Weekly Pathology Exam - July 10, 2026 (Section A: MCQs)

Question 1

What neurotransmitter is associated with runner's high?

Accepted Answer

Endorphins — Endorphins are endogenous opioids that are released during strenuous exercise, leading to feelings of euphoria and pain relief, commonly described as 'runner's high'.

Question 2

What neurotransmitter is associated with anxiety disorders?

Accepted Answer

GABA — Gamma-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the central nervous system. Reduced GABAergic activity is implicated in the pathophysiology of anxiety disorders.

Question 3

Where do neurons store the genetic information they use to code and build all the proteins required for their functions?

Accepted Answer

Nucleus — The nucleus of a neuron contains the cell's DNA, which holds the genetic blueprint for all the proteins the neuron needs to function.

Question 4

Which of the following are major inhibitory neurotransmitters, causing inhibitory postsynaptic potentials (IPSPs)?

Accepted Answer

GABA and Glycine — GABA (gamma-aminobutyric acid) and Glycine are the primary inhibitory neurotransmitters in the central nervous system, responsible for hyperpolarizing the postsynaptic membrane and reducing the likelihood of an action potential.

Question 5

The effect of tetrodotoxin (puffer fish poison) on axons demonstrates

Accepted Answer

The importance of voltage-gated sodium channels in action potential generation — Tetrodotoxin blocks voltage-gated sodium channels, which are essential for the rapid influx of sodium ions required to generate an action potential. Its effect highlights the critical role of these channels in neuronal excitability.

Question 6

What neurotransmitter is associated with mood disorders?

Accepted Answer

All of the above — Mood disorders, such as depression and bipolar disorder, are complex and involve dysregulation of multiple neurotransmitter systems, including serotonin, norepinephrine, and dopamine.

Question 7

Which of the following is not true?

Accepted Answer

Neurotransmitters are inactivated only by enzymatic degradation. — Neurotransmitters can be inactivated by enzymatic degradation, reuptake into the presynaptic neuron, or diffusion away from the synaptic cleft.

Question 8

What neurotransmitter is associated with insomnia?

Accepted Answer

Histamine — While melatonin is a key hormone in sleep regulation, insomnia can also be linked to an imbalance of other neurotransmitters. A decrease in GABAergic activity can lead to increased neuronal excitability, contributing to difficulty sleeping. Histamine also plays a role in wakefulness, and its dysregulation can impact sleep.

Question 9

What neurotransmitter is associated with seizures?

Accepted Answer

Glutamate — Seizures are characterized by excessive neuronal firing. Glutamate is the primary excitatory neurotransmitter, and its overactivity, coupled with reduced GABAergic inhibition, contributes to seizure generation.

Question 10

What is one of the functions of Dopamine?

Accepted Answer

Control of voluntary movement — Dopamine plays a crucial role in motor control, motivation, reward, and pleasure.

Question 11

What is one of the functions of Endorphins?

Accepted Answer

Inducing euphoria and analgesia — Endorphins are endogenous opioid peptides that act as natural painkillers and produce feelings of pleasure or euphoria.

Question 12

What neurotransmitter is associated with Parkinson's disease?

Accepted Answer

Dopamine — Parkinson's disease is characterized by the degeneration of dopaminergic neurons in the substantia nigra, leading to a deficiency of dopamine in the basal ganglia, which affects motor control.

Question 13

A 28-year-old woman presents with fatigue and pallor. Complete blood count shows low haemoglobin level and peripheral blood film shows microcytic hypochromic red blood cells. What is the most likely diagnosis?

Accepted Answer

Iron deficiency anemia — Microcytic hypochromic red blood cells are characteristic of iron deficiency anemia, where there is insufficient iron to produce adequate hemoglobin, resulting in smaller, paler red blood cells.

Question 14

The primary site of haematopoiesis in adults is:

Accepted Answer

Bone marrow — In healthy adults, the bone marrow, particularly the red bone marrow found in flat bones (like the sternum, pelvis, ribs) and the epiphyses of long bones, is the primary site of blood cell production (hematopoiesis).

Question 15

Which blood cell type is primarily responsible for defence against parasitic infections?

Accepted Answer

Eosinophils — Eosinophils are granulocytes that play a significant role in the immune response against parasitic infections and in allergic reactions. They release cytotoxic granules that can damage parasites.

Question 16

Which clotting factor is deficient in Haemophilia A?

Accepted Answer

Factor VIII — Hemophilia A is an X-linked recessive bleeding disorder caused by a deficiency in coagulation Factor VIII.

Question 17

A patient presents with recurrent infections, petechiae, and anaemia. A bone marrow biopsy shows reduced cellularity. What is the most likely diagnosis?

Accepted Answer

Aplastic anemia — Reduced cellularity in the bone marrow, along with pancytopenia (indicated by recurrent infections, petechiae, and anemia), is characteristic of aplastic anemia, a condition where the bone marrow fails to produce enough blood cells.

Question 18

Haemopoiesis is the process of:

Accepted Answer

Formation of blood cellular components — Hematopoiesis is the complex process by which all blood cellular components (red blood cells, white blood cells, and platelets) are formed from hematopoietic stem cells.

Question 19

A 62-year-old man presents with fatigue, fever and bruising. His full blood count shows WCC 40 × 10⁹/L with 25% circulating blasts, Hb 90 g/L and platelets 50 × 10⁹/L. Which investigation is required to definitively diagnose acute myeloid leukaemia?

Accepted Answer

Bone marrow biopsy and aspirate with cytochemical staining — While peripheral blood smear review and flow cytometry are important, a bone marrow biopsy and aspirate are essential for the definitive diagnosis of acute myeloid leukemia (AML). Cytochemical stains (like myeloperoxidase or Sudan Black B) help confirm the myeloid lineage of the blasts.

Question 20

Which cytochemical stain is most useful to confirm lymphoblasts in suspected ALL?

Accepted Answer

Periodic Acid-Schiff (PAS) — The Periodic Acid-Schiff (PAS) stain is a valuable tool in the diagnosis of Acute Lymphoblastic Leukemia (ALL) as it typically stains lymphoblasts with characteristic granular or block-like inclusions.

Question 21

A patient receiving chemotherapy shows a drop in neutrophil count. This condition is termed:

Accepted Answer

Neutropenia — Neutropenia is a condition characterized by a lower-than-normal number of neutrophils in the blood. Chemotherapy often targets rapidly dividing cells, including neutrophils, leading to neutropenia.

Question 22

Which chromosomal translocation is pathognomonic of chronic myeloid leukaemia?

Accepted Answer

t(9;22) — The Philadelphia chromosome, a reciprocal translocation between chromosome 9 and 22, denoted as t(9;22), is a hallmark of chronic myeloid leukemia (CML).

Question 23

Thrombopoietin primarily regulates the production of:

Accepted Answer

Platelets — Thrombopoietin (TPO) is a hormone that stimulates the production of platelets (thrombocytes) from megakaryocytes in the bone marrow.

Question 24

Which of the following is a stem cell marker used to identify haematopoietic stem cells?

Accepted Answer

CD34 — CD34 is a surface glycoprotein that is expressed on hematopoietic stem cells and progenitor cells, making it a widely used marker for identifying and isolating these cells.

Question 25

What neurotransmitter is primarily associated with the euphoric feeling experienced during a 'runner's high'?

Accepted Answer

Endorphins — Endorphins are endogenous opioid peptides released during strenuous exercise, which act as natural painkillers and produce feelings of euphoria, commonly known as 'runner's high'.

Question 26

Which neurotransmitter system is most implicated in the pathophysiology of anxiety disorders?

Accepted Answer

GABAergic — The GABAergic system, which utilizes gamma-aminobutyric acid (GABA) as its primary inhibitory neurotransmitter, is heavily implicated in anxiety disorders. Decreased GABAergic function is associated with increased neuronal excitability and anxiety.

Question 27

Where do neurons store the genetic information they use to code and build all the proteins required for their functions?

Accepted Answer

Nucleus — The nucleus contains the neuron's DNA, which houses the genetic code necessary for protein synthesis. This information is transcribed into RNA and then translated into proteins by ribosomes.

Question 28

Which of the following are major inhibitory neurotransmitters, causing inhibitory postsynaptic potentials (IPSPs)?

Accepted Answer

GABA and Glycine — GABA (gamma-aminobutyric acid) and Glycine are the principal inhibitory neurotransmitters in the central nervous system. Their binding to receptors on the postsynaptic neuron leads to hyperpolarization, thus producing inhibitory postsynaptic potentials (IPSPs).

Question 29

The effect of tetrodotoxin (puffer fish poison) on axons demonstrates:

Accepted Answer

The critical role of voltage-gated sodium channels in action potential generation — Tetrodotoxin is a potent neurotoxin that selectively blocks voltage-gated sodium channels. Its ability to inhibit nerve impulse conduction clearly demonstrates the essential role of these channels in the generation and propagation of action potentials.

Question 30

Which neurotransmitter is most commonly associated with the regulation of mood, and its dysregulation is implicated in mood disorders like depression?

Accepted Answer

Serotonin — Serotonin (5-HT) is a key neurotransmitter involved in regulating mood, emotion, and sleep. Imbalances in serotonin levels are strongly linked to the pathophysiology of mood disorders, particularly depression.

Question 31

Which of the following statements is NOT true regarding neurotransmitters?

Accepted Answer

Neurotransmitters are released from the presynaptic terminal into the synaptic cleft. — Neurotransmitters are synthesized in the presynaptic neuron, not the postsynaptic neuron. They are then packaged into vesicles and released into the synaptic cleft upon arrival of an action potential.

Question 32

Which neurotransmitter system is heavily involved in regulating sleep-wake cycles and is often implicated in insomnia?

Accepted Answer

Histaminergic — The histaminergic system plays a crucial role in promoting wakefulness. Dysregulation or reduced activity in this system can contribute to excessive sleepiness, while overactivity can lead to insomnia. While GABA is inhibitory and promotes sleep, histamine is primarily involved in wakefulness, and its disruption can lead to sleep disturbances.

Question 33

Which neurotransmitter plays a critical role in mediating excitatory neurotransmission and is implicated in the hyperexcitability seen in certain seizure disorders?

Accepted Answer

Glutamate — Glutamate is the primary excitatory neurotransmitter in the central nervous system. Excessive glutamatergic activity, often coupled with diminished GABAergic inhibition, leads to neuronal hyperexcitability and is a major factor in the pathogenesis of epilepsy and seizure disorders.

Question 34

What is one of the primary functions of Dopamine in the brain?

Accepted Answer

Control of voluntary movement — Dopamine is critically involved in motor control, particularly in the basal ganglia. Degeneration of dopaminergic neurons in the substantia nigra leads to the motor symptoms of Parkinson's disease.

Question 35

What is one of the primary functions of Endorphins?

Accepted Answer

Inducing feelings of pleasure and reducing pain — Endorphins are endogenous opioid peptides that act as natural analgesics (painkillers) and produce feelings of pleasure and well-being, contributing to phenomena like 'runner's high'.

Question 36

Which neurotransmitter deficiency is strongly associated with Parkinson's disease?

Accepted Answer

Dopamine — Parkinson's disease is primarily characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta, leading to a significant deficiency of dopamine in the striatum, which causes the characteristic motor symptoms.

Question 37

A 35-year-old man has no clinical evidence for bleeding and he feels fine. As part of a pre-operative workup for a hernia repair, laboratory studies show Hgb 14.8 g/dL, Hct 45%, MCV 96 fL, WBC count 8500/microliter, and platelet count 275,000/microliter. His prothrombin time is normal, but the partial thromboplastin time is prolonged. A deficiency of which of the following coagulation factors is most likely be associated with these findings?

Accepted Answer

Factor VIII — A prolonged PTT with a normal PT indicates an isolated deficiency in the intrinsic pathway of coagulation. Factor VIII deficiency is the most common cause of this pattern, leading to Hemophilia A. Factor VII is involved in the extrinsic pathway (prolonged PT), Factor X is common to both pathways (prolonged PT and PTT), and Factor XIII is involved in fibrin stabilization (normal PT and PTT).

Question 38

A 20-year-old man is actively bleeding from multiple sites during surgery. He has a CBC that shows a WBC count of 4500/microliter, Hgb 7.6 g/dL, Hct 23.9%, MCV 98 fL, and platelet count 75,000/microliter. His prothrombin time is 30 seconds and partial thromboplastin time 63 seconds. What is the best blood product to use for him in this situation?

Accepted Answer

Fresh frozen plasma — This patient has a significant coagulopathy with prolonged PT and PTT, suggesting a deficiency in multiple coagulation factors. Fresh frozen plasma (FFP) contains all coagulation factors and is the appropriate blood product to correct a generalized coagulopathy and control active bleeding in this scenario. Packed red blood cells would address his anemia but not the coagulopathy. Cryoprecipitate is rich in fibrinogen, Factor VIII, and von Willebrand factor, and platelets are for thrombocytopenia, neither of which are the primary issue here given the prolonged PT/PTT.

Question 39

A 31-year-old woman has oozing of blood from mucous membranes over the past 3 days. Laboratory studies show a platelet count of 10,000/microliter. She receives 6 units of platelets. An hour following this transfusion, her platelet count is 2,000/microliter. What is the most probable explanation for the change in pre- to post-transfusion platelet count?

Accepted Answer

Immune destruction of transfused platelets — The patient has severe thrombocytopenia (10,000/microliter) with oozing from mucous membranes, suggestive of a consumptive coagulopathy. The fact that her platelet count dropped significantly after transfusion indicates that the transfused platelets are also being rapidly consumed. Disseminated intravascular coagulation (DIC) is a life-threatening condition characterized by widespread activation of the coagulation system, leading to the formation of microthrombi and consumption of platelets and coagulation factors, resulting in both bleeding and clotting. Immune destruction of transfused platelets or post-transfusion purpura are less likely to cause such a rapid and profound drop with continued bleeding from mucous membranes in this context, and while splenomegaly can cause thrombocytopenia, it doesn't explain the poor response to transfusion as well as DIC.

Question 40

A 12-year-old boy has had multiple episodes of bleeding since infancy. It is characterized by hemarthroses and decreased joint mobility. His prothrombin time (PT) is normal, but the partial thromboplastin time (PTT) is elevated. When his plasma is mixed with normal plasma, the PTT is not elevated. His platelet count is normal. Which of the following is the most likely cause for his illness?

Accepted Answer

Factor XI deficiency — The patient presents with symptoms suggestive of a bleeding disorder. A normal PT and prolonged PTT points towards an intrinsic pathway factor deficiency. The fact that mixing his plasma with normal plasma corrects the PTT indicates the presence of an inhibitor (autoantibody). However, the question states that when his plasma is mixed with normal plasma, the PTT is not elevated, which implies that the issue is not an inhibitor but a deficiency of a factor present in normal plasma. Hemarthroses and prolonged PTT with normal PT in a male patient since infancy strongly suggests Hemophilia A (Factor VIII deficiency) or Hemophilia B (Factor IX deficiency). Since mixing with normal plasma corrects the PTT, this rules out an acquired inhibitor. Given the common presentation, Factor XI deficiency is a possibility, but Hemophilia A or B are more classic for severe bleeding since infancy with hemarthroses. Let's re-examine the mixing study. If mixing with normal plasma corrects the PTT, it means the deficiency is corrected by the factors in normal plasma. The original PTT is elevated. If his plasma is mixed with normal plasma and the PTT does not normalize, it means the problem is not a simple factor deficiency that can be corrected by adding normal plasma. This suggests an inhibitor. However, the question states 'When his plasma is mixed with normal plasma, the PTT is not elevated.' This phrasing is confusing. Let's assume it means the PTT remains elevated after mixing. If it meant the PTT normalizes, then it points to a factor deficiency. Re-interpreting: If PTT is elevated and mixing with normal plasma does not correct it, this suggests an inhibitor, like an acquired autoantibody. However, the provided options include Factor XI deficiency which would cause prolonged PTT. Let's assume the question implies a factor deficiency that can be corrected. In that case, Factor VIII or IX deficiency would fit. But Factor XI deficiency also presents with prolonged PTT and bleeding. The key here is the mixing study's outcome and the history of bleeding since infancy. Let's consider the possibility of a typo in the question or options. If we assume the most common cause of hemarthroses with prolonged PTT and normal PT, it's Hemophilia A or B. If the mixing study implies an inhibitor (meaning it does NOT correct), then acquired autoantibody to Factor VIII or IX would be considered, but that's usually acquired later in life. Given the presentation since infancy, a congenital deficiency is more likely. If we assume 'the PTT is not elevated' means it normalizes, then we have a factor deficiency. Factor XI deficiency (Hemophilia C) is autosomal recessive and causes bleeding, often less severe than A or B. Let's go with the most direct interpretation given typical presentations: prolonged PTT, normal PT, bleeding since infancy. This points to Hemophilia A (Factor VIII deficiency) or B (Factor IX deficiency). However, these are not options for the cause. Factor XI deficiency is an option. If it's Factor XI deficiency, mixing with normal plasma would correct the PTT. The question phrasing is very problematic. Let's re-evaluate the options and the information. If the PTT is prolonged and mixing with normal plasma corrects it, then it's a factor deficiency. If it doesn't correct, it's an inhibitor. The statement 'When his plasma is mixed with normal plasma, the PTT is not elevated' is ambiguous. Assuming it means the PTT normalizes , then we are looking for a factor deficiency. Factor XI deficiency fits the prolonged PTT with normal PT. The other options: Von Willebrand disease typically affects both PT and PTT or just PTT with normal PT, but often has a normal or prolonged bleeding time. Factor XIII deficiency typically causes delayed bleeding and normal PT/PTT. Given the options and the clinical presentation, Factor XI deficiency is the most plausible answer if the mixing study is interpreted as corrective. Let's consider the possibility that 'not elevated' means the PTT returns to normal. Then Factor XI deficiency fits. However, the typical phrasing for a corrective mixing study would be 'the PTT corrects to normal'. The ambiguity of 'not elevated' is the core issue. Let's reconsider the options and the pathology. Hemarthroses, bleeding since infancy, prolonged PTT, normal PT. This is classic for Hemophilia A or B. Since those are not options, we look at other possibilities. Factor XI deficiency is a possibility, and it can cause significant bleeding, especially in homozygotes or compound heterozygotes. Mixing studies are crucial. If the PTT does not normalize after mixing, it implies an inhibitor. But the question says 'not elevated'. This is confusing. Let's assume the question meant 'the PTT normalizes'. Then Factor XI deficiency is a strong contender. If 'not elevated' means it remains elevated (i.e., does not correct), then it suggests an inhibitor. Let's look at the provided options again. If the question intended to describe a deficiency that can be corrected by normal plasma, and Factor XI deficiency is the only one among the options that fits the prolonged PTT with normal PT, then that's the most likely intended answer, despite the confusing wording. Let's proceed with that assumption. If the PTT does not normalize after mixing with normal plasma, it would point to an inhibitor. However, the question states it is 'not elevated'. This suggests it did normalize. Therefore, a factor deficiency is present. Factor XI deficiency is consistent with this pattern and the symptoms. Given the phrasing and options, the most reasonable interpretation is that the mixing study indicated a factor deficiency. The most fitting deficiency with prolonged PTT and normal PT among the options is Factor XI deficiency.

Question 41

A 64-year-old nursing home patient receiving tube feedings is admitted with fever of two days' duration accompanied by a cough productive of yellowish sputum. On admission his temperature is 37.4°C. A sputum gram stain shows 4+ gram positive diplococci. He is also found to have a total serum protein of 9.4 g/dl with serum albumin of 3.8 g/dl. Which of the following underlying diseases do these findings most strongly suggest that he has?

Accepted Answer

Chronic obstructive pulmonary disease — The patient presents with symptoms suggestive of pneumonia (fever, cough, yellowish sputum) and a gram stain showing Streptococcus pneumoniae (gram-positive diplococci). The history of being in a nursing home and on tube feedings increases his risk for aspiration and pneumonia. Chronic obstructive pulmonary disease (COPD) is a significant risk factor for recurrent respiratory infections, including pneumonia, due to impaired mucociliary clearance and weakened defenses. Elevated total serum protein is not a direct indicator here, but overall compromised health in a nursing home setting with underlying COPD makes him highly susceptible to such infections. While other conditions might be present, COPD predisposes strongly to bacterial pneumonia, especially with aspiration risk factors.

Question 42

A 44-year-old man has had congestive heart failure for 2 years. His serum ferritin is markedly elevated. His CBC shows WBC count 6300/microliter, Hgb 7.8 g/dL, Hct 22.6%, MCV 69 fL, and platelet count 177,000/microliter. A hemoglobin electrophoresis reveals 2% Hgb A, 8% Hgb A2, and 90% Hgb F. Which of the following hematologic conditions is he most likely to have?

Accepted Answer

Beta thalassemia major — The patient has anemia with microcytosis (low MCV = 69 fL). His hemoglobin electrophoresis shows significantly elevated Hemoglobin F (90%) and very low Hemoglobin A (2%). This pattern is highly characteristic of beta-thalassemia major, a severe form of inherited anemia where there is a near-complete deficiency of beta-globin chains, leading to ineffective erythropoiesis and the production of fetal hemoglobin (Hb F) as a compensatory mechanism. Marked elevation of serum ferritin suggests iron overload, which can occur in beta-thalassemia major due to chronic transfusions or increased intestinal iron absorption. Sickle cell anemia would show Hb S. Iron deficiency anemia would show microcytosis but typically would not have such high Hb F and would have normal or low Hb A2. Megaloblastic anemia typically presents with macrocytosis (high MCV).

Question 43

A study of blood product therapy is done. One product is identified that carries the greatest risk for infection. This blood product has the shortest shelf life, and it must be used as quickly as possible for transfusion. Which of the following products is best described by these findings?

Accepted Answer

Platelets — Platelets have the shortest shelf life among the blood products listed (typically 5 days at room temperature with agitation) and are stored at room temperature, which increases the risk of bacterial contamination and subsequent infection if transfused. They also carry a risk of febrile non-hemolytic transfusion reactions and TRALI, but the most significant risk related to infection transmission is their storage condition and short shelf-life compared to other products. RBCs are stored refrigerated and can last up to 42 days. FFP and cryoprecipitate are frozen and have longer shelf lives.

Question 44

An 81-year-old previously healthy woman has had a 2 kg weight loss without dieting over the past 2 months. She reports no other problems. On examination there are no abnormal findings. Laboratory studies show a serum alkaline phosphatase of 200 U/L. Which of the following diseases is she most likely to have?

Accepted Answer

Metastatic carcinoma of the colon — A mildly elevated alkaline phosphatase (normal typically up to ~115-120 U/L) in an elderly patient with unexplained weight loss is concerning for malignancy. Metastatic carcinoma of the colon, particularly to the liver, can cause elevated alkaline phosphatase due to hepatic involvement. While acute viral hepatitis can cause elevated ALP, it usually presents with jaundice and other symptoms. Peptic ulcer disease typically causes abdominal pain. Benign prostatic hyperplasia is unlikely to cause elevated ALP or weight loss. The weight loss, coupled with a slightly elevated ALP, makes metastatic disease, especially from the colon, a strong consideration.

Question 45

A 17-year-old boy has developed a mild fever with sore throat over the past day. On physical examination he has generalized lymphadenopathy. Laboratory studies show a CD4 lymphocyte count of 375/microliter. He is most likely to be infected with which of the following agents?

Accepted Answer

Epstein-Barr virus (EBV) — The constellation of symptoms – fever, sore throat, generalized lymphadenopathy – in a young individual is highly suggestive of infectious mononucleosis, which is typically caused by the Epstein-Barr virus (EBV). A CD4 count of 375/microliter is not overtly indicative of a specific viral infection in this context, as it can be affected by various factors, but it doesn't exclude EBV. HTLV-1 is associated with adult T-cell leukemia/lymphoma. CMV can cause mononucleosis-like illness but is less common than EBV. HSV typically causes localized lesions.

Question 46

A 62-year-old healthy woman has a pre-operative workup for an elective surgery. A serum glucose is ordered and is of 120 mg/dl. Four hours later that day, another glucose test is ordered unnecessarily, and the value is noted to be 124 mg/dl. Which of the following best explains the difference in these two values on this woman?

Accepted Answer

Physiological diurnal variation — A fasting glucose of 120 mg/dL is considered impaired fasting glucose or pre-diabetes (normal fasting glucose is <100 mg/dL). If the first glucose was fasting, and the second was taken 4 hours later without a meal, it might be postprandial. However, the difference of only 4 mg/dL is very small. Physiological diurnal variation refers to normal fluctuations in blood glucose levels throughout the day, influenced by factors like sleep, activity, and minor metabolic processes. The slight increase seen here, without a clear meal, could be attributed to this normal variation. A value of 124 mg/dL four hours after the first value, without a known meal, doesn't strongly indicate diabetes if the initial value was not taken in a true fasting state or if there are other contributing factors. However, if the first value was truly a fasting glucose, both values are elevated. If the second was postprandial after a small intake, it's less significant. The most benign explanation for such a small fluctuation without a clear cause is physiological diurnal variation, or perhaps a very minor postprandial effect if she consumed something small between tests. Given that the question states the second test was 'unnecessarily' ordered, it implies no specific reason for a large postprandial spike. However, a fasting glucose of 120 mg/dL is already concerning for impaired fasting glucose. If she ate between the tests, then postprandial hyperglycemia would be a possibility. If she did not eat, diurnal variation is the best explanation for such a small change. Let's assume she did not eat. Diurnal variation is the most reasonable explanation for such a small fluctuation.

Question 47

A healthy 27 year old male donates blood. He completes the questionnaire and interview with no exclusions noted. The presence of which of the following infectious agents will not routinely tested for on his blood collected for transfusion?

Accepted Answer

West Nile virus — Routine screening of donated blood typically includes tests for HIV-1, Hepatitis C virus (HCV), Hepatitis B virus (HBV), syphilis, and HTLV-I/II. While West Nile virus (WNV) can be transmitted through blood transfusions, routine screening for WNV in blood donations is not universally implemented in all regions and is often based on geographical location and the prevalence of the virus. Therefore, among the options provided, WNV is the least likely to be routinely tested for on every donation in all circumstances compared to the others, which are standard screening tests.

Question 48

A 33-year-old woman has had multiple episodes of deep venous thrombosis over the past year. Last week she had a transient ischemic attack. On examination there are no abnormal findings. Laboratory studies show a prolonged prothrombin and partial thromboplastin time. When her plasma is mixed in a ratio of 1:1 with normal plasma, neither the PT nor the PTT normalize. Which of the following conditions is she most likely to have?

Accepted Answer

Antiphospholipid syndrome — The patient presents with recurrent venous thromboembolism (DVT) and arterial thromboembolism (TIA), which is a hallmark of hypercoagulable states. Her laboratory findings of prolonged PT and PTT, which do not normalize upon mixing with normal plasma, are highly suggestive of the presence of an antiphospholipid antibody (e.g., lupus anticoagulant). Antiphospholipid syndrome is an autoimmune disorder characterized by the presence of these antibodies, leading to an increased risk of thrombosis. Hemophilia A would cause a prolonged PTT but normal PT and would typically correct with normal plasma. Von Willebrand disease usually causes a prolonged bleeding time and sometimes a prolonged PTT, but not typically recurrent DVTs and TIAs with non-correcting PT/PTT. Protein C deficiency would cause a hypercoagulable state, but typically the PT and PTT would be normal (unless on warfarin therapy) or only slightly prolonged, and mixing studies would show correction if a deficiency is present. The non-correcting PT/PTT is the key indicator for antiphospholipid syndrome in this context.

Question 49

Which lipoprotein is responsible for transporting dietary triglycerides from the intestines to tissues?

Accepted Answer

Chylomicrons — Chylomicrons are the largest lipoproteins and are synthesized in the intestinal cells (enterocytes). They are responsible for the absorption and transport of dietary lipids, primarily triglycerides and cholesterol, from the small intestine into the lymphatic system and then into the bloodstream to be delivered to peripheral tissues.

Question 50

What is the primary function of HDL cholesterol?

Accepted Answer

Transporting cholesterol from peripheral tissues back to the liver — High-density lipoprotein (HDL) cholesterol is often referred to as 'good' cholesterol because it plays a crucial role in reverse cholesterol transport. It picks up excess cholesterol from peripheral tissues (like artery walls) and transports it back to the liver for excretion or recycling.

Weekly Pathology Exam - July 10, 2026 (Section A: MCQs)

Questions, Answers & Explanations