USMLE Step 1 Prep: Hematology and Oncology Quiz

Anisocytosis refers to a condition where there are varying sizes of cells present.

Poikilocytosis is a term used to describe the condition of having varying shapes of cells, particularly red blood cells. It is often seen in conditions such as anemia and certain blood disorders.

Clopidogrel and Ticlopidine irreversibly block ADP receptors, inhibiting expression of GpIIb/IIIa, resulting in inhibition of fibrinogen binding. Aspirin, Warfarin, and Lisinopril do not directly inhibit ADP-induced GpIIb/IIIa expression.

The correct answer is based on the mechanism of action of vitamin K and warfarin in the coagulation cascade. Epoxide reductase is essential for the activation of vitamin K, while warfarin specifically inhibits this enzyme, leading to decreased synthesis of important coagulation factors.

Antithrombin is synthesized in the liver and inactivates factors II, VII, IX, X, and XI. It is activated by heparin. Therefore, options 1, 2, and 3 are incorrect because they provide inaccurate information regarding the synthesis, factors inhibited, and activator of antithrombin.

Protein C is an endogenous anticoagulant that plays a crucial role in regulating blood clotting by inactivating factors V and VIII and promoting fibrinolysis. It is activated by thrombomodulin and enhances the anticoagulant function in the blood.

Factor V Leiden disease is specifically characterized by a mutation in factor V that results in resistance to protein C degradation, leading to an increased risk of blood clot formation.

tPA, or tissue plasminogen activator, plays a crucial role in the breakdown of blood clots. It is important to understand its function and activation process in the context of cardiovascular health.

Acanthocytosis is specifically related to the presence of acanthocytic red blood cells and is associated with abetalipoproteinemia and liver disease. Conditions like leukocytosis, thrombocytosis, sickle cell anemia, hemophilia, thalassemia, and polycythemia vera do not result in acanthocytosis.

Plummer-Vinson syndrome is a well-defined condition characterized by a triad of esophageal web, atrophic glossitis, and anemia, all stemming from iron deficiency. It is specifically associated with squamous cell carcinoma of the esophagus.

Microcytic, hypochromic anemia is characterized by smaller and paler red blood cells. The correct answer includes diseases like iron deficiency, alpha-thalassemia, beta-thalassemia, lead poisoning, and sideroblastic anemia which are known to present with this type of anemia. Sickle cell anemia, hemochromatosis, and megaloblastic anemia, on the other hand, are not typically associated with microcytic, hypochromic anemia.

Sideroblastic anemia is a genetic disorder affecting heme synthesis, leading to ringed sideroblasts. Treatment typically involves pyridoxine (vitamin B6) supplementation.

In heme synthesis, ?-aminolevulinic acid synthase is the rate limiting enzyme that converts glycine and succinyl coA to ?-aminolevulinic acid. This enzyme requires vitamin B6 (pyridoxine), and a deficiency can lead to sideroblastic anemia, which is an X-linked disorder.

Macrocytic anemia is characterized by the presence of abnormally large red blood cells. The three diseases mentioned in the correct answer are known to cause this type of anemia due to various underlying reasons. Iron-deficiency anemia, sickle cell anemia, and hemolytic anemia, while important types of anemia, are not typically associated with macrocytic red blood cells.

Bite cell RBCs, also known as Heinz bodies, are seen in G6PD deficiency due to oxidative damage to the RBCs. They are not characteristic findings in iron deficiency anemia, sickle cell disease, or thalassemia.

Basophilic stippling in RBCs is primarily associated with disorders such as Thalessemias, anemia of chronic disease, iron deficiency, and lead poisoning. Other conditions like Vitamin D deficiency, hypertension, and sickle cell disease do not typically cause basophilic stippling.

Megaloblastic anemia caused by B12 (cobalamin) versus folate deficiency can be differentiated based on the levels of B12, folate, methylmalonic acid, and homocysteine in the blood. Understanding these differences can help in accurate diagnosis and appropriate treatment.

The correct answer is Diphyllobothrium latum, a fish tapeworm that can cause B12 deficiency. The recommended treatment for this parasite is Praziquantel. The incorrect answers provided are for other common parasitic infections with their respective treatment options.

Hereditary spherocytosis is an autosomal dominant defect in RBC membrane/cytoskeleton proteins resulting in spherical, less pliable RBCs. The main treatment is splenectomy, after which spherocytes and Howell Jolly bodies are seen on blood smear.

G6PD deficiency is inherited in an X-linked recessive pattern. The correct information provided in the answer explains the biochemistry behind the deficiency and the specific findings on peripheral smear. The incorrect answers provide misleading inheritance patterns and incorrect peripheral smear findings to test the knowledge of the candidate.

Sickle cell anemia is caused by a specific mutation in the beta globin gene resulting in the substitution of glutamic acid with valine. This mutation leads to the characteristic sickling of red blood cells when deoxygenated, causing various complications.

Hydroxyurea's mechanism of action lies in inhibiting ribonucleotide reductase during DNA synthesis, leading to decreased production of nucleotides. Its clinical uses include the treatment of melanoma, CML, and sickle cell disease by increasing levels of fetal hemoglobin (HbF) to reduce sickling of red blood cells.

The correct complications associated with sickle cell anemia include specific issues related to the disease such as aplastic crisis, autosplenectomy, and splenic sequestration crisis, among others. The incorrect answers provided do not align with the known complications of sickle cell anemia.

Pyruvate kinase is an enzyme that plays a key role in glycolysis, converting PEP (phosphoenolpyruvate) to pyruvate and producing ATP. Deficiency of pyruvate kinase, particularly in an autosomal recessive pattern, leads to a specific type of anemia characterized by rigid RBCs and decreased ATP levels, resulting in normocytic, normochromic intrinsic hemolytic anemia.

Anemia of chronic disease is not caused by iron overload, decreased erythropoietin production, or accelerated destruction of red blood cells. The main mechanism involves the release of hepcidin in chronic inflammation.

The direct Coombs test is used to detect antibodies that are bound to the surface of red blood cells. It is commonly used to diagnose autoimmune hemolytic anemia and hemolytic disease of the newborn.

The indirect Coomb's test involves adding patient's serum to RBCs to detect the presence of anti-RBC surface Ig's. The correct answer involves agglutination of RBCs when anti-RBC antibodies are present.

Warm autoimmune hemolytic anemias are characterized by the presence of warm agglutinins, typically IgG antibodies. The correct answer lists some of the conditions associated with this type of hemolytic anemia and the Ig class involved.

Cold agglutinins are specific autoantibodies that bind to red blood cells at low temperatures. In the case of Mycoplasma pneumoniae and infectious mononucleosis, cold agglutinins are IgM mediated. The incorrect answers provided do not align with the characteristic features of cold agglutinin disease.