant during the first trimester
- treatment — eat folic acid rich foods
Congenital Anemias
Thalassemia
ALPHA
BETA
Features of thalassaemia
- Normal adult Hb– 2X alpha (a) and 2X beta (b) chains
- Thalassaemia: group of inherited disorders characterised by
reduced or absent synthesis of either
a or b globin chains - Unequal quantity of chains: excess of non
-deficient chains – ineffective red cell production - Extra chains aggregate & precipitate within cells
- Cells prone to haemolysis or Destruction in the bone marrow or spleen
Thalassemia:
Inherited anemia caused by decreased
synthetic rate of hemoglobin α or β
chains
two forms: Alpha and Beta thalassemia
Beta Thalassemia:
Pathogenesis
- point mutations in 1 or 2 beta genes
- decreased hemoglobin production
- hemolysis of red cells in marrow and bloo
Beta Thalassemia - Clinical Features
Heterozygous -- mild anemia Homozygous (Cooley anemia) -- severe anemia in infancy -- facial and cranial bone enlargement -- splenomegaly -- secondary hemochromatosis
Beta Thalassemia
Pathology
- microcytic anemia
- target cells
- basophilic stippling
- elevated Hb A2 (α 2 δ 2) in heterozygotes
- elevated Hb F (α2γ2) in homozygotes
Alpha Thalassemia:
1 - None = Silent carrier
2 - Mild = α-thal trait
3 - Moderate = Hemoglobin H disease (β4)
4 - Severe = Hemoglobin Barts disease (γ4)
