Module 1: Chronic Hemolytic Anemia (Hereditary Spherocytosis) Flashcards
What is Anemia and how is it determined?
Reduction (below normal limits) of total circulating red cell mass
–determined from Hb concentration or packed cell volume/hematocrit
Explain MCV,MCH,MCHC and RDW
MCV: average volume of RBC
MCH: average content of Hb per RBC
MCHC: average concentration of Hb in a given volume of packed RBCs
RDW: coefficient of variation of RBC volume/size
Clinically how does anemia present?
Asymptomatic, when mild
- -symptomatic: related to poor O2 supply to tissues: weakness, easy fatigability, headaches, fainting, SOB on exertion
- -increase pulse, resp rate and SV (Eventually heart failure)
- -pallor, nail changes in severe cases
Anemia classification is based on what three things?
- Degree of hemoglobinization (color)(pinkness): mature RBCs are either normochromatic or hypochromatic
- Cell size: RBCs are macrocytic, normocytic or microcytic
- Cell shape: spherocytes, sickled, etc.
Again what is microcytic and macrocytic?
Microcytic (low MCV): small red blood cells (nucleus of lymphocytes is much bigger)
Macrocytic (high MCV): large red blood cells (nucleus of lymphocytes is much smaller)
–remember that MCV is the average volume of RBC
What are the two underlying mechanisms for anemia?
- Accelerated blood loss/destruction: peripheral
- -blood loss: acute hemorrhage or chronic blood loss
- -increased rate of destruction= hemolytic anemia - Impaired RBC production: bone marrow
The first type of anemia we will discuss will be hemolytic anemia, which is again an increase in the rate of destruction of RBC, what are common features?
Shortened RBC life span
increase erythropoietin and erythropoiesis
accumulation of Hb breakdown products
Erythroid Hyperplasia (increased intramedullary erythroposis): bone marrow is trying to compensate for increased RBCs
Reticulocytosis: increased reticulocyte count
Retention of products of RBC destruction (bilirubin and iron)
Increased rate of RBC destruction
What are the different classifications of hemolytic anemia?
Site: intravascular (inside blood vessel) vs. extravascular (outside blood vessel) —–spleen
Cause: Intrinsic or extrinsic (to RBCs)
What are the intrinsic anemias?
Hereditary
Hereditary Spherocytosis: membrane abnormalities
G6PD: enzyme deficiencies
Sickle Cell and Thalassemaia: Hb synthesis
Acquired
Paroxysmal Nocturnal Hemoglobinuria: membrane defect
What are the extrinsic anemias?
Acquired
Ab mediated
Non-immune: damaged endothelium damages RBCs
sequestration :due to hypersplenism
What is intravascular hemolysis due to?
- Mechanical Injury to RBCs due to: defective cardiac valve or microvascular thrombi
- Complement fixation of Ab-coated RBCs
- Infections: intracellular parasites, production of toxins= cell lysis
- -Hb products in the blood and urine
- -direct damage to the RBC membrane right in the intravascular space
What products do you find in the blood and urine in intravascular hemolysis?
- Decreased Haptoglobin
- Increased LDH (non specific marker of cell lysis)
- Increased Hemoglobinuria (urobilinogen is spilling into the urine)
- Increased Unconjugated bilirubin
What is Extravascular hemolysis?
Occurs in the actual spleen
- -RBCs rendered less deformable (spherocytosis, sickle cell)
- -RBCs rendered foreign (by immune mechanism)
- -hemolysis in extravascular spleen is most causes of hemolytic anemia
What are the lab values or extravascular hemolysis?
- Increased LDH
- Increased Unconjugated Bilirubin (jaundice)
- Decreased haptoglobin
There are 4 different types of Hemolytic Anemia that will be discussed in this course. The rest of these cards will be explaining these: The first is Hereditary spherocytosis, what type of anemia and hemolysis is this?
Normocytic anemia with predominant extravascular hemolysis (remember this occurs in the actual spleen but outside the blood vessel)
–inherited hemolytic anemia
Is hereditary spherocytosis, autosomal dominant or recessive?
More common is AD but can be AR and this is more severe
–northern europeans (Swedish)