Heme/Onc Pathophys Flashcards
RBC lifespan
120 days
what happens to RBC at end of life?
phagocytized in reticuloendothelial system
what does RBC destruction stimulate?
erythropoiesis
role of hemoglobin
transport vehicle for oxygen
definition of anemia
reduction in the volume (hematocrit) of or concentration (hemoglobin) of RBCs when compared to similar values from a reference population
what is hgb
expression of amount
what is hct
expression of volume
describe the mechanisms of anemia
5 general
- RBCs destroyed early
- ineffective erythropoiesis
- insufficient erythropoiesis
- blood loss
- hemolysis
4 things required for RBC production
- iron
- B12
- folic acid
- erythropoietin
what is the role of erythropoietin?
stimulates RBC production when O2 is low
compensatory response to severe bleeding (acute onset w/ massive volume loss)
- immediate: peripheral vasoconstriction and central vasodilation
- w/ time: systemic small vessel vasodilation
components of systemic small vessel vasodilation
- increased blood flow to increase tissue oxygenation
- decreased systemic vascular resistance
- increase cardiac output, tachycardia, tachypnea
what way will Hgb-O2 dissociation curve shift w/ anemia? why?
- right shift
- enhances O2 release to tissues
2 other compensatory responses for anemia
- increase in plasma volume to enhance tissue perfusion
- stimulation of EPO production
causes of left shift on hgb-O2 curve
6
- low temp
- high pH
- low 2, 3-BPG
- fetal Hb
- methemoglobinemia
- carboxygemoglobinemia
describe the implications of a left shift on hgb-O2 curve
- increased oxygen affinity (stays w/ hgb)
- reduced oxygen delivery to tissues
causes of right shift on hgb-O2 curve
4
- low pH
- increased CO2
- high temp
- high 2,3-BPG
describe the implications of a right shift on hgb-O2 curve
- reduced oxygen affinity (leaves hgb easier)
- increased oxygen delivery to tissues
causes of decreased RBC production
5 primary causes
- marrow failure/suppression (decreased raw materials, RBC defects, blood cancers, chemo)
- renal failure (decreased EPO)
- lack of nutrients (iron, B12, folic acid)
- low levels of hormones which stimulate RBC production
- chronic disease/inflammation
differentials for anemia due to accelerated loss of RBCs
4 categories
- inherited hemolytic anemias (sickle cell, thalassemia major)
- acquired hemolytic anemias (autoimmuno, TTP/HUS, malaria)
- G6PD deficiency
- hereditary spherocytosis
screening recs
- infants at 9-12 mo
- pregnant women
key hx components
8
- hx of medical condition known to result in anemia
- onset of anemia
- ethnicity/country of origin
- mediations/supplements
- use of alcohol, aspirin, NSAIDs
- hx of blood transfusions
- exposure to toxic chemicals
- hx of liver disease
key sx of anemia
10
- DOE, SOB
- fatigue
- weakness
- palpitations
- dizziness
- poor concentration
- HA
- angina/a. fib
- neuropathy
- pica (craving ice)
key signs of anemia
8
- orthostatic vital signs
- jaundice
- lymphadenopathy
- bony tenderness
- petechiae
- pallor
- tachycardic
- melena (FOBT testing)