RBC and bleeding disorders - SRS Flashcards
What is the unique ability of hemoglobin?
Bind O2 in high pO2 environment and releases O2 in low pO2 setting.
What regulates RBC progenitor cells?
EPO - a glycoprotein produced and released by peritubular capillary lining cells.
What regulates EPO?
pO2 - amount of oxygen available to the kidney
When Hb levels fall below a certain level the plasma EPO levels increase logarithmically in inverse proportion to the severity of the anemia.
At what level does this occur?
Below 10 grams/dL
What does RDW stand for?
Red cell distribution width
What does hematocrit measure?
Red cell mass expressed as a % of whole blood volume
What is the standard US measurement of anemia?
Hematocrit
What is the european standard for anemia measurement?
Hemoglobin
What is the normal relationship between hematocrit and hemoglobin?
3
Divide hematocrit by 3 to get hemoglobin
multiply hemoglobin by 3 to get hematocrit
What does the RDW provide useful insight for?
Degree of anisocytosis
What are two quick anatomical checks you can make to identify anemia?
Palmar crease
Conjunctiva
What is anemia?
A laboratory finding clinically defined quantitatively as a patient value for hemoglobin or hematocrit which is less than 2.5 percentile value of reference range.
What factors play into the reference ranges upon which anemia is judged?
Age
Sex
measuring technique used by the laboratory
geographic factors including altitude
What are the four factors that clinical findings in RBC function deficiencies are related to?
- Adequate normal hemoglobin vs. impaired hemoglobin
- Acute (rapid) vs. Chronic (slow) loss of RBCs
- Amount or extent of RBC volume loss
- Indirect effects of red cell destruction (iron accumulation in thalassemia or splenic infarction in sickle cell anemia)
Whatever its cause, anemia, when sufficiently severe leads to certain clinical findings. What are some of these?
Pale appearance
Weakness
Malaise
Fatigue
Dyspnea on exertion
What changes can hypoxia cause in the liver, myocardium and kidney?
Fatty change
What is a possible manifestation of myocardial hypoxia?
Angina pectoris, particularly if complicated by pre-existing coronary artery disease.
In the event of acute blood loss and shock, what can develop d/t renal hypoperfusion?
Oliguria and anuria
What are some symptoms of CNS hypoxia?
headache
dimness of vision
faintness
What are the three mechanisms behind anemia?
Blood loss
Increased RBC destruction
Impaired Production
When stressed, by what factor and over what timeline does the bone marrow upregulate red cell production?
4-5 fold within 7 to 10 days
Where does hematopoiesis normally occur?
Red marrow - medullary cavity of flat bones in adults
Where does hematopoiesis occur in exceptional circumstances?
Extramedullary hematopoiesis - Liver, spleen or even lymph nodes
What are the effects of acute blood loss mainly due to?
Loss of intravascular volume
What component of blood is primarily lost in acute blood loss?
plasma for the most part
In acute blood loss a patient may experience hypovolemic shock. What kind of anemia are they likely to have?
What will their EPO levels be?
Normochromic/normocytic anemia
EPO levels normal
What happens to white blood cell count in acute blood loss? Why?
Increases d/t epinephrine and decreased marginalization
What happens to platelet count in acute blood loss?
Increases
In acute blood loss what is the reticulocyte count like?
Normal
Adult humans will experience symptoms with a 10-15% blood volume loss in under an hour. What are some examples of these symptoms?
Rapid pulse
Increased respirations
shortness of breath - with effort especially
Light headed
(all due to defects in vascular volume)
Describe the findings you might expect if a patient has lost more than 20% blood volume in less than one hour?
Vascular shock, postural hypotension
What would you expect in a patient with more than 30% blood volume loss in less than one hour?
Profound shock with confusion, air hunger and hypotension
How long after an acute blood loss does it take for the reticulocyte count to increase?
7 days
What are some common sources of chronic blood loss?
What does this lead to?
GI causes
Gynecological causes
Iron loss
In an older male with anemia, what should you think of as a likely cause?
Colon cancer
When does chronic blood loss induce anemia?
- Rate of loss exceeds the regenerative capacit of the marrow
- Iron reserves are depleted and iron deficiency anemia appears
Chronic anemia does not decrease vascular volume blood pressure suffiently to cause acute symptoms of hypotension. Gradual physiologic accomodation of deficient red cells can occur. What is an example of this?
Increased levels of high energy phosphates (2,3-DPG)
What are some examples of chronic RBC loss/deficiency?
Sickle cell anemia
G6PD deficiency
Thalassemia
Blood loss from large bowel adenocarcinoma
What are four determinants of signs/symptoms in chronic RBC loss/deficiency?
- overall severity of RBC loss
- Rate at which loss occurs
- duration of loss
- associated physical health and age
In chronic blood loss, most adults are asymptomatic until hemoglobin is what level?
under 7
What is going on in this patient?
Why is hematocrit high?
Normocytic anemia
Acute blood loss
High hematocrit because lost more plasma than RBC’s
What is going on with the patient whom this panel is from?
hypochromic Microcytic anemia
Chronic blood loss
