Anemias, Thrombotic Disorders, Bleeding Disorders Flashcards
(86 cards)
What is the definition of anemia?
A reduction in circulating RBC mass.
Name six clinical manifestations of anemia.
- Weakness
- Fatigue
- Dyspnea
- Pale conjunctiva and skin
- Headache, lightheadedness
- Angina, especially when there is pre-existing CAD
What serum Hb value is the cutoff for anemic/not anemic in males and females, respectively?
Anemia is Hb < 13.5g/dL in males and < 12.5g/dL in females
What values correspond to normal MCV?
80-100 fL
What is the differential for macrocytic anemias?
- B12 deficiency
- Folate deficiency
- Orotic aciduria
- Alcoholism
- Liver disease
- Drugs (ex. 5-FU)
Other than measuring serum folate and B12 levels, how can you figure out which is deficient in a person with a macrocytic anemia?
Serum homocysteine and methylmalonic acid levels. If both are elevated, the patient has a B12 deficiency. If only homocysteine is elevated, the patient has a folate deficiency.
What would you see on a blood smear in a patient with megaloblastic anemia?
- Macroovalocytes
2. Hypersegmented neutrophils (>5 lobes)
What is megaloblastic anemia?
A macrocytic anemia caused by either B12 or folate deficiency.
Characterized by macroovalocytes and hypersegmented neutrophils on blood smear, as well as megaloblastic changes in rapidly-dividing cells like GI epithelial cells.
Where along the GI tract is folate absorbed?
Jejunum
In what foods are folate found?
Green vegetables, fruits
Your patient is anemic and a blood smear shows macrocytosis. On physical exam you note glossitis. What diagnosis does this exam finding support?
This supports a B12 or folate deficiency anemia (megaloblastic anemia)
Methotrexate inhibits _________ (an enzyme) and can potentially cause _______ deficiency.
inhibits DHF reductase, can cause folate deficiency
Does the body store much folate? How long does it take to develop a folate deficiency if one suddenly stops eating foods containing folate?
Folate stores are minimal; folate deficiency can develop within months
Describe the process of absorption of B12 in the GI tract.
- B12 binds to haptocorrin/R-binder/transcobalamin, which is made by salivary glands
- In the duodenum, pancreatic enzymes cause dissociation of B12-haptocorrin
- B12 attaches to intrinsic factor
- In the distal ileum, B12-IF binds to cubilin receptors on epithelial cells –> endocytosis
- B12 is released into the blood and binds to transcobalamin/haptocorrin, which is the transport protein for B12 in the blood –> liver (principal storage site for B12)
What foods are B12 found in?
Fish, meat, dairy
Does the body store much B12? How long does it take to develop a B12 deficiency if one suddenly stops eating foods containing B12?
Liver stores a lot of B12 so it takes years to develop B12 deficiency
What is pernicious anemia?
Autoimmune destruction of gastric parietal cells (that make acid and intrinsic factor) –> B12 deficiency
Your anemic patient has lower extremity weakness and hyperreflexive achilles and patellar reflexes. What is possibly going on?
Subacute combined degeneration of the spinal cord from build-up of methylmalonic acid (from B12 deficiency)
Vegans can potentially develop a _____ deficiency due to not ingesting much of it.
B12
In general, anything that disrupts synthesis of ___________ can cause a microcytic anemia.
hemoglobin
What is the differential diagnosis for microcytic anemias?
- Iron deficiency
- Anemia of chronic disease
- Sideroblastic anemia
- Thalassemias
In the early stages of iron deficiency, which lab value would most likely be low: serum iron, TIBC, % saturation, or serum ferritin?
Serum ferritin, because this measures intracellular iron stores, and this is what decreases first
Your anemic patient has mildly low serum iron levels and % iron saturation, but has normal-sized RBCs on blood smear. What is an explanation for this?
Early iron deficiency anemia can cause a normocytic anemia. This is when the bone marrow is simply making fewer RBCs, but they’re normal in morphology.
Other than the six general clinical manifestations of anemia, name two more findings that would be suggestive of iron-deficiency anemia.
- Koilonychia
2. Pica