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Name four compensatory mechanisms that help maintain oxygen delivery to the tissues in a patient with anemia
- Increased CO (increased HR and SV)
- Increased extraction ratio
- Right-shift of the O2 dissociation curve due to increased BPG
- Increased plasma volume
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Things to consider in a patient with anemia
- Fhx of hemophilia, G6PD, thalassemia
- Bleeding
- Chronic illness
- Alcoholism (folate and B12 deficiency)
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What effect does one unit of packed RBCs have on Hb and Hct?
- Hb goes up 1 point
- Hct goes up 3 points
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What is the effect of transfusing mismatched blood?
- Intravascular hemolysis--activated complement will punch holes in the RBC membranes
- Patients experience fever, chills, nausea, vomiting, flank pain, and back pain
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What is the MCV cutoff for microcytic anemia?
Under 80
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DD for microcytic anemia
- Fe deficiency
- Thalassemia
- Sideroblastic (impaired protoporphyrin synthesis from lead poisoning, alcohol, or pyridoxine deficiency)
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DD of macrocytic anemia
- B12 or folate deficiency
- Liver disease (impaired plasma membrane protein synthesis results in abnormally shaped RBCs)
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DD of normocytic anemia
- Aplastic anemia
- Bone marrow fibrosis
- Tumor
- Anemia of chronic disease (chronic inflammation, malignancy)
- Renal failure (decreased epo)
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Major diagnosis to rule out in an elderly patient with iron deficient anemia
Colon cancer
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Lab results for Fe deficient anemia
- Low ferritin and serum iron
- High TIBC and transferrin
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Which type of microcytic anemia is characterized by an increased RDW?
Fe deficiency
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Desferroxamine
Fe chelating agent, used to prevent CHF from Fe overload in patients who undergo constant transfusions (e.g. thalassemia patients)
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What test should be performed on a patient with iron deficient anemia who does not respond to iron treatment?
Gel electrophoresis, to rule out a thalassemia
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Causes of sideroblastic anemia
- chloramphenicol
- INH
- alcohol
- lead
- collagen vascular disease
- Malignancy (myelodysplastic syndromes)
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Non-idiopathic causes of aplastic anemia
- Radiation exposure
- Meds (chloramphenicol, carbamazepine)
- Viral infection (Hep B, Hep C, , HPV, EBV, CMV, herpes, HIV)
- Chemicals (benzene, insecticides)
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Which reactions is B12 a cofactor for?
- Conversion of homocysteine to methionine
- Conversion of methylmalonyl CoA to succinyl CoA
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For how long can B12 stores in the liver last?
Up to 3 years
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Where is B12 absorbed?
Terminal ileum
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Causes of B12 deficiency
- Pernicious anemia
- Gastrectomy
- Poor diet
- Crohn's disease, ileal resection
- Diphyllobothrium latum infection
- Bacterial overgrowth
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How can folate deficiency be distinguised from B12 deficiency
- Both are associated with elevated serum homocysteine, but only B12 deficiency is associated wtih elevated methylmalonic acid.
- Also, only B12 deficiency is associated with peripheral neuropathy
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Lab results in hemolytic anemia
- Elevated reticulocytes and LDH
- Low haptoglobins
- Elevated indirect bilirubin
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In what disease may Heinz bodies be seen?
G6PD
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Manifestations of sickle cell anemia
- Blood--chronic hemolytic anemia
- Heart--high output CHF, due to anemia
- CNS--stroke
- GI--gallstones, infarct, abdo pain
- Bones--pain, osteomyelitis, avascular necrosis
- Lungs--infection, acute chest syndrome
- Kidneys--hematuria, papillary necrosis, renal failure
- Eyes--proliferative retinopathy, retinal infarct
- Genitalia--priapism
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Effect of parvovirus B19 infection on a sickle cell anemia patient
Aplastic crisis
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Acute chest syndrome
- Caused by repeated pulmonary infacts
- Presents similarly to pneumonia, with chest pain, respiratory distress, infiltrates, and hypoxia
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Splenic sequestration crisis
- Rapid splenomegaly and hypovolemic shock, caused by pooling of blood in spleen
- Potentially fatal complication of SCD and thalassemia
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Symptoms of hereditary spherocytosis
- Hemolytic anemia
- Jaundice
- Gallstones
- Splenomegaly
- Hemolytic cisis
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Treatment of choice for hereditary spherocytosis
Splenectomy
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Bite cells and Heinz bodies on peripheral blood smear
G6PD
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Warm AIHA
- IgG autoantibodies attack RBC membranes
- RBCs are sequestered in spleen, causing splenomegaly
- May be secondary to lymphoma, leukemia, SLE, and alpha-methyldopa
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Cold AIHA
- IgM autoantibodies attack RBC membranes
- RBCs are sequestered in the liver
- Can be secondary to mycoplasma pneumonia or infectious mono
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Symptoms of PNH
- Chronic intravascular hemolysis
- Hemoglobinuria
- Normochromic, normocytic anemia, due to complement-mediated destruction of RBCs in the spleen
- Pancytopenia
- Venous thrombosis
- Abdo, back, and MSK pain
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Ham's test
- Incubate RBCs in acidic serum, which will activate complement
- Normal RBCs will not be affected, but the RBCs of a PNH patient will lyse
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Heparin-induced thrombocytopenia
- Heparin can induce either platelet aggregation (type I) or antibody-mediated destruction of platelets (type II)
- Administration of heparin will cause clots
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ITP
- Antibody-mediated destruction of platelets
- Patients present withpetechiae and ecchymoses
- NO splenomegaly
- Splenectomy induces remission in 70-80% of cases
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How low does the platelet count need to be for spontaneous bleeding to occur?
Usually below 20,000
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Classic pentad of TTP
- Microangiopathic hemolytic anemia
- Thrombocytopenia
- Acute renal failure
- Fever
- Fluctuating, transient neurological signs
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Treatment for TTP
Plasmapheresis, ASAP
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Most common hereditary bleeding disorder
- vWF, caused by deficient von Willebrand's factor
- Ristocetin-induced platelet aggregation will be low
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Effect of vitamin K deficiency on PT and PTT
- PT is prolonged (factor VII has the shortest half-life of all the clotting factors, so it gets depleted first, when there is not enough vit K)
- PTT is normal (but eventually also gets prolonged, when the other factors are depleted)
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Why does liver disease cause coagulopathy?
- Decreased production of clotting factors
- Cholestasis impairs vitamin K absorption
- Potal hypertension causes hypersplenism, resulting in platelet sequestration
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Factor V Leiden
- Normally, protein C inhibits clotting factors V and VIII, preventing hypercoagulability
- In Factor V Leiden, factor V is resistant to inhibition by protein C, resulting in hypercoagulability
- Associated with hyperhomocysteinemia
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What should be given to a patient on heparin or warfarin with severe bleeding?
FFP
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What is a target INR in most cases?
2-3
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Symptoms of multiple myeloma
- Hypercalcemia
- Renal failure
- Anemia
- Lytic bone lesions, especially in the back, chest, and mandible
- Recurrent infections, due to deficiency in normal Igs
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Monclonal spike (M protein) on gel electrophoresis
Multiple myeloma
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RBCs in rouleaux formation (stacked together)
MM--hyperglobulinemia causes RBCs to stick together
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Diagnosis of Waldenstrom's macroglobulinemia
- IgM over 5 g/dL
- Bence-Jones proteinuria in 10% of cases
- NO lytic bone lesions
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Symptoms of Waldenstrom's macroglobulinemia
- Lymphadenopathy
- Splenomegaly
- Anemia
- Abnormal bleeding
- Hyperviscosity of the blood (can lead to retinal vessel dilation and blindness)
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MGUS
- IgG spike on electrophoresis with Bence-Jones proteinuria
- Under 20% progress to MM
- Don't treat, just follow carefully
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