Red Blood Cell Disorders Flashcards
Stimuli for EPO release?
Hypoxemia; severe anaemia; high altitude; decreased O2 saturation; left shifted O2 binding curve
Stimuli that repress O2 release?
Increased oxygen content; PV
Extra renal sources of EPO?
RCC and HCC ectopically
How is corrected reticulocyte count measured?
Actual HCT/45* reticulocyte count
> 3% corrected erythropoiesis as an indicator?
Good bone marrow response to anaemia; effective erythropoiesis
Reticulocyte count correction for polychromasia?
Original correction/2
Sites for EMH?
Liver, spleen
Conditions wherein EMH occurs?
Intrinsic bone marrow disease- myelofibrosis
Accelerated erythropoiesis-expansion of bone marrow cavity-sickle cell anaemia, thalassemia beta major
Hematopoiesis sites in fetus?
Yolk sac–> liver–> bone marrow in 5th/6th month of gestation
Parameters decreased in anaemia?
Hb, Hct, RBC concentration
General clinical findings in anaemia?
Pallor of skin, conjunctiva, palmar creases;
Pulmonary valve flow murmur;
Fatigue, dyspnea with exertion;
High output cardiac failure->decreased viscosity
Conditions with increased vs. decreased MCHC?
Decreased->microcytic anaemia
Increased->spherocytosis
Increased RDW?
Iron deficiency anaemia
No citric acid cycle/beta oxidation of fatty acids/production of ketone bodies due to lack of which organelle in mature RBC?
Mitochondria;
Also lack nucleus
Primary pathway of ATP production in RBCs?
Anaerobic glycolysis->lactic acid->to liver converted to glucose via gluconeogenesis
Function of Cori cycle?
Glucose from liver derived from lactic acid produced by RBC–>to RBC–>synthesis of ATP
Function of pentose phosphate pathway by RBCs?
Synthesizes glutathione
GSH converts H2O2 to H2O[prevents destruction] ; neutralises acetaminophen free radicals
Function of methemoglobin reductase pathway in mature RBC?
Heme iron is in ferric form cannot bond to O2;
Reductase system converts it back to ferrous form
Function of luebering-rapoport pathway used by mature RBCs?
Synthesizes 2,3 BPG–> shifts OBC to right–>release of oxygen
Normal lifespan of RBCs?
110-120 days in peripheral blood
How are platelets formed?
Stem cell–>pluripotent cells–>myeloid progenitor–>megakaryocyte–>cytoplasmic budding from megakaryocyte
Which blood components have HLA antigens?
Platelets and RBCs
Ferritin vs. hemosiderin?
Ferritin-soluble iron-binding storage protein
Hemosiderin-insoluble degradation product of ferritin in lysosomes
Synthesis of ferritin?
Bone marrow macrophages/hepatocytes
Decrease in serum ferritin?
Iron deficiency anaemia
Increase in serum ferritin?
ACD- increased IL-6 during inflammation stimulates ferritin production
Iron overload disease
Conditions with decreased serum iron?
Iron deficiency
Conditions with increased serum iron?
Iron overload diseases-sideroblastic anaemia and hemochromatosis
Serum iron vs. serum total iron binding capacity vs. iron saturation?
Serum iron-iron bound to transferrin
TIBC-concentration of transferrin
Iron saturation-% of binding sites on transferrin occupied by iron
Measure iron saturation? And normal values?
= serum iron/TIBC* 100
33%
Types of normal haemoglobin detected on Hb electrophoresis?
HbA=97%
HbA2=2%
HbF=1%
Source of transferrin iron?
Macrophage and duodenum
Why does achlorhydria decrease availability of iron for absorption?
Gastric acid frees elemental iron from heme and non heme products
Absorption of iron from a plant source vs. meat?
Plant source: Fe3+ cannot be absorbed directly; meat: Fe2+ can be absorbed directly into duodenum
Mechanism of regulation of iron absorption?
Iron bound to transferrin–> HFE protein product + transferrin receptors differentiate sensor cells into mature enterocytes
Name the master iron regulatory hormone?
Hepicidin
How does Hepicidin regulate absorption and release of iron?
Increased transferrin bound iron->increased HFE->increased Hepicidin->decreases absorption of iron and release of iron from bone macrophages
Decreased transferrin bound iron-> decreased Hepicidin
Hepicidin is decreased in which conditions?
Normal menstrual cycle
Pregnancy and lactation
Any anaemia
Factor required for production of RBC in BM?
EPO synthesised in renal cortex by interstitial cells of peritubular capillary bed
Most common cause of iron deficiency anaemia in adult male?
PUD–>blood loss
MCC of iron deficiency anaemia in females
Pregnancy and lactation–>increased utilisation