Hematology and Oncology Flashcards
Definition of Anemia
Reduction in Hct or Hgb
Compensatory Mechanisms to Maintain O2 Delivery to Tissue
- ) Increased SV or CO/HR
- ) Increased Extraction Ratio
- ) Rightward shift on oxyhemoglobin curve
- ) Expansion of Plasma Volume
When is a transfusion needed?
- Hgb <7
2. Patient requires increased O2 carrying capacity (CAD or cardiopulmonary disease)
Symptoms of anemia (specific and nonspecific)
Nonspecific: fatigue, poor concentration, diarrhea, headache, nausea, vague abdominal discomfort, hypotension, tachycardia, pallor (best if seen in conjunctiva)
Specific: jaundice if hemolytic anemia, blood in stool if GI bleed
1 unit of PRBCs increases Hgb by?
1 point of Hgb, 3 points of Hct
If H/H reveals anemia, what is the next best step?
Get a retic count and MCV
Effective Erythropoeisis Depends on:
- ) Adequate raw materials: folate, B12, Iron
- ) Absence of intrinsic bone marrow disease
- ) Adequate EPO release from kidney
- ) Survival of reticulocytes (no destruction prior to leaving the bone marrow).
What does it mean if retic count is >2%
excessive RBC production or blood loss. The bone marrow is responding adequately to the cause of anemia.
What does it mean if retic count is <2%
Inadequate RBC production by bone marrow
Why do you mix PRBCs with Normal Saline and not Lactated Ringers?
Because the calcium in LR causes coagulation within the IV lines.
What should you check after a transfusion of PRBCs is completed?
CBC
What does FFP contain?
All of the clotting factors and no WBCs/RBCs.
Why do you give FFP?
Coagulopathy, high PT/PTT, deficiency of clotting factors, liver failure (since vitamin K won’t work)
What should you check after infusion of FFP?
PT/PTT
What does cryoprecipitate contain
Factor VIII and Fibrinogen
Why do you give cryoprecipitate?
Hemophilia A, von Willebrand Disease, or DIC (due to decreased fibrinogen)
How much will 1 unit of platelets raise the platelet count by?
10,000
Is acute hemolytic reaction intravascular or extravascular hemolysis?
Intravascular: Caused by ABO mismatched blood transfused into the patient. IgM antibodies attach to the infused RBCs, activate a complement pathway, and produce a massive intravascular hemolysis as C9 punches holes in the RBC membrane.
Symptoms of Acute Hemolytic Reaction
N/V, fever, chills, pain in flank/back, chest pain, dyspnea
Complications of Acute Hemolytic Reaction
DIC, renal failure w/ hemoglobinuria, hypovolemic shock with hypotension and tachycardia
How do you treat/manage Acute Hemolytic Reaction?
- Stop the transfusion!!!
- Aggressive fluid replacement to prevent renal failure and shock
- Epinephrine for anaphylaxis
- Dopamine/NE as needed for pressors/to maintain BP
Is delayed hemolytic transfusion reaction intravascular or extravascular?
Extravascular.
What causes a delayed hemolytic transfusion reaction
Can occur 3-4 days after transfusion. It occurs when one of the minor RBC antigens is found in the transfusion. Reexposure of memory B cells to the antigen on RBCs after prior exposure results in the synthesis of IgG anti-Kell (for ex) antibodies. These antibodies coat the antigen positive RBC donor cells which will be removed extravascularly by macrophages in the liver and bone marrow.
Symptoms of delayed hemolytic transfusion reaction
fever, jaundice anemia
How do you treat/manage delayed hemolytic transfusion reaction?
Don’t do anything. The prognosis is good and is usually self limited.
Definition of Microcytic Anemia
MCV <80
What is in the differential diagnosis of a microcytic anemia?
- ) Iron deficiency anemia
- ) Anemia of Chronic Disease
- ) Thalassemias
- ) Ring Sideroblastic Anemias (lead poisoning, pyridoxine deficiency, toxic effects of alcohol)
Definition of Macrocytic Anemia
MCV >100
What is in the differential diagnosis of macrocytic anemia?
- ) Nuclear defect: Folate or B12 deficiency
- ) Liver disease
- ) Stimulated erythropoiesis
How does liver disease lead to a macrocytic anemia?
MCV can get up to 115! This is due to altered metabolism of plasma lipoproteins into their membranes altering the shape of RBCs and therefore their volume.
What is in the differential diagnosis of a normocytic anemia?
- ) Aplastic anemia
- ) Bone marrow fibrosis
- ) tumor
- ) Anemia of Chronic Disease
- ) Renal Failure 2/2 to decreased EPO production
If the Retic index is >2% what should you do?
- ) Consider blood loss and look for the source.
2. ) Consider hemolysis and check: LDH, haptoglobin, bilirubin levels
What are the 2 most common causes of iron deficiency anemia worldwide?
- ) Chronic blood loss
2. ) Increased iron requirements/dietary deficiency
What are the 2 most common causes of chronic blood loss leading to anemia?
- ) Menstrual blood loss
2. ) GI bleeding
What populations require increased iron or are at risk of dietary deficiency of iron?
- ) Infants and toddlers, particularly those who are on human breast milk
- ) Teenagers, especially menstruating girls
- ) Pregnant women
Diagnostic values of the following for iron deficiency anemia: Ferritin TIBC/Transferrin levels TIBC Saturation Serum Iron Peripheral blood smear
Ferritin: decreased TIBC/Transferrin levels: increased TIBC Saturation: decreased Serum Iron: decreased Peripheral blood smear: microcytic hypochromic RBCs
Treatment of Iron Deficiency Anemia:
- ) In menstruating females try a trial of oral ferrous sulfate.
- ) in men and postmenopausal women attempt to determine the source of bleeding
Describe the pathophysiology of beta-thalassemia
beta chain production is deficient but alpha chain production is normal. Excess alpha chains bind to and damage the RBC membrane.
Describe the pathophysiology of alpha thalassemia
There is a decrease in the alpha chain production. The excess beta chains form tetramers which are abnormal hemoglobins.
What is a complication of the treatment of thalassemia major?
Iron overload because these patients are often transfusion dependent
If iron deficiency anemia is suspected but it does not respond to oral iron therapy, what is the next best step?
obtain a hemoglobin electrophoresis to rule out alpha or beta thalassemia
What are the clinical features of thalassemia major/Cooley anemia/homozygous beta-chain thalassemia?
- Severe anemia that is microcytic and hypochromic
- Massive hepatosplenomegaly
- Expansion of the marrow space which can cause distortion of bones
- Growth retardation and FTT
- Progressive CHF if left untreated
- Crew cut appearance of skull on XR.
What is seen on the hemoglobin electrophoresis of a patient with thalassemia major? Peripheral blood smear?
- Elevated HbF and HbA2.
2. Hypochromic microcytic cells; target cells
What are the clinical features of thalassemia minor/heterozygous beta-chain thalassemia?
these patients are usually asymptomatic and usually require no treatment.
What is the genotype of a silent carrier of alpha thalassemia?
These patients have a mutation/deletion of only ONE of the alpha-locus.
They are asymptomatic with a normal H/H and require no treatment.
What is the genotype of alpha-thalassemia trait or alpha thalassemia minor?
These patients have a mutation/deletion of TWO of the alpha locus.
They may have a microcytic hypochromic anemia and usually require no treatment. Common in AAs.
What is the genotype of HbH disease?
This is hemoglobin Barts disease. These patients have mutation/deletion of THREE of the alpha loci.
Hemoglobin electrophoresis will show HbH. Treatment is transfusion, sometimes splenectomy is helpful.
What is the genotype of alpha thalassemia major?
This is a mutation/deletion of all FOUR alpha loci. These patients often have hydrops fetalis and die shortly after birth.
What is the most common type of thalassemia?
Thalassemia minor. Beta-thalassemia minor is more common than alpha-thalassemia minor.
What are the lab results of the following for sideroblastic anemia? Ferritin TIBC/Transferrin TIBC Saturation Serum iron
Ferritin: increased
TIBC/Transferrin: normal TIBC
TIBC Saturation: normal/elevated
Serum iron: increased
Ringed sideroblasts in bone marrow
What is the treatment for sideroblastic anemia
- ) Remove the offending agent
2. ) Consider pyridoxine
What are some of the acquired causes of sideroblastic anemia
- ) Drugs: chloramphenicol, INH, alcohol
- ) Lead exposure
- ) Collagen vascular disease
- ) Neoplastic disease: myelodysplastic syndromes.
What is the pathophysiology of sideroblastic anemia?
It is caused by an abnormality of iron metabolism in RBCs.
Why does chronic inflammation lead to anemia?
It is thought that inflammatory cytokines have a suppressive effect on erythropoiesis
What are the lab results of the following for anemia of chronic disease? Ferritin TIBC/Transferrin TIBC Saturation Serum iron
Ferritin: increased TIBC/Transferrin: low TIBC Saturation: high Serum iron: low Normocytic and normochromic
What are the causes of aplastic anemia?
- ) Idiopathic
- ) Viral: parvovirus, Hep C, Hep B, EBV, CMV, Herpes zoster varicella, HIV.
- ) Malignancy
- ) Radiation exposure
- ) Medications: chloramphenicol, sulfonamides, gold, carbamazepine
- ) Chemicals: benzene, insecticides.
What are the clinical features of aplastic anemia?
- ) fatigue and dyspnea due to anemia
- ) Increased risk of infection due to neutropenia
- ) Petechiae, bruising due to thrombocytopenia
What is a feared complication of aplastic anemia?
Transformation into an acute leukemia
How do you make the diagnosis of aplastic anemia?
- ) The peripheral smear will show a normochromic normocytic anemia.
- ) Bone marrow biopsy will show hypocellular marrow and the absence of progenitor cells for all 3 cell lines.
What are the two reactions in which B12 is an important cofactor?
- ) Homocysteine to Methionine
2. ) Methylmalonyl CoA to Succinyl CoA.
Where is vitamin B12 absorbed?
In the terminal ileum while bound to intrinsic factor (produced by gastric parietal cells).
What are the causes of vitamin B12 deficiency?
- ) Pernicious anemia
- ) Gastrectomy
- ) Poor diet (vegetarianism, alcoholism)
- ) Crohn’s Disease, Ileal resection
- ) Organisms competingg for B12–> Diphyllobothrium latum (fish tapeworm), blind loop syndrome (bacterial overgrowth).
Define pernicious anemia
An autoimmune condition resulting in inadequate production of intrinsic factor by the gastric parietal cells. This leads to impaired absorption of vitamin B12 in the terminal ileum.
Clinical features of vitamin B12 deficiency:
- Anemia
- Sore tongue
- Neuropathy
What are the neurologic manifestations of vitamin B12 deficiency?
- ) Neuropathy secondary to demyelination of the posterior columns, the lateral CST< and the spinocerebellar tracts
- ) Impaired proprioception
- ) Ataxia
- ) UMN signs, hyperreflexia, spasticity, weakness, upgoing Babinski.
- ) Urinary and fecal incontinence
- ) Dementia
What are 2 things you would see on a peripheral smear to diagnose B12 deficiency?
- ) Macrocytic RBCs (MCV >100)
2. ) Hypersegmented neutrophils
What two values in the serum will be elevated with vitamin B12 deficiency?
- ) Elevated methylmalonic acid
2. ) Elevated homocysteine levels
What is the treatment for vitamin B12 deficiency?
Cyanocobalamin (vitamin b12) IM once per month.
How long does it take to become deficiency in folate? in B12?
Folate–> 3 months
B12–> 3+ years
What are the causes of folate deficiency?
- ) Inadequate dietary intake “tea and toast” diet
- ) Alcoholism
- ) Long term use of antibiotics
- ) Increased demand
- ) Pregnancy
- ) hemolysis
- ) Use of folate antagonists like methotrexate
- ) Anticonvulsant medications (phenytoin)
- ) Hemodialysis
What is the treatment for folate deficiency?
Daily oral folic acid replacement
What are the serum levels of methylmalonic acid and homocysteine in folate deficiency compared to B12 deficiency.
In folate deficiency, serum levels of homocysteine are high but methylmalonic acid levels are normal. Therefore if both are elevated, it must be a vitamin B12 deficiency.
Hemolysis due to external RBC defects can be caused by?
- ) Immune hemolysis
- ) Mechanical hemolysis (prosthetic heart valves, MAH)
- ) Medications, burns, toxins
Most of these are ACQUIRED cases of hemolysis.
Hemolysis due to internal RBC defects can be caused by?
- ) Hemoglobin abnormality like sickle cell dz, HbC dz, thalassemia
- ) Membrane defects like hereditary spherocytosis, PNH
- ) Enzyme defects like G6PD deficiency, pyruvate kinase deficiency
Where does intravascular hemolysis occur? extravascular?
Intravascular–> within the circulation
Extravascular–> within the reticuloendothelial circulation, the spleen.
What are the clinical features of hemolytic anemias?
- Signs and symptoms of anemia
- Jaundice
- Signs and symptoms of whatever underlying disease they have
- Dark color of urine (due to hemoglobinuria)
- Hepatosplenomegaly, cholelithiasis, lymphadenopathy
Does hemoglobinuria indicate intra or extravascular hemolysis?
Intravascular hemolysis.
What are the typical lab values/findings seen in hemolytic anemia?
- ) Anemia
- ) Elevated retic count
- ) Elevated LDH
- ) Decreased haptoglobin
- ) Decreased hemoglobin and hematocrit
- ) Elevated indirect bilirubin
G6PD Deficiency peripheral smear
Heinz Bodies
Extravascular hemolysis on peripheral smear
Helmet cells or spherocytes
Intravascular hemolysis on peripheral smear
Schistocytes
Why is haptoglobin low in hemolytic anemias?
Haptoglobin binds to hemoglobin so when haptoglobin is low it indicates that hemoglobin has been destroyed.
What is the specific mutation that causes sickle cell disease?
Uncharged valine is substituted for a negatively charged glutamic acid at the sixth position of the beta-chain.
What type of conditions cause sickling?
Decreased oxygen conditions: acidosis, hypoxia, changes in temperature, dehydration, and infection.
Patients with sickle cell trait often have this unique finding in their urine:
Isothenuria. This is the inability to concentrate or dilute the urine. Patients have a constant osmolality on urine testing.
What causes hand foot syndrome/dactylitis in SCD?
Avascular necrosis of the metacarpal and metatarsal bones. This is often the first manifestation of sickle cell disease. Causes painful swelling of the dorsa of the hands and feet seen in infancy and early childhood.
What are 3 medical interventions that can be done to prevent complications of sickle cell disease.
- ) Early vaccination against S. Pneumo, H. Flu, and N. Mening
- ) Prophylactic PCN from 4 mos to 6 yrs old.
- ) Folate supplementation due to chronic hemolysis
Hereditary Spherocytosis:
- Inheritance pattern
- Pathology
- Autosomal dominant
- Defect in the gene coding for spectrin and other RBC proteins. There is a loss in RBC surface area without a reduction in RBC volume, necessitating a spherical shape. The spherical RBCs become trapped and destroyed in the spleen by macrophages–> extravascular hemolysis.
What are the causes of spherocytosis? There are 5.
- Hereditary spherocytosis
- G6PD deficiency
- Hyperthermia
- ABO incompatibility (but not Rh incompatibility)
- Autoimmune hemolytic anemia
What are the clinical features of hereditary spherocytosis?
- Hemolytic anemia
- Jaundice
- Splenomegaly
- Gallstones
- Occasional hemolytic crises
What is the treatment of choice for hereditary spherocytosis?
Splenectomy
Describe the osmotic fragility test as it relates to hereditary spherocytosis.
The osmotic fragility test tests the ability of RBCs to swell in a graded series of hypotonic solutions. Because of their shape, spherocytes tolerate less swelling before they rupture; thus they are osmotically fragile. The RBCs undergo lysis at a higher/earlier oncotic pressure.
G6PD Deficiency:
- Inheritance pattern
- Pathology
- X-linked recessive
2. defect in glucose-6-phosphate dehydrogenase that results in hemolytic episodes caused by precipitating factors.
Known precipitants to G6PD:
- fava beans
- sulfonamides
- nitrofurantoin
- primaquine (anti-malarials)
- dimercaprol
- infection
What are the clinical features of G6PD deficiency?
- Episodic hemolysis
- Jaundice and dark urine on examination
What does a peripheral blood smear show in a patient with G6PD?
- Bite Cells
- Heinz Bodies
What are bite cells
Bite Cells are RBCs after the removal of Heinz bodies by phagocytes like splenic macrophages.
What are Heinz bodies?
Heinz bodies are abnormal hemoglobin precipitates within the RBCs.
How do you treat G6PD?
- Transfuse as necessary
- Avoid precipitants of hemolysis
- Maintain hydration
Define the pathology of AIHA (autoimmune hemolytic anemia).
This is caused by the production of autoantibodies that target RBC membrane antigens, leading to the destruction of these RBCs.
Which autoantibody class is produced in WARM AIHA?
IgG
What is the pathology of Warm AIHA?
IgG autoantibodies bine to RBC membranes optimally at 37 degrees C. This results in EXTRAVASCULAR hemolysis therefore Splenomegaly is a common feature.
It’s WARM OUTside
What are some causes of warm AIHA?
- Idiopathic
- SLE
- Alpha methyldopa
- leukemias, lymphomas
- Collagen vascular disease
What autoantibody is produced in COLD AIHA?
IgM
What is the pathology of Cold AIHA?
IgM antibodies are produced and bind optimally to the RBC membranes at cold temperatures like 0 degrees celsius. This produces complement activation and results in intravascular hemolysis. The primary site of RBC sequestration in cold AIHA is the liver.
What are some causes of Cold AIHA?
- Mycoplasma Pneumonia
- Mononucleosis
- Idiopathic
In a direct coombs test, if the RBCs are coated with IgG, what is the diagnosis?
The diagnosis would be Warm AIHA. This is a positive direct coombs test. Spherocytes may be present in Warm AIHA.
In a direct coombs test, if the RBCs are only coated with complement, what is the diagnosis?
The diagnosis would be Cold AIHA. Also, if there is a positive cold agglutinin titer, then the diagnosis is cold AIHA.
Treatment of Warm AIHA
- Glucocorticoids
- Splenectomy if non-responsive to glucocorticoids
- Immunosuppression with azathioprine or cyclophosphamide
- RBC transfusions if absolutely necessary
- Folic acid supplements