Week 1 part 3 Flashcards
When hemolysis occurs and leads to a red blood cell imbalance, it is called hemolytic anemia, and there are two types: what are the two types?
Intrinsic and extrinsic (intravascular and extravascular hemolysis)
Intrinsic hemolytic anemia
Inherited hemolytic anemia (also called intrinsic hemolytic anemia) is caused by a defect in the red blood cells themselves and result when one or more genes that control red blood cell production don’t function properly. With these conditions, red blood cells are destroyed earlier than normal
Extrinsic hemolytic anemia
The spleen destroys healthy red blood cells or they are damaged by an infection, tumors, autoimmune disorders, medication, leukemia, or lymphoma.
Consequences of haemolysis
Erythroid hyperplasia (increased bone marrow red cell production) Excesss red cell breakdown products (e.g. billirubin)
COMPENSATED HAEMOLYSIS
Increased red cell destruction compensated by increased red cell production
i.e. Hb Maintained
HAEMOLYTIC ANAEMIA
Decompensated haemolysis
Increased rate of red cell destruction exceeding bone marrow capacity for red cell production
i.e. Hb Falls
Polychromasia
Polychromasia is the presentation of multicolored red blood cells in a blood smear test. It’s an indication of red blood cells being released prematurely from bone marrow during formation.
Intravascular & extravascular hemolysis
Intravascular hemolysis occurs when erythrocytes are destroyed in the blood vessel itself, whereas extravascular hemolysis occurs in the hepatic and splenic macrophages within the reticuloendothelial system.
Extravascular hemolysis consequences
Hyperplasia in spleen and liver (hepatosplenomegaly)
Release of protoporyphrin (jaundice and gall stones)
Intravascular hemolysis consequences
Haemoglobinemia ( due to red cells destroyed in blood vessells and dropping their contents such as HB)
Methaemalbunimea, haemoglobinurea (pink urine), Haemosiderinurea
Causes of intravascular hemolysis
Incompatible ABO transfusions
G6PD defiency
severe falciparum malaria
Autoimmune hemolytic anemias
Autoimmune hemolytic anemia is caused by autoantibodies that react with red blood cells at temperatures ≥ 37° C (warm antibody hemolytic anemia) or < 37° C (cold agglutinin disease). Hemolysis is usually extravascular. The direct antiglobulin (direct Coombs) test establishes the diagnosis and may suggest the cause
Direct Coombs test
Identifies autoantibodies bound to patients own red cells - such as in warm (IgG) and cold (IgM) hemolytic anemias.
Alloimmune hemolyis
Alloantibodies - hemolytic transfusion reactions - can be immediate (IgM - mainly intravascular reaction & life-threatening) or delayed reaction (IgG - mainly extravascular & could be due to previous sensitisation)
Mechanical hemolytic (acquired) anemias
When mechanical trauma breaks down red blood cells such as through a blood vessel or leaking heart valve.
What happens to transferrin levels when iron is high?
transferrin saturation increases
What happens to transferrin levels when iron is low?
Transferrin sats decrease
What happens to ferritin levels when iron is low?
Ferritin (storage molecule for iron) decreases
Sideroblastic anaemia
- excess iron build up in mitochondria (blue granules around nucleus) due to failure to incorporate iron in to haem. Can be hereditary or acquired eg MDS, lead poisoning, alcohol excess
Causes of Iron Overload
Primary
•Hereditary haemochromatosis
Secondary
•Transfusional
•Iron loading anaemias
Hereditary Haemochromatosis
Commonest form is due to mutations in HFE gene
•Decreases synthesis of hepcidin
•Increased iron absorption
•Results in gradual iron accumulation with risk of end-organ damage
Hereditary hemochromatosis is a disease in which your body has high levels of iron. That means you have too much iron. It’s often called “iron overload.” Your body can’t get rid of the extra iron, and it ends up damaging your tissues and organs.
normal Hb in children
6 months to 6 years - 110g/l
6+ years - 120g/l
What should we look for in reticulocytosis?
Increased breakdown products like bilirubin may suggest hemolyis is there is a reticuloxytosis.
If bleeding then there is no breakdown products remember.
Splenomegaly due to increased removal of red blood cells may also suggest hemolysis like the increased bilirubin
Reticulocyte responses in anemia
What is the main underlying pathophysiology of ACD?
Inflammation (malignancy, chronic infection and autoimmunity) leading to decreased erythropoetin release from kidneys. Others mechanism exist too such as reduced Erythropoetin, increased hepciden, reduced red cell survival, increased red cell destruction eg by macrophages,
Difference between IDA and ACD in investigations
Very similar results although ferritin is usually low in IDA and normal or increased in ACD. Use ferritin to distinguish the two although remember ACD can also have low ferritin and vice versa sometimes.
MCH
The mean corpuscular hemoglobin, or “mean cell hemoglobin”, is the average mass of hemoglobin per red blood cell in a sample of blood
Low = hypochromic High = hyperchromic
MCHC
MCHC checks the average amount of hemoglobin in a group of red blood cells.
The mean corpuscular hemoglobin concentration is a measure of the concentration of hemoglobin in a given volume of packed red blood cells
RBC
An RBC count is a blood test that measures how many red blood cells (RBCs) you have. RBCs contain hemoglobin, which carries oxygen. How much oxygen your body tissues get depends on how many RBCs you have and how well they work. Blood transports oxygen and nutrients to body tissues and returns waste and carbon dioxide.
HCT blood test
A hematocrit test measures the proportion of red blood cells in your blood.
