USMLE Step 2: HEME/ONC Flashcards
Effects of Heparain
Increases PTT, activates antithrombin III and affects the INTRINSIC pathway, and decreases fibrinogen.
Antidote for heparin
Protamine Sulfate
Effects of Warfarin
Increases PT, extrinsic pathway
How is the intrinsic pathway measured?
PTT
How is intrinsic pathway initiated?
By exposure of collagen following vascular trauma
how is extrinsic pathway measured?
by PT
How is extrinsic pathway initiated?
By endothelium-produced tissue factor
intrinsic pathway
12, 11, 9, 8
Intrinsic pathway
7 (3 is cofactor)
Common pathway
10 (activated by 8 and 7), 5, prothrombin, thrombin
What does thrombin activate?
Fibrinogen & 13 (13 does cross linking of fibrin)
Labs in hemophilia
PT, thrombin time, fibrinogen, and bleeding time are NORMAL.
aPTT is PROLONGED!!
What is the inheritance of hemophilia?
X-linked
What is the inheritance of von Willebrand’s Disease?
Autosomal dominant
Labs in vWD
Platlet count and PT are NORMAL
aPTT and Bleeding time are PROLONGED
What is DIC?
Deposition of fibrin in small blood vessels leading to thrombosis and end-organ damage. Depletion of clotting factors and platlets leads to a bleeding diathesis
What is thrombotic thrombocytopenic purpura?
A bleeding disorder due to platelet microthrombi that block off small blood vessels, leading to end-organ ischemia and dysfunction
**similar to DIC
What happens to RBCs in TTP?
They become fragmented by contact with the microthrombi leading to hemolysis (microangiopathic hemolytic anemia)
What are the 5 s/sx of TTP?
- Low platlet count
- Microangiopathic hemolytic anemia
- Neurologic Changes
- Impaired Renal Function
- Fever
How is TTP diagnosed?
3/5 of the s/sx + schistocytes, low platlets, and rising creatinine
What else is on the same spectrum of disease as TTP?
HUS (which has more severe elevations of creatinine) & HELLP
What are the 3 causes of microangiopathic hemolytic anemia?
HUS, TTP, DIC
What is idiopathic thrombocytopenic Purpura?
IgG antibodies formed against the patient’s platelets
What do lymphoblasts differentiate into?
B & T Cells
What do myeloblasts differenciate into?
Neutrophils, Eosinophils, and Basophils
What is the value of looking at the retic?
2.5 hemolysis/hemorrhage
Causes of microcytic anemia?
TICS: thalassemia, iron deficiency, chronic disease, sideroblastic anemia
What is the Schilling test?
The patient is first given unlabeled B12 IM to saturate B12 receptors in the liver, followed by an oral challenge of radiolabeled B12. The radiolabeled B12 will pass into the urine if it is properly absorbed, as the liver’s B12 receptors will be saturated from the IM dose
What does it mean is radiolabeled B12 is in the urine for the schilling test?
It means there is a dietary B12 deficiency
What doe sit mean if there is no radiolabeled B12 in the urine for the schilling test?
Consider pernicious anemia, bacterial overgrowth, or pancreatic enzyme deficienc
What happens to MMA and homocysteine in B12 deficiency?
Both are elevated
What happens to MMA and homocysteine in folate deficiency
MMA is normal & homocysteine is elevated
What is PNH?
A disorder in which blood cell sensitivity to complement activation is increased; patients are prone to thrombotic events
LDH, indirect bilirubin, and haptoglobin in hemolytic anemia
LDH: elevated
Indirect bilirubin: elevated
Haptoglobin: decreased
how do patients with aplastic anemia present?
Pancytopenic- lack of RBCs, WBCs, and platelets
What does the indirect Coombs’ Test detect?
Antibodies to RBCs in the patients serum
What does the direct Coombs test detect?
Sensitized erythrocytes
What is the #1 and #2 cause of osteomyelitis in patients with sickle cel disease?
#1: S. aureus #2: Salmonella
Health maintenance in patients with sickle cell disease?
Treating cholelithiasis with lap chole, chronic folate supplementation, pneumococcal vaccination
Thalassemia: 0/4 alpha-chain
hydrops fetalis- patients die in utero
Thalassemia: 1/4 alpha-chain
Hemoglobin H disease (severe hypochromic, microcyticc anemia with chronic hemolysis, splenomegaly, jaundice, and cholelithiasis; skeletal changes
Thalassemia: 2/4 alpha
Alpha-thal trait; patients have low MCV but are usually asymptomatic
Thalassemia: 3/4 alpha
Silent carrier patients have no s/sx of disease
What is polycythemia vera from?
Clonal proliferation of a pluripotent marrow stem cell due to a JAK2 mutation
What cell line is affected in polycythemia vera?
ALL cell lines are affected- RBCs are most affected
What are the types of porphyrias?
- Acute Intermittent
- Porphyria cutanea tarda
3 Erythropoietic porphyria
Leukocyte Alkaline Phosphatase (LAP)
Elevated from a leukemoid reaction and decreased in hematologic malignancy
Effective of glucose on porphyria
Glucose provides negative feedback to the heme synthetic pathway, so high doses may be administered to decrease heme synthesis during an attack
AML and ALL
Marrow that is infiltrated wtih blast cells (>20-30%); in AML the leukemic cells are myeloblasts; in ALL they are lymphoblasts
What is the treatment for M3 AML?
all-trans-retinoic acid
Genetic mutation in M3 AML?
Translocation involving chromosomes 15 & 17
What do myeloblasts look like?
Large (2-4x RBC), lots of cytoplasm, conspicuous nucleoli, fine granules, +myeloperoxidase
What do lymphoblasts look like?
Smaller (1.5-3x RBC), less cytoplasm, inconspicuous nucleoli, =myeloperoxidase
Age groups for leukemia’s
ALL: 60
Triad for multiple myeloma
Anemia, renal failure, and bone pain
What is neutropenia?
Absolute neutrophil count <1500
How is ANC calculated?
(WBC) X (%bands + % segmented neutrophils)
What bacterial infections are associated with acute neutropenia?
S. aureus, Pseudomonas, E coli, Proteus, Klebsiella
How is fever in a patient with neuropenia treated?
Broad-spectrum antibiotic (cefepime)
Pathomechanism of hyperacute rejection
Preformed antibodies
Pathomechanism of acute rejection
T-cell mediated
Pathomechanism of chronic rejection
Chronic immune reaction causing fibrosis
Neoplasm associated with down syndrome
ALL (we ALL go down)
Neoplasm associated with xeroderma pigmentosum
SCC and BCC carcinomas of the skin
Neoplasm associated with pernicious anemia
gastric adenocarcinoma
Neoplasm associated with tuberous sclerosis
astrocytoma and cardiac rhabdomyoma
Neoplasm associated with actinic keratosis
SCC of skin
Neoplasm associated with Plummer-vinson syndrome
SCC of esophagus
Neoplasm associated with Paget’s disease of bone
secondary osteosarcoma and fibrosarcoma
Neoplasm associated with AIDS
Aggressive malignant NHLs and Kaposi’s sarcoma
Neoplasm associated with acanthosis nigricans
Visceral malignancy (stomach, lung, breast, uterus)
