Microcytic Anemia 9/27 Flashcards
what can cause falsely abnormal MCV? (5)
- cold agglutins
- hyperglycemia
- reticulocytosis
- leukocytosis
- acute hemolysis
Corrected Reticulocyte count
Absolute Reticulocyte count x (pt’s Hgb/normal Hgb)
Hypoproliferation: <2%
To correct for shift Reticulocytes (some released early due to low Hgb ~12), calculate the Reticulocyte production index:
(Reticulocyte %/ Reticulocyte maturation time) x (Hgb/15)
Reticulocyte maturation time for: Hgb of 15? Hgb of 12? Hgb of 8? Hgb of 5?
15: 1 day
12: 1.5 days
8: 2 days
5: 2.5 days
What does RPI less than 2 indicate?
Patients bone marrow is not making enough Reticulocytes
RPI over 3 indicates the marrow is responding appropriately to anemia.
What accounts for decreased red cell production? (Reticulocytopenia)
- Hgb synthesis lesion: iron deficiency, thalassemia, anemia of chronic disease
- DNA synthesis lesion: megaloblastic anemia
- DNA synth inhibitor drugs
- Hematopoetic stem cell lesion: leukemia
- Bone marrow infiltration: lymphoma, sarcoidosis, etc
What accounts for increased RBC destruction/loss? (Reticulocytosis)
- Acute blood loss
- Intrinsic Hemolysis: membrane lesion, Hgb lesion, glycolysis abnormality, oxidation lesion (G6PD deficiency)
- Extrinsic hemolysis: immune, angiopathic.
- Valve dysfunction
- Infection
- Hypersplenism
Normal RDW, low MCV
Thalassemia
Chronic disease
Normal RDW, high MCV
Aplastic anemia
Myelodysplasia
Alcohol
Normal RDW and normal MCV
Chronic disease (90%)
Hereditary spherocytosis
Acute bleed
Cirrhosis
Uremia
High RDW and low MCV
Iron deficiency
S-thalassemia
RBC fragmentation
High RDW and high MCV
B12/folate
Autoimmune hemolysis
Cold agglutins
High RDW and normal MCV
Early factor deficiency
SS disease
SC disease
Sideroblastic anemia
Myelofibrosis
For microcytic anemia, MCV IS LOW. What do RDW values tell us?
High RDW: iron deficiency, S-thalassemia, RBC fragmentation
Low RDW: thalassemia, chronic disease
What is the differential diagnosis of microcytosis (low MCV)?
-iron deficiency
-thalassemia
•B: elevated Hgb A2 or F
-anemia of chronic disease
-sideroblastic anemia (rare)
-lead poisoning (rare)
-zinc deficiency
Cause of microcytosis?
Reduced Hgb synthesis
Either iron defects OR hemoglobinopathies
How to test for iron deficiency? (4)
- Iron
- TIBC
- Iron or transferrin saturation
- Ferritin
What molecule transports iron after absorption?
Transferrin
What molecule stores iron in the liver and heart?
Ferritin (10-20% of absorbed iron)
Common reasons for iron loss?
Ulcers GI bleeds Liver disease IBS Hemorrhoids Colon cancer
How much iron is lost in females per day?
1-3 mg.
Pregnancy: 6 mg/day
How can exercise result in iron deficiency?
- GI tract blood loss
- Exercise-induced hemolysis
- Increased levels of hepcidin
Also… Bariatric surgery.
How do you approach iron deficiency anemia?
In older makes, LOOK FOR GI SOURCE
how else can one lose blood? Menstruation, post surgery.
FIND BLEED; STOP BLEEDING
What is the go-to iron therapy treatment and dosage?
Ferrous sulfate: 325 PO per day.
How to treat iron deficiency If ferrous sulfate is not tolerated?
Ferrous gluconate
Iron drops
Lower dose + vitamin C/ cranberry juice
If unresponsive to oral iron therapy, utilize parenternal iron therapy. What drugs are used? (5)
- Iron dextran: start w/ 25 mg to test for adverse rxn, then give 975 mg.
- Ferric Gluconate: 125mg/hour x 7 sessions
- Iron sucrose
- Ferumoxytol: 510mg over 17 seconds. Repeat in a week
- Ferric carboxymaltose: 750mg. Repeat in one week
What is hepcidin and where is it synthesized?
Synth in LIVER.
prevents parenchyma iron overload
Reduces quantity of circulating iron by preventing its exit from cells (erythrocytes & macrophages)
what molecule does hepcidin work on and how?
Hepcidin binds to ferroportin* and induces its internalization and degradation. Keeps iron inside RBCs.
*ferroportin is a transmembrane protein that transports iron from inside the cell to the outside -> bloodstream.
What happens with low or no hepcidin?
Parenchymal iron overload
Iron testing: iron/TIBC/ferritin in iron deficiency?
Serum iron: LOW
TIBC: high
ferretin: LOW
Iron testing: iron/TIBC/ferritin in anemia of chronic disease?
Serum iron: LOW
TIBC: LOW
Ferretin: high
When do you get Hgb electrophoresis in evaluating anemia? (3)
Family history of hemoglobinopathies/ race
Microcytosis w no or mild anemia
Iron studies not indicative of another process
What is the cause of sideroblastic anemia?
Elevated iron
Usually acquired disorder: MDS, alcohol, Meds
Can be X-linked
Multiple small blue/black spots on RBC indicate basophilic stippling. What does this mean?
Pb (LEAD) TOXICITY
or thalassemia
What are the clinical manifestations of lead poisoning?
Hypochromic microcytosic anemia
Lead inhibits heme production by preventing iron incorporation into protoporphyrin ring
Symptoms: anorexia, abdominal pain, irrationality. RADIAL PALSY
