10.08.18 Approach to Anemia Flashcards
an automated test to give us information about red cells
Complete Blood Count (CBC)
Is hemoglobin calculated or directly measured?
Directly measured
Volume of red cells per total volume of blood, given as a percentage
Hematocrit
Is hematocrit calculated or directly measured?
Calculated
Direct measurement of the number of red cells
RBC
Direct measurement of red cell volume
MCV
Calculated value, based on Hb and RBC
MCH
Calculate value, based on Hb, MCV, and RBC
MCHC
coefficient of variation of the MCV; how much “spread” there is in the MCVs of all the different red cells in the patient’s body
RDW
How does the distribution of RDW look in iron deficiency
Widened
a decreased hemoglobin/hematocrit below the normal range for gender and age; manifestation of disease not a final diagnosis
Anemia
What does the clinical manifestation of anemia depend on?
- Reduction of oxygen carrying-capacity
- Change in whole blood volume (acute-less, chronic-more)
- Rate of change of Hb
- Cardiopulmonary compensation
- Manifestation of illness that caused anemia
What are most symptoms of acute hemorrhage related to?
Hypovolemia
What are they symptoms of acute hemorrhage
- Hypotension
- Orthostatic changes
- Syncope
- Shock
What are symptoms of tissue hypoxia
- Fatigue
- Shortness of breath
- Cognitive difficulties
- Ischemic pain
How does the body respond to anemia with an increased cardiac output?
Increased heart rate
What reflex does acute blood loss and hypovolemia trigger?
Vasoconstriction
What are chronic changes associated with the body’s response to anemia?
- Kidneys retain salt/water (transfusion require diuretic)
- Increased 2,3DPG leads to right shift in O2 disassociation –> increased O2 delivery to tissues
- Renal mesangial cells sense decreased O2 delivery and increase erythropoietin synthesis
What are the mechanisms of anemia?
- Hemorrhage
- Hemolysis
- Decreased RBC production
How is anemia classified?
- Erythropoietic response (reticulocyte count- hyperproliferative or hypoproliferative)
- RBC size and Hb concentrantion (microcytic/hypochromic, macrocytic, normocytic/normochromic)
On Wright-Giemsa staining these cells are polychromatophilic (grayish blue)
Reticulocyte
Retic count x Hct/ideal Hct x 0.5
Reticulocyte index
Retic (%) x RBC
Absolute reticulocyte count
On supravital staining how are reticulocytes differentiated?
Have RNA “reticulated” remnants
What does retic index <2% or absolute retic count <75000 suggest?
RBC production problem; –> hypoproliferative abnormality
What does retic index >2% or absolute retic count >100000 suggest?
Good marrow response, so anemia is either hemorrhage (blood loss) or hemolysis (RBC destruction)
Tends to reflect a problem with Hb synthesis
iron deficiency, thalassemia, lead poisoning, anemia of chronic disease, and sideroblastic anemias
Microcytic anemia
What lab value classifies microcytic anemia?
low MCV (<80)
Megaloblastic- impairment of DNA synthesis
Non-megaloblastic- variety of other causes
Macrocytic anemia
What lab value classifies macrocytic anemia?
high MCV (>100)
Either the marrow isn’t working well, there is a mixed problem, or there is a very acute problem
Normocytic anemia
What are the 2 approaches to treat anemia?
- Treat the underlying cause
2. Transfusion
How do you decide whether to transfuse?
- How symptomatic is the patient?
- Can we reverse the underlying cause?
- Do we have enough time to treat the underlying cause?
What are the general indications that determine you need a blood transfusion?
- Cardiovascular compromise (CHF, shock, angina)
- Hypoproliferative anemia with no or prolonged recovery
- Anemic patient is going to surgery now- blood loss potential
