A construction worker with microcytic anemia, constipation, and neurocognitive symptoms has a peripheral blood smear most likely to show __________.
Correct Answers:
basophilic stippling
Mini-Explanation: Lead poisoning inhibits pyrimidine-5’-nucleotidase, preventing rRNA degradation and causing the aggregated rRNA to appear as basophilic stippling on a peripheral smear.
Distractors:
Heinz bodies: Seen in G6PD deficiency; represent denatured hemoglobin.
Howell-Jolly bodies: Indicate asplenia; are nuclear remnants.
Ringed sideroblasts: Found in the bone marrow, not peripheral blood, in sideroblastic anemias.
Schistocytes: Indicate mechanical hemolysis (e.g., DIC, TTP).
Mnemonic/Hook: Lead the way with Basophilic stippling for Building (construction) workers.
The effect of recombinant erythropoietin, used to treat anemia of chronic kidney disease, is primarily mediated by the __________ signaling pathway.
Correct Answer: JAK2/STAT (Janus kinase 2/Signal Transducer and Activator of Transcription)
Mini-Explanation: EPO binds to its receptor on erythroid precursors, activating the JAK2/STAT pathway to promote cell survival, proliferation, and differentiation into red blood cells.
Distractors:
Adenylate cyclase/cAMP: Used by hormones like glucagon and ADH (V2 receptor).
Arachidonic acid/Phospholipase A2: Pathway for producing prostaglandins and leukotrienes.
Nuclear receptor: Used by steroid hormones, thyroid hormone, and vitamins A & D.
Phosphatidylinositol/IP3: Used by hormones like ADH (V1 receptor) and oxytocin.
Ras/MAPK: Used by growth factors (e.g., EGF, PDGF) to stimulate cell proliferation.
Mnemonic/Hook: Erythropoietin JAKs STAT to make more red blood cells.
In acute Disseminated Intravascular Coagulation (DIC), the coagulation cascade is systemically activated, leading to increased __________ and __________, which subsequently causes consumption of platelets/factors and increased __________ to clear the clots.
Correct Answers:
thrombin production
fibrin clot formation
plasmin generation
Mini-Explanation: Widespread activation of the coagulation cascade generates excessive thrombin, which forms fibrin clots. This triggers a compensatory increase in plasmin generation to lyse the clots, leading to a consumptive coagulopathy.
Distractors: The table distractors represent incorrect combinations of increased (I) or decreased (D) activity for these three processes. Only the pattern of I, I, I is correct for DIC.
Mnemonic/Hook: DIC is a paradox: the body is simultaneously clotting and bleeding everywhere because it’s making and breaking down clots at the same time.
In the progression of iron deficiency, the first laboratory value to decrease is __________, representing the depletion of iron stores.
Correct Answer: Ferritin
Mini-Explanation: The body uses up stored iron first. Serum ferritin levels directly correlate with total body iron stores, making it the earliest marker to drop.
Distractors:
Mean Corpuscular Volume (MCV): Decreases later, during the stage of frank microcytic anemia.
Mean Corpuscular Hemoglobin Concentration (MCHC): Decreases later, during the stage of frank hypochromic anemia.
Reticulocyte Count: Becomes inappropriately low as the bone marrow cannot produce new red cells effectively.
Transferrin Saturation: Decreases in the second stage (iron-limited erythropoiesis), after stores are depleted.
Mnemonic/Hook: Iron deficiency stages: First Ferritin Falls (storage depletion), then Transferrin saturation drops and Total Iron Binding Capacity rises (transport affected), finally leading to Anemia with microcytosis and hypochromia.
In a patient with cirrhosis whose prolonged PT does not correct with vitamin K, the most likely cause is a deficiency of __________ due to impaired hepatic synthesis. This factor has the shortest __________.
Correct Answers:
Factor VII
half-life
Mini-Explanation: The liver synthesizes clotting factors. In cirrhosis, synthetic function is impaired. Factor VII has the shortest half-life (~4-6 hours), so its levels drop first, causing an early, isolated prolongation of the PT that doesn’t correct with vitamin K.
Distractors:
Dietary Vitamin K Deficiency: PT would correct with vitamin K supplementation.
Factor VIII Deficiency: Primarily affects the intrinsic pathway (prolongs aPTT, not PT) and is not synthesized in the liver.
Intrinsic Platelet Dysfunction: Causes mucocutaneous bleeding but does not prolong PT.
Von Willebrand Factor Deficiency: Affects platelet adhesion and can prolong aPTT; does not primarily affect PT.
Mnemonic/Hook: Think “VII = Very Insufficient In cirrhosis” and has the Very Insufficient Half-life.
The impaired reticulocyte response and delayed hemoglobin recovery after blood loss in older adults is best explained by an age-related __________.
Correct Answer: Decreased bone marrow mass (replaced by fat)
Mini-Explanation: Aging reduces functional hematopoietic bone marrow mass and progenitor cell diversity/reserve, limiting the ability to ramp up red blood cell production in response to acute stress like blood loss.
Distractors:
Decreased medullary cavity size: Actually increases with age due to bone loss (osteopenia/osteoporosis).
Decreased red blood cell life span: RBC lifespan is normal in healthy aging.
Increased extramedullary hematopoiesis: Occurs in pathologic states like myelofibrosis, not normal aging.
Increased marrow fibrous tissue: A feature of primary myelofibrosis, not normal aging.
Mnemonic/Hook: Aging marrow gets fatigued and can’t respond to stress. The reserve is gone.
A patient’s hematocrit rises from 44% to 50% during hospitalization for heart failure, but red blood cell mass is normal. This indicates __________ erythrocytosis, most likely due to __________.
Correct Answers:
relative
plasma volume contraction (from diuresis)
Mini-Explanation: The normal RBC mass rules out true polycythemia. The rapid hematocrit increase is due to a reduction in plasma volume, a common effect of diuretic therapy for heart failure.
Distractors:
Polycythemia Vera: A myeloproliferative neoplasm with increased RBC mass and low erythropoietin.
Hypoxic Erythrocytosis: A form of absolute polycythemia (increased RBC mass) caused by chronic low oxygen levels.
Renal Disease / Occult Neoplasia: Can cause absolute polycythemia via inappropriate erythropoietin secretion.
Mnemonic/Hook: Relative polycythemia is a “fake” high hematocrit. The red cell count is the same, there’s just less plasma (hemoconcentration). Think: Diuresis makes the blood more “concentrated.”
Warfarin-induced skin necrosis is caused by an initial, transient __________ state due to the short half-life of __________ relative to the procoagulant factors.
Correct Answers:
hypercoagulable
protein C
Mini-Explanation: Warfarin inhibits vitamin K epoxide reductase. Protein C (an anticoagulant) and Factor VII have short half-lives and drop first. The rapid loss of Protein C’s anticoagulant effect, before procoagulant factors (II, IX, X) drop, creates a temporary pro-thrombotic imbalance.
Distractors:
Allergic Drug Reaction: Presents with diffuse rash, blisters, or exfoliation, not a localized necrotic lesion.
Antithrombin Deficiency: Causes thrombosis but is not triggered by warfarin initiation.
Heparin-induced Thrombocytopenia: Causes thrombosis and is associated with heparin use (not warfarin) and thrombocytopenia.
Vitamin K Deficiency: Potentiates warfarin’s effect but does not create the specific imbalance that leads to skin necrosis.
Mnemonic/Hook: Starting warfarin can be a Catastrophe for patients with Protein C deficiency, causing clots in the skin.
The hormone __________, secreted by __________, is the central regulator of iron homeostasis and reduces intestinal iron absorption when body iron stores are high.
Correct Answers:
hepcidin
hepatic parenchymal cells (liver cells)
Mini-Explanation: Hepcidin is released by the liver in response to high iron stores. It binds to ferroportin on enterocytes and macrophages, causing its internalization and degradation, thereby trapping iron in these cells and reducing absorption from the diet.
Distractors:
Bone Marrow Macrophages: Recycle iron from senescent RBCs but do not secrete the systemic regulatory hormone.
Bone Marrow Stem Cells: Are hematopoietic precursors and do not regulate iron absorption.
Intestinal Epithelial Cells: Absorb and transport iron but are the target of the hormone, not its source.
Renal Tubular Cells: Secrete erythropoietin (regulates RBC production) and lactoferrin, not the primary iron-regulatory hormone.
Mnemonic/Hook: The Liver is the Leader in iron regulation, producing Hepcidin. High iron? Hepcidin Heps block absorption.
A patient with pancytopenia, macrocytic RBCs, and hypersegmented neutrophils on smear most likely has impaired DNA synthesis due to __________ or __________ deficiency.
Correct Answers:
Vitamin B12
Folate
Mini-Explanation: Both vitamins are essential cofactors for DNA synthesis. Their deficiency causes a nuclear-cytoplasmic asynchrony in rapidly dividing cells (like hematopoietic precursors), leading to the characteristic megaloblastic changes.
Distractors:
Iron Deficiency: Causes microcytic, hypochromic anemia, not macrocytosis or hypersegmented neutrophils.
Chronic Kidney Disease: Causes normocytic anemia due to low erythropoietin, not pancytopenia with megaloblastic changes.
Aplastic Anemia: Causes pancytopenia but with a normocytic anemia and a low reticulocyte count, lacking hypersegmented neutrophils.
Primary Myelofibrosis: Features teardrop cells and nucleated RBCs on smear, not hypersegmented neutrophils.
Aortic Stenosis: Can cause microangiopathic hemolysis with schistocytes, not macrocytosis.
Mnemonic/Hook: Big Funky Cells: B12 and Folate deficiency cause Big (macrocytic) RBCs and Funky (hypersegmented) neutrophils.
A young woman with isolated severe thrombocytopenia, mucocutaneous bleeding, and an otherwise normal physical exam and CBC most likely has __________ as the primary disease mechanism.
Correct Answer: Immune destruction of platelets (Immune Thrombocytopenic Purpura / ITP)
Mini-Explanation: ITP is an autoimmune disorder where anti-platelet antibodies (often against GPIIb/IIIa) cause premature platelet destruction by macrophages in the spleen, leading to isolated thrombocytopenia.
Distractors:
Bone Marrow Aplasia/Infiltration: Causes pancytopenia, not isolated thrombocytopenia.
Disseminated Intravascular Coagulation (DIC): Causes consumptive coagulopathy with prolonged PT/PTT and low fibrinogen.
Platelet Sequestration: Typically occurs with splenomegaly and platelet counts are usually >30,000/mm³.
von Willebrand Disease: Causes a qualitative platelet defect with a normal platelet count.
Mnemonic/Hook: ITP = Immune Thrombocytopenia. Isolated low platelets in a healthy young woman = think ITP first.
The primary genetic defect in beta-thalassemia trait is most often a point mutation causing __________, leading to reduced synthesis of beta-globin chains.
Correct Answer: Erroneous mRNA processing (e.g., splicing errors, premature stop codons)
Mini-Explanation: Most beta-thalassemia mutations are point mutations that disrupt mRNA splicing or introduce premature stop codons, not gene deletions. This reduces beta-globin chain production, creating an alpha-beta chain imbalance.
Distractors:
Cell Membrane Instability / Elevated Oxidative Stress / Insoluble Protein Formation: These are downstream consequences of the alpha-beta chain imbalance, not the primary genetic defect.
Complete Gene Deletion: This is the primary mechanism in alpha-thalassemia, not beta-thalassemia.
Impaired Heme Synthesis: Causes sideroblastic anemias, not thalassemia.
Mnemonic/Hook: Beta-thalassemia is from Broken Blueprint (point mutations affecting mRNA), while Alpha-thalassemia is from Absent gene (Alteration = deletion).
Following chemotherapy initiation for a high-burden leukemia like ALL, Tumor Lysis Syndrome causes __________, __________, and __________ due to the release of intracellular contents.
Correct Answers:
Hyperuricemia
Hyperphosphatemia
Hyperkalemia
Mini-Explanation: Rapid lysis of tumor cells releases intracellular potassium, phosphate, and nucleic acids (which are metabolized to uric acid), leading to these classic electrolyte abnormalities. LDH is also markedly elevated.
Distractors: The table distractors represent incorrect combinations of increased (I) or decreased (D) levels. Only the pattern of I, I, I, I (for Uric Acid, Phosphorous, Potassium, and LDH) is correct for Tumor Lysis Syndrome.
Mnemonic/Hook: Tumor Lysis releases the 4 H’s: Hyperuricemia, Hyperkalemia, Hyperphosphatemia, and Hypocalcemia (which occurs secondary to the hyperphosphatemia). High LDH is the marker.
According to Poiseuille’s law, the most effective way to increase the flow rate of a blood transfusion is to increase the __________ of the intravenous catheter.
Correct Answer: diameter (or radius)
Mini-Explanation: Flow is proportional to the fourth power of the radius. Doubling the radius increases flow 16-fold, making it the most impactful variable.
Distractors:
Doubling the Catheter Length: Decreases flow by doubling resistance.
Doubling the Infusion Pressure: Only doubles the flow rate.
Placing a Second Identical Catheter: Only doubles the flow rate.
Mnemonic/Hook: Radius is Royalty. A small increase in radius has a massive (R^4) effect on flow. Go for the biggest, shortest catheter.
Severe aortic stenosis can cause gastrointestinal bleeding from angiodysplasias due to a(n) __________, where high shear stress leads to the proteolytic cleavage of its large multimers.
Correct Answer: acquired von Willebrand factor deficiency (or syndrome)
Mini-Explanation: The high shear forces across the stenotic valve unfold vWF multimers, exposing a cleavage site for the ADAMTS13 protease. This depletes the most hemostatically active large multimers, causing a bleeding diathesis.
Distractors:
Decreased ADAMTS13 activity: Causes thrombotic microangiopathy (TTP), not bleeding.
Decreased hepatic synthesis: Causes a coagulopathy affecting multiple factors, not specifically linked to aortic stenosis.
Antiphospholipid antibodies: Cause thrombosis, not bleeding.
Uremic platelet dysfunction: Causes bleeding but is associated with renal failure, not aortic stenosis.
Mnemonic/Hook: Heyde’s syndrome: The triad of Aortic stenosis, Acquired vWD, and Angiodysplasia. Shear stress shears vWF.
A woman with a lifelong history of menorrhagia and epistaxis who now presents with microcytic, iron deficiency anemia most likely has an underlying __________.
Correct Answer: von Willebrand factor deficiency (von Willebrand disease)
Mini-Explanation: vWD is the most common inherited bleeding disorder. It causes mucocutaneous bleeding (e.g., heavy periods, nosebleeds), which can lead to chronic blood loss and subsequent iron deficiency anemia.
Distractors:
Antiphospholipid Syndrome / Protein C Deficiency: Cause thrombotic states, not bleeding.
Factor VIII Deficiency (Hemophilia A): Causes deep tissue, joint, and post-surgical bleeding, not primarily mucocutaneous.
Factor XIII Deficiency: Causes delayed bleeding and poor wound healing, but is very rare.
Immune Thrombocytopenia: Causes isolated low platelet counts and acute mucocutaneous bleeding, but not typically a lifelong history.
Mnemonic/Hook: Think vWD for vaginal bleeding (menorrhagia) and visceral bleeding (epistaxis, GI). It’s the classic cause of microcytic anemia in a woman without an OB/GYN structural lesion.
Von Willebrand factor (vWF) mediates platelet adhesion by binding to exposed __________ in the subendothelium and to __________ on the platelet surface.
Correct Answers:
collagen
glycoprotein Ib (GpIb)
Mini-Explanation: vWF acts as a molecular bridge. It binds to collagen exposed at sites of vessel injury and then binds to the GpIb receptor on platelets, tethering them to the injury site, especially under high shear stress.
Distractors:
Fibrin polymer: The end-product of the coagulation cascade; platelets can bind to fibrin via GpIIb/IIIa, but this is not vWF’s primary adhesive function.
Prostacyclin: A potent inhibitor of platelet aggregation produced by endothelial cells.
Protein C: An anticoagulant protein that inactivates factors Va and VIIIa.
Thrombin: A procoagulant enzyme that converts fibrinogen to fibrin; it activates platelets but is not directly bound by vWF.
Mnemonic/Hook: vWF is the “Velcro” protein: one side sticks to the Collagen wall, the other side grabs the Platelet (via GpIb).
Direct factor Xa inhibitors (e.g., apixaban) used for stroke prevention in atrial fibrillation work by directly blocking the conversion of __________ to __________.
Correct Answers:
prothrombin (Factor II)
thrombin (Factor IIa)
Mini-Explanation: Factor Xa’s primary role is to cleave prothrombin to generate active thrombin. Direct Xa inhibitors bind to the active site of Factor Xa, preventing this key step in the common coagulation pathway.
Distractors:
Conversion of Factor X to Xa: This step is upstream of the drug’s target; Xa inhibitors work after Xa is already formed.
Conversion of Fibrinogen to Fibrin: This is the action of thrombin, whose production is indirectly reduced by the drug.
Conversion of Plasminogen to Plasmin: This is the mechanism of thrombolytics (e.g., tPA), not anticoagulants.
Gamma-carboxylation of factors: This is the mechanism of warfarin (vitamin K antagonists).
Mnemonic/Hook: Think Xa-ban drugs block the “Xa to IIa” step. They stop the final common pathway right before the major amplifier (thrombin) is made.
A patient with a DVT is started on an anticoagulant that prolongs both aPTT and PT but has no effect on thrombin time. This describes the lab profile of a(n) __________.
Correct Answer: Direct Factor Xa inhibitor (e.g., apixaban, rivaroxaban)
Mini-Explanation: Factor Xa is at the convergence of the intrinsic and extrinsic pathways. Inhibiting it prolongs both aPTT and PT. Since it acts upstream, it does not affect the thrombin time, which measures the final conversion of fibrinogen to fibrin.
Distractors:
Direct Thrombin Inhibitor (e.g., dabigatran): Prolongs aPTT, PT, and Thrombin Time.
Unfractionated Heparin: Prolongs aPTT and Thrombin Time (PT is less affected).
Cyclooxygenase Inhibitor (e.g., Aspirin): Antiplatelet agent; does not significantly affect these coagulation times.
Direct Factor VIIa Inhibitor: Would primarily prolong PT only.
Mnemonic/Hook: Xa-bans block the crossroads, affecting both pathways (aPTT & PT), but don’t touch the final step (normal TT).
In acute carbon monoxide poisoning, an arterial blood gas would show a significantly elevated __________, a(n) __________ PaO₂, and a normal __________.
Correct Answers:
carboxyhemoglobin
normal
methemoglobin
Mini-Explanation: CO binds tightly to hemoglobin, drastically increasing carboxyhemoglobin. The PaO₂ (dissolved oxygen) remains normal because lung diffusion and arterial oxygen pressure are unaffected. Methemoglobin is not produced in CO poisoning.
Distractors: The table distractors represent incorrect combinations. The correct profile is High carboxyhemoglobin, Normal PaO₂, and Normal methemoglobin.
Mnemonic/Hook: CO is a “silent” poison: the blood looks well-oxygenated (normal PaO₂), but the oxygen can’t hitch a ride or get off the bus (high COHb, left-shifted curve).
In von Willebrand disease, laboratory studies typically show a normal __________ count, a normal __________, and a potentially prolonged __________ due to secondary factor VIII deficiency.
Correct Answers:
platelet
Prothrombin Time (PT)
Partial Thromboplastin Time (PTT or aPTT)
Mini-Explanation: vWD is a qualitative platelet disorder, so the platelet count is normal. The PT (extrinsic pathway) is normal. The PTT (intrinsic pathway) can be prolonged because vWF stabilizes Factor VIII; low vWF leads to increased Factor VIII degradation.
Distractors:
Decreased Platelets / Prolonged PT & PTT: Seen in consumptive coagulopathies like DIC.
Decreased Platelets / Normal PT & PTT: Seen in immune thrombocytopenia (ITP).
Normal Platelets / Prolonged PT / Normal PTT: Seen in Factor VII deficiency or warfarin effect.
Normal Platelets / Prolonged PT & PTT: Suggests a global coagulopathy, like liver disease.
Mnemonic/Hook: vWD = Variable PTT, Wonky adhesion, Defective carrier for VIII. Everything else is typically normal.
Acute hemolysis in G6PD deficiency, triggered by dapsone, presents with an __________ reticulocyte count, __________ LDH, __________ haptoglobin, and peripheral smear findings of __________.
Correct Answers:
increased
increased
decreased
Heinz bodies (or bite cells)
Mini-Explanation: Oxidative stress causes intravascular hemolysis, leading to RBC breakdown (increased LDH), hemoglobin scavenging (decreased haptoglobin), and bone marrow compensation (increased reticulocytes). Heinz bodies are the classic smear finding, with bite cells forming after splenic removal of these damaged portions.
Distractors:
Decreased Reticulocyte Count: Suggests bone marrow failure, not compensatory hemolysis.
Normal LDH/Haptoglobin: Inconsistent with active RBC destruction.
Redundant Cell Membrane (Target Cells): Seen in thalassemias and liver disease.
Basophilic Nuclear Remnants (Howell-Jolly Bodies): Indicate asplenia.
Spherical Cells (Spherocytes): More characteristic of hereditary spherocytosis or autoimmune hemolysis.
Mnemonic/Hook: G6PD Hemolysis: High LDH & Reticulocytes, Haptoglobin Hit hard, see Heinz bodies.
In hereditary spherocytosis, the loss of membrane surface area causes spherocytes, which have a(n) __________ mean corpuscular hemoglobin concentration (MCHC).
Correct Answer: Increased
Mini-Explanation: The loss of membrane without a proportional loss of hemoglobin makes the red cell denser and more concentrated, leading to an elevated MCHC. This is a highly specific finding for spherocytosis.
Distractors:
Decreased Lactate Dehydrogenase: LDH is increased in hemolysis due to RBC breakdown.
Increased Haptoglobin: Haptoglobin is decreased in hemolysis because it binds free hemoglobin and is cleared.
Increased Mean Corpuscular Volume (MCV): MCV is typically normal or slightly low in spherocytosis.
Red Blood Cell Inclusions: Not a characteristic feature of hereditary spherocytosis.
Mnemonic/Hook: Spherocytes are Small, Spherical, and Stuffed with hemoglobin (high MCHC).
In primary myelofibrosis, the finding of massive splenomegaly is due to __________, which is a compensatory response to the fibrotic, non-functional bone marrow.
Correct Answer: Extramedullary hematopoiesis (islands of hematopoietic progenitor cells in the spleen/liver)
Mini-Explanation: The fibrotic bone marrow cannot support normal hematopoiesis. Hematopoietic stem cells migrate to and proliferate in the spleen and liver, causing massive organ enlargement and the release of immature cells (teardrop cells, nucleated RBCs) into the peripheral blood.
Distractors:
Accumulation of macrophages with fibrillary cytoplasm: Seen in Gaucher disease (Gaucher cells).
Diffuse neutrophilic infiltration and follicular necrosis: Seen in acute splenic infection (e.g., septic emboli).
Dilated sinusoids and fibrosis with hemosiderin: Seen in congestive splenomegaly from portal hypertension.
Non-caseating epithelioid granulomas: Seen in sarcoidosis.
Mnemonic/Hook: Myelofibrosis forces blood production out of the marrow and into the spleen, causing it to become a “second factory” (extramedullary hematopoiesis).
