Approach to the Adult Patient with Anemia Flashcards
What is erythropoiesis?
The production of RBC
What does EPO bind to?
Marrow erythroid precursors (proerythroblasts)
What does EPO due?
Induces RBC maturation
What vitamins assist in RBC proliferation?
Folate and B12
What would we expect to see in a folate and/or B12 deficiency?
Large RBCs
What vitamin assists in the accumulation of hemoglobin?
Iron
What would be expect to see in an iron deficiency?
Small RBC
What does a reticulocyte look like?
Larger than mature RBC
Not biconcave
Bluer
Has RNA
What conditions do you need for erythropoiesis?
EPO
Normal marrow function
Hgb accumulation
What is anemia?
A reduction in one or more of the major red blood cell measurements (Hgb, Hct, or RBC)
What is the Kinetic approach to anemia?
Address the mechanism responsible for the fall in Hgb concentration
What is the Morphologic approach to anemia?
Categorize the anemia based on RBC characteristics and the reticulocyte response
What can cause anemia (3 broad categories)?
Decreased RBC production
Increased RBC destruction
Blood loss
How much RBCs are replaced in a day under steady state conditions?
1% of red cell mass
What can cause decreased RBC production (5)?
- Lack of nutrients
- Bone marrow disorders
- Bone marrow suppresion
- Low levels of trophic hormones (EPO, thyroid, androgens)
- Acute/chronic inflammation
What can cause RBC destruction (3)?
- Inherited hemolytic anemias
- Acquired hemolytic anemias
- Hypersplenism
What is the most common cause of anemia?
Blood loss
What can cause blood loss (4)?
- Gross blood loss
- Occult blood loss
- Iatrogenic blood loss
- Underappreciated menstrual blood loss
How does iron deficiency worsen anemia?
When RBCs are lost due to persistent bleeding the iron is lost with it instead of being reused after RBC destruction. Then you have worsened anemia because you inhibit RBC synthesis.
What is the reticulocyte count for a hemorrhage?
High
What is the reticulocyte count for decreased RBC production?
Low
What is the reticulocyte count for increased RBC destruction?
High
What conditions might cause you to NOT see a high reticulocyte count (3)?
EPO deficiency
Damaged bone marrow
Otherwise you don’t need more RBC and don’t have anemia
What does a high MCV let us determine about RBC?
Macrocytic anemia
Reticulocytes are larger than RBC so we know a high MCV means we have reticulocytosis or high reticulocytes
What lab values are used to assess anemia in the morphological approach?
MCV, MCH, MCHC
Size
Color
Concentration of Hgb
What are common causes of macrocytic anemia?
- Nutrient deficiency - folate and B12
- Drugs
- Abnormal RBC maturation
- Alcohol and liver disease
What are common causes of microcytic anemia?
Iron deficiency!!!!
And sometimes alpha or beta thalassemia minor but those are diagnosed at a young age
What are common causes of normocytic anemia?
Think no nutrient deficiency!
CKD, chronic disease/inflammation, mild iatrogenic
What is the overarching cause of anemia symptoms?
Lack of oxygen to tissues due to low Hgb
How does the body compensate for anemia?
- Increase O2 extraction from 25% to 60%
- Increase SV and HR
What are common symptoms of anemia?
Fatigue
Exertional tachycardia and DOE
Tachycardia
SOB
Palp
Audible pulsations
Bounding pulses
Pallor
Blood loss anemia:
Cramps
Dizziness
Lethargy
Hypotension
Is anemia ever normal?
No
What to ask yourself of a patient with anemia?
- Bleeding?
- RBC destruction?
- Bone marrow suppression?
- Nutrient deficient?
What are sx and PMHx that are associated with anemia?
- Melena
- Hematochezia
- Menorrhagia
- CKD
- RA
- CHF
- Ethnicity and fam history
- EtOH
- ASA NSAIDs anticoagulants
What are PE findings c/w anemia?
Pallor, jaundice, petechiae, bruising
Pale conjunctica, scleral icterus
LAD
Hepatoslenomegaly
Bony tend esp sternum and anterior tibia
Occult blood in stool
What are the labs you should order?
CBC with diff and platelets
Which CBC lab values will be effected by volume status?
Hgb, Hct, RBC (all concentrations)
If you give a patient IV fluids, what will happen to their RBC and H&H?
Lower
If a patient is dehydrated, what will happen to their RBC and H&H?
Increase (known as hemoconcentration)
Why might reticulocyte count be inaccurate in a patient with anemia?
If there are low overall RBC the Reticulocyte count could be falsely elevated because it is a percentage. There could be a normal overall number of reticulocytes.
What does an elevated reticulocyte count indicate?
Hemolysis
If you suspect hemolysis, what should you order?
- reticulocyte count (high)
- Serum lactate dehydrogenase (high)
- Indirect bilirubin (unconjucated) (high)
- Serum haptoglobin (low)
- Coombs test, direct (for autoimmune screening, looks for antibodies on RBCs)
Where is iron found in the body?
- In Hgb 65%
- Stored as ferritin or hmosiderin (spleen, bone marrow, liver) 30%
- In myoglobin 4%
- In cells <1%
- Bound to transferrin 0.1%
What does a serum iron measure?
Iron bound to transferrin in the blood
What does the transferrin saturation measure?
How much of the transferrin is bound by iron
What is total iron binding capacity (TIBC)?
The blood’s capacity to find iron with transferrin, indirectly measures transferrin
What is the most reliable measure of total body iron status?
Ferritin aka the iron storage (that is if you cant use the bone marrow)
What labs should you order to evaluate macrocytic anemia?
Reticulocyte count
Folate
B12
Why might folate levels be elevated in B12 deficiency?
B12 moves folate out of serum to cells
What should you order to evaluate normocytic anemia?
Just a reticulocyte and then look at etiology
