Erythropoiesis and Anemia Flashcards
Describe the process of erythropoiesis in four steps.
- Myeloid stem cell proliferation and differentiation: stimulated by EPO.
- Further division of cells: Folate (vit B9) and vit B12 required.
- Multi-stage maturation into reticulocytes: Fe required, extrusion of nucleus
- Diapedesis and maturation to RBC
Name the transcriptional regulator responsible for EPO production and release in the kidney.
HIF-1 alpha
Describe the regulation of erythropoiesis in the human body.
Erythropoiesis is controlled by a negative feedback loop. Issues like anemia or low atm PaO2 trigger baroreceptors which detect low arterial PO2. Production and release of HIF-1a is increased, in turn increasing EPO production and release in the kidneys. This stimulates erythropoiesis, increasing mature RBC count and hence increasing oxygen carrying capacity, increasing arterial PO2.
Name some factors affecting RBC loss.
- Usual clearance in spleen (senescent RBCs)
- Blood loss
- Immune destruction
- Genetic defects (eg. Hb)
Name some factors affecting erythropoiesis.
- Hypoxia
- Availability of nutrients (diet)
- Neoplasia
- Blood doping (EPO)
What is mean corpuscular volume (MCV)?
The average volume of each RBC.
What is mean corpuscular Hb (MCH)? How is MCHC calculated?
Mass of Hb per RBC. MCHC is MCH/MCV.
How do clinicians typically classify anemias?
By the MCV (microcytic, normocytic, macrocytic) and MCHC (normochromic, hypochromic, hyperchromic)
26F presents with 1 week of palpitations, has had lifelong heavy periods. The cause of anemia is MOST likely
a. Folate/B12 deficiency
b. Iron deficiency
c. Immune haemolysis
d. Thalassemia
b. Iron deficiency
69F presents with dyspnea on minimal exertion, a/w pallor. She is on B12 replacement for pernicious anemia. FBC shows normocytic hyperchromic RBCs. What is the most likely cause of anemia?
a. Hypothyroidism
b. Haemolysis
c. Iron deficiency
d. Bone marrow dysfunction
b. Haemolysis
