A 45-year-old Caucasian man is given nitroglycerin for the management of his stable angina. Nitroglycerin given for the rapid relief of acute angina would most likely be given through what route of administration?
Q432
A 28-year-old man comes to his general practitioner for a regular checkup. He has had trouble breathing lately with coughing, shortness of breath, and wheezing. Problems first started when he went running (outside), but he is also observing the problems when taking a light walk or resting. As a child, he suffered from atopic dermatitis, just like his father and sister. He also has a history of hay fever. What is the most likely cause of his symptoms?
Q433
A 66-year-old gentleman presents to a new primary care physician to establish care after a recent relocation. His past medical history is significant for gout, erectile dysfunction, osteoarthritis of bilateral knees, mitral stenosis, and diabetic peripheral neuropathy. He denies any past surgeries along with the use of any tobacco, alcohol, or illicit drugs. He has no known drug allergies and cannot remember the names of the medications he is taking for his medical problems. He states that he has recently been experiencing chest pain with strenuous activities. What part of the patient's medical history must be further probed before starting him on a nitrate for chest pain?
Q434
A 7-year-old boy with asthma is brought to the emergency department because of a 1-day history of shortness of breath and cough. Current medications are inhaled albuterol and beclomethasone. His temperature is 37°C (98.6°F) and respirations are 24/min. Pulmonary examination shows bilateral expiratory wheezing. Serum studies show increased concentrations of interleukin-5. Which of the following is the most likely effect of the observed laboratory finding in this patient?
Q435
A 62-year-old man comes to the physician because of tremors in both hands for the past few months. He has had difficulty buttoning his shirts and holding a cup of coffee without spilling its content. He has noticed that his symptoms improve after a glass of whiskey. His maternal uncle began to develop similar symptoms around the same age. He has bronchial asthma controlled with albuterol and fluticasone. Examination shows a low-amplitude tremor bilaterally when the arms are outstretched that worsens during the finger-to-nose test. Which of the following is the most appropriate pharmacotherapy in this patient?
Q436
A 28-year-old woman presents to a psychiatrist with a 10-year history of unexplained anxiety symptoms. To date, she has not visited any psychiatrist, because she believes that she should not take medicines to change her emotions or thoughts. However, after explaining the nature of her disorder, the psychiatrist prescribes daily alprazolam. When she comes for her first follow-up, she reports excellent relief from her symptoms without any side-effects. The psychiatrist encourages her to continue her medication for the next 3 months and then return for a follow-up visit. After 3 months, she tells her psychiatrist that she has been experiencing excessive sedation and drowsiness over the last few weeks. The psychiatrist finds that she is taking alprazolam in the correct dosage, and she is not taking any other medication that causes sedation. Upon asking her about any recent changes in her lifestyle, she mentions that for the last 2 months, she has made a diet change. The psychiatrist tells her that diet change may be the reason why she is experiencing excessive sedation and drowsiness. Which of the following is the most likely diet change the psychiatrist is talking about?
Q437
A 45-year-old man comes to the physician because of a 3-month history of recurrent headaches. The headaches are of a dull, nonpulsating quality. The patient denies nausea, vomiting, photophobia, or phonophobia. Neurologic examination shows no abnormalities. The physician prescribes a drug that irreversibly inhibits cyclooxygenase-1 and cyclooxygenase-2 by covalent acetylation. Which of the following medications was most likely prescribed by the physician?
Q438
A 67-year-old woman is admitted to the hospital because of a 2-day history of fever, headache, jaw pain, and decreased vision in the right eye. Her erythrocyte sedimentation rate is 84 mm per hour. Treatment with methylprednisolone is initiated but her symptoms do not improve. The physician recommends the administration of a new drug. Three days after treatment with the new drug is started, visual acuity in the right eye increases. The beneficial effect of this drug is most likely due to inhibition of which of the following molecules?
Q439
A 43-year-old woman presents to her primary care provider for follow-up of her glucose levels. At her last visit 3 months ago, her fasting serum glucose was 128 mg/dl. At that time, she was instructed to follow a weight loss regimen consisting of diet and exercise. Her family history is notable for a myocardial infarction in her father and type II diabetes mellitus in her mother. She does not smoke and drinks 2-3 glasses of wine per week. Her temperature is 99°F (37.2°C), blood pressure is 131/78 mmHg, pulse is 80/min, and respirations are 17/min. Her BMI is 31 kg/m^2. On exam, she is well-appearing and appropriately interactive. Today, despite attempting to make the appropriate lifestyle changes, a repeat fasting serum glucose is 133 mg/dl. The patient is prescribed the first-line oral pharmacologic agent for her condition. Which of the following is the correct mechanism of action of this medication?
Q440
A previously healthy 52-year-old man comes to the physician because of a 4-month history of recurrent abdominal pain, foul-smelling, greasy stools, and a 5-kg (11-lb) weight loss despite no change in appetite. Physical examination shows pain on palpation of the right upper quadrant. His fasting serum glucose concentration is 186 mg/dL. Abdominal ultrasound shows multiple round, echogenic foci within the gallbladder lumen with prominent posterior acoustic shadowing. The serum concentration of which of the following substances is most likely to be increased in this patient?
Autonomic/CV Drugs US Medical PG Practice Questions and MCQs
Question 431: A 45-year-old Caucasian man is given nitroglycerin for the management of his stable angina. Nitroglycerin given for the rapid relief of acute angina would most likely be given through what route of administration?
A. Subcutaneous injection
B. Intramuscular injection
C. Intravenous injection
D. Sublingual (Correct Answer)
E. Oral
Explanation: ***Sublingual***
- **Sublingual** administration provides rapid absorption into the bloodstream through the oral mucosa, bypassing first-pass metabolism, which is crucial for quick relief of acute angina.
- This route allows the medication to exert its vasodilatory effects within 1-3 minutes, alleviating chest pain efficiently.
- It is the **standard of care** for outpatient management of acute angina episodes due to ease of self-administration.
*Subcutaneous injection*
- **Subcutaneous injection** has a slower onset of action compared to sublingual administration, making it unsuitable for rapid relief of acute angina.
- While it avoids first-pass metabolism, the absorption rate is not fast enough for emergency situations.
*Intramuscular injection*
- **Intramuscular injection** also has a relatively slower onset of action and is less predictable for rapid relief compared to sublingual routes.
- It is not a standard route for acute angina management due to the need for immediate action.
*Intravenous injection*
- **Intravenous administration** provides immediate systemic availability and is used for continuous infusion in unstable angina or acute coronary syndromes in hospital settings.
- However, it is **not practical for outpatient or self-administered rapid relief** due to the need for IV access, medical personnel, and monitoring.
- While highly effective in critical care, it is not the route for typical acute angina episodes outside the hospital.
*Oral*
- **Oral administration** undergoes significant **first-pass metabolism** in the liver, which delays the onset of action and reduces bioavailability, rendering it ineffective for rapid relief of acute angina.
- The delayed absorption (typically 30-60 minutes) makes it impractical for emergency situations where immediate vasodilation is needed.
- Oral nitrates are used for prophylaxis, not acute relief.
Question 432: A 28-year-old man comes to his general practitioner for a regular checkup. He has had trouble breathing lately with coughing, shortness of breath, and wheezing. Problems first started when he went running (outside), but he is also observing the problems when taking a light walk or resting. As a child, he suffered from atopic dermatitis, just like his father and sister. He also has a history of hay fever. What is the most likely cause of his symptoms?
A. Smoking
B. Chronic obstructive pulmonary disease
C. Type I hypersensitivity (Correct Answer)
D. Type IV hypersensitivity
E. Exercise
Explanation: ***Type I hypersensitivity***
- The patient's presentation with **coughing, shortness of breath, and wheezing** suggests **bronchial asthma**, which is a classic manifestation of **Type I hypersensitivity** (allergic reaction).
- The history of **atopic dermatitis** (eczema) and **hay fever** indicates an **atopic diathesis**, which is a strong predisposing factor for allergic asthma. This forms the **atopic triad**.
*Smoking*
- While smoking can cause respiratory symptoms like coughing and shortness of breath, it typically does not cause acute wheezing that improves with rest in a young, otherwise healthy individual.
- The patient's personal history of atopic dermatitis and hay fever, and running in the family does not suggest smoking.
*Chronic obstructive pulmonary disease*
- **COPD** usually develops in older individuals, often with a history of significant smoking or environmental exposure, and is characterized by **progressive, non-reversible airflow limitation**.
- The patient's young age and history of atopic conditions make COPD a less likely diagnosis compared to asthma.
*Type IV hypersensitivity*
- **Type IV hypersensitivity**, or **delayed-type hypersensitivity**, typically manifests as contact dermatitis (e.g., poison ivy) or granulomatous reactions, which are T-cell mediated and develop over 24-72 hours.
- It does not cause acute respiratory symptoms like wheezing, nor is it linked to atopic conditions such as hay fever and asthma.
*Exercise*
- Exercise can trigger **exercise-induced bronchoconstriction (asthma)**, which presents as shortness of breath and wheezing during or after physical activity.
- However, the patient also experiences symptoms during light walks or at rest, and has a strong atopic history, indicating that exercise is a trigger for underlying asthma (Type I hypersensitivity) rather than the sole cause of symptoms.
Question 433: A 66-year-old gentleman presents to a new primary care physician to establish care after a recent relocation. His past medical history is significant for gout, erectile dysfunction, osteoarthritis of bilateral knees, mitral stenosis, and diabetic peripheral neuropathy. He denies any past surgeries along with the use of any tobacco, alcohol, or illicit drugs. He has no known drug allergies and cannot remember the names of the medications he is taking for his medical problems. He states that he has recently been experiencing chest pain with strenuous activities. What part of the patient's medical history must be further probed before starting him on a nitrate for chest pain?
A. Erectile dysfunction (Correct Answer)
B. Diabetic peripheral neuropathy
C. Gout
D. Arthritis
E. Mitral stenosis
Explanation: ***Erectile dysfunction***
- Patients often take **phosphodiesterase-5 (PDE5) inhibitors** (e.g., sildenafil, tadalafil) for erectile dysfunction, which are absolutely contraindicated with nitrates.
- **Co-administration** can lead to a severe and potentially fatal drop in blood pressure due to enhanced vasodilation.
*Diabetic peripheral neuropathy*
- While important for overall health assessment, **diabetic peripheral neuropathy** does not directly contraindicate the use of nitrates for chest pain.
- It might influence medication choices if a patient has orthostatic hypotension, but not a direct contraindication.
*Gout*
- **Gout** is a joint condition and has no direct contraindication with nitrate use.
- Medications for gout, such as allopurinol or colchicine, do not interact adversely with nitrates.
*Arthritis*
- **Arthritis** (including osteoarthritis mentioned) is a musculoskeletal condition and does not contraindicate nitrate therapy.
- Pain management for arthritis does not typically involve drugs that interact dangerously with nitrates.
*Mitral stenosis*
- While **mitral stenosis** can affect cardiac function and hemodynamics, it is generally not an absolute contraindication to nitrate use.
- Nitrates can even be used cautiously in **mitral stenosis** to manage angina, though their use requires careful monitoring of preload.
Question 434: A 7-year-old boy with asthma is brought to the emergency department because of a 1-day history of shortness of breath and cough. Current medications are inhaled albuterol and beclomethasone. His temperature is 37°C (98.6°F) and respirations are 24/min. Pulmonary examination shows bilateral expiratory wheezing. Serum studies show increased concentrations of interleukin-5. Which of the following is the most likely effect of the observed laboratory finding in this patient?
A. Suppression of MHC class II expression
B. Recruitment of eosinophils (Correct Answer)
C. Induction of immunoglobulin class switching to IgE
D. Differentiation of bone marrow stem cells
E. Secretion of acute phase reactants
Explanation: ***Recruitment of eosinophils***
- **Interleukin-5 (IL-5)** is a key cytokine primarily responsible for the **differentiation, maturation, and activation of eosinophils**.
- In asthma, an increase in IL-5 leads to the **recruitment of eosinophils** to the airways, contributing to inflammation and bronchoconstriction.
*Suppression of MHC class II expression*
- **MHC class II expression** is mainly modulated by other cytokines such as **IFN-γ** (upregulation) and **IL-10** (downregulation), not IL-5.
- IL-5's primary role is in **eosinophil biology**, not in antigen presentation regulation.
*Induction of immunoglobulin class switching to IgE*
- **Immunoglobulin class switching to IgE** is primarily driven by **IL-4** and **IL-13**, in synergy with **CD40-CD40L interactions**.
- While IgE is involved in allergic asthma, IL-5 directly influences **eosinophils**, not IgE class switching.
*Differentiation of bone marrow stem cells*
- The **differentiation of various bone marrow stem cells** into specific lineages is a complex process involving a wide array of **colony-stimulating factors** and interleukins (e.g., GM-CSF, G-CSF, M-CSF, IL-3).
- While IL-5 promotes eosinophil development, it is not broadly responsible for the differentiation of all bone marrow stem cells.
*Secretion of acute phase reactants*
- **Acute phase reactants** (e.g., CRP, ESR) are primarily secreted by the liver in response to IL-1, IL-6, and TNF-α during **acute inflammation**.
- IL-5 is not a primary inducer of acute phase reactant secretion.
Question 435: A 62-year-old man comes to the physician because of tremors in both hands for the past few months. He has had difficulty buttoning his shirts and holding a cup of coffee without spilling its content. He has noticed that his symptoms improve after a glass of whiskey. His maternal uncle began to develop similar symptoms around the same age. He has bronchial asthma controlled with albuterol and fluticasone. Examination shows a low-amplitude tremor bilaterally when the arms are outstretched that worsens during the finger-to-nose test. Which of the following is the most appropriate pharmacotherapy in this patient?
A. Levodopa
B. Propranolol
C. Valproic acid
D. Alprazolam
E. Primidone (Correct Answer)
Explanation: ***Primidone***
- The patient exhibits symptoms consistent with **essential tremor**, characterized by an **action tremor** that improves with alcohol and a family history. Primidone is a first-line agent, and an **anticonvulsant** used to treat essential tremor.
- While **propranolol** is also a first-line treatment, it is contraindicated in this patient due to his history of **bronchial asthma**.
*Levodopa*
- **Levodopa** is the primary treatment for **Parkinson's disease**, which typically presents with a **resting tremor**, bradykinesia, rigidity, and postural instability.
- The patient's tremor is an **action tremor**, not a resting tremor, and he lacks other parkinsonian features.
*Propranolol*
- **Propranolol** is a first-line treatment for essential tremor, effective in reducing tremor severity.
- However, it is a **non-selective beta-blocker** and is contraindicated in patients with **asthma** due to the risk of bronchospasm.
*Valproic acid*
- **Valproic acid** is primarily an antiepileptic drug and mood stabilizer, and is not a first-line treatment for essential tremor.
- Its use for tremor is generally reserved for other types of tremors or as an **adjunctive therapy** in refractory cases, not as a primary treatment for essential tremor.
*Alprazolam*
- **Alprazolam** is a benzodiazepine used to treat anxiety and panic disorders, and can sometimes help with **anxiety-potentiated tremors**.
- While it may temporarily reduce tremor due to its sedative effects, it is not a primary or long-term treatment for essential tremor due to issues like **tolerance, dependence, and sedation**.
Question 436: A 28-year-old woman presents to a psychiatrist with a 10-year history of unexplained anxiety symptoms. To date, she has not visited any psychiatrist, because she believes that she should not take medicines to change her emotions or thoughts. However, after explaining the nature of her disorder, the psychiatrist prescribes daily alprazolam. When she comes for her first follow-up, she reports excellent relief from her symptoms without any side-effects. The psychiatrist encourages her to continue her medication for the next 3 months and then return for a follow-up visit. After 3 months, she tells her psychiatrist that she has been experiencing excessive sedation and drowsiness over the last few weeks. The psychiatrist finds that she is taking alprazolam in the correct dosage, and she is not taking any other medication that causes sedation. Upon asking her about any recent changes in her lifestyle, she mentions that for the last 2 months, she has made a diet change. The psychiatrist tells her that diet change may be the reason why she is experiencing excessive sedation and drowsiness. Which of the following is the most likely diet change the psychiatrist is talking about?
A. Daily consumption of tomatoes
B. Daily consumption of St. John's wort
C. Daily consumption of cruciferous vegetables
D. Daily consumption of grapefruit juice (Correct Answer)
E. Daily consumption of charcoal-broiled foods
Explanation: ***Daily consumption of grapefruit juice***
- **Grapefruit juice** is a potent inhibitor of the **CYP3A4 enzyme**, which is responsible for the metabolism of **alprazolam**.
- Inhibition of CYP3A4 leads to **increased plasma concentrations of alprazolam**, enhancing its sedative effects and causing drowsiness.
*Daily consumption of tomatoes*
- **Tomatoes** do not significantly interact with the metabolism of **alprazolam** or other benzodiazepines.
- They are a healthy food item with no known common drug interactions relevant to alprazolam's side effects.
*Daily consumption of St. John's wort*
- **St. John's wort** is a known **CYP3A4 inducer**, meaning it would *decrease* alprazolam levels, potentially leading to reduced efficacy.
- It would not cause increased sedation or drowsiness due to higher alprazolam concentrations.
*Daily consumption of cruciferous vegetables*
- **Cruciferous vegetables** (e.g., broccoli, cabbage) can induce certain CYP enzymes but generally do not significantly interfere with **alprazolam metabolism** to cause increased sedation.
- Their effects on drug metabolism are usually less pronounced or specific to other enzyme systems.
*Daily consumption of charcoal-broiled foods*
- **Charcoal-broiled foods** can induce **CYP1A2 enzymes**, but **alprazolam** is primarily metabolized by CYP3A4.
- Therefore, this dietary change is unlikely to significantly impact alprazolam metabolism or lead to increased sedation.
Question 437: A 45-year-old man comes to the physician because of a 3-month history of recurrent headaches. The headaches are of a dull, nonpulsating quality. The patient denies nausea, vomiting, photophobia, or phonophobia. Neurologic examination shows no abnormalities. The physician prescribes a drug that irreversibly inhibits cyclooxygenase-1 and cyclooxygenase-2 by covalent acetylation. Which of the following medications was most likely prescribed by the physician?
A. Prednisolone
B. Indomethacin
C. Aspirin (Correct Answer)
D. Carbamazepine
E. Celecoxib
Explanation: **Aspirin**
- Aspirin is a non-steroidal anti-inflammatory drug (**NSAID**) that **covalently acetylates** and irreversibly inhibits both **COX-1** and **COX-2** enzymes.
- The described mechanism of action (irreversible inhibition of COX-1 and COX-2 by covalent acetylation) is characteristic of aspirin.
*Prednisolone*
- **Prednisolone** is a corticosteroid, which inhibits inflammation by affecting **gene transcription** and protein synthesis, rather than directly inhibiting cyclooxygenase enzymes.
- Its mechanism involves suppressing the immune system and reducing inflammatory mediators, distinct from COX inhibition.
*Indomethacin*
- **Indomethacin** is a non-selective NSAID that reversibly inhibits COX-1 and COX-2.
- It does not involve covalent acetylation for its inhibitory action, unlike aspirin.
*Carbamazepine*
- **Carbamazepine** is an anticonvulsant medication primarily used for epilepsy and trigeminal neuralgia.
- Its mechanism of action involves blocking **voltage-gated sodium channels**, thereby stabilizing neuronal membranes and reducing seizure propagation.
*Celecoxib*
- **Celecoxib** is a selective **COX-2 inhibitor**, meaning it primarily targets COX-2 enzymes while sparing COX-1.
- Furthermore, it is a reversible inhibitor, not an irreversible one through covalent acetylation.
Question 438: A 67-year-old woman is admitted to the hospital because of a 2-day history of fever, headache, jaw pain, and decreased vision in the right eye. Her erythrocyte sedimentation rate is 84 mm per hour. Treatment with methylprednisolone is initiated but her symptoms do not improve. The physician recommends the administration of a new drug. Three days after treatment with the new drug is started, visual acuity in the right eye increases. The beneficial effect of this drug is most likely due to inhibition of which of the following molecules?
A. Leukotriene D4
B. Interleukin-4
C. Complement component 5
D. Interleukin-6 (Correct Answer)
E. Thromboxane A2
Explanation: ***Interleukin-6***
- The patient's symptoms (fever, headache, jaw pain, decreased vision, elevated ESR) are classic for **giant cell arteritis (GCA)**. GCA involves transmural inflammation of medium to large arteries, often affecting the temporal artery and ophthalmic artery.
- **Tocilizumab**, a monoclonal antibody that targets the **IL-6 receptor**, is an approved treatment for GCA, especially in cases unresponsive to corticosteroids or for steroid-sparing effects. Its efficacy in improving vision and reducing inflammation supports its action on IL-6.
*Leukotriene D4*
- **Leukotriene D4** is a potent bronchoconstrictor and mediator in allergic and asthmatic responses.
- Inhibitors of leukotriene D4, such as montelukast, are used to treat **asthma** and **allergic rhinitis**, not vasculitis like GCA.
*Interleukin-4*
- **Interleukin-4** is a key cytokine in the **Th2 immune response**, promoting B-cell activation, **IgE production**, and allergic inflammation.
- Drugs targeting IL-4 (or its receptor) are used in conditions like **atopic dermatitis** and **asthma**, not GCA, which is primarily a Th1-mediated inflammatory disease.
*Complement component 5*
- **Complement component 5 (C5)** is a central molecule in the **complement cascade**, playing a role in inflammation and cell lysis.
- While the complement system can be involved in various inflammatory conditions, specific C5 inhibition is primarily seen with drugs like **Eculizumab** for paroxysmal nocturnal hemoglobinuria or atypical hemolytic uremic syndrome, which are distinct from GCA.
*Thromboxane A2*
- **Thromboxane A2** is a potent vasoconstrictor and platelet aggregator, primarily produced by platelets.
- Its inhibition, typically by **aspirin**, is used for **antiplatelet effects** in cardiovascular disease and stroke prevention, not for the direct treatment of large vessel vasculitis or to rapidly resolve visual loss in GCA.
Question 439: A 43-year-old woman presents to her primary care provider for follow-up of her glucose levels. At her last visit 3 months ago, her fasting serum glucose was 128 mg/dl. At that time, she was instructed to follow a weight loss regimen consisting of diet and exercise. Her family history is notable for a myocardial infarction in her father and type II diabetes mellitus in her mother. She does not smoke and drinks 2-3 glasses of wine per week. Her temperature is 99°F (37.2°C), blood pressure is 131/78 mmHg, pulse is 80/min, and respirations are 17/min. Her BMI is 31 kg/m^2. On exam, she is well-appearing and appropriately interactive. Today, despite attempting to make the appropriate lifestyle changes, a repeat fasting serum glucose is 133 mg/dl. The patient is prescribed the first-line oral pharmacologic agent for her condition. Which of the following is the correct mechanism of action of this medication?
A. Inhibition of hepatic gluconeogenesis (Correct Answer)
B. Activation of peroxisome proliferator-activating receptors
C. Inhibition of the sodium-glucose cotransporter
D. Closure of potassium channels in pancreatic beta cells
E. Inhibition of alpha-glucosidase in the intestinal brush border
Explanation: ***Inhibition of hepatic gluconeogenesis***
- This patient's fasting glucose levels (128 mg/dL and 133 mg/dL on repeat testing) meet the diagnostic criteria for **type 2 diabetes mellitus** (fasting glucose ≥126 mg/dL on two separate occasions). Given her elevated BMI, family history, and persistent hyperglycemia despite lifestyle modifications, the most appropriate first-line pharmacologic agent is **metformin**.
- **Metformin** primarily acts by **decreasing hepatic glucose production**, mainly through the inhibition of gluconeogenesis, and also improves insulin sensitivity in peripheral tissues.
*Activation of peroxisome proliferator-activating receptors*
- This is the mechanism of action for **thiazolidinediones (TZDs)**, such as pioglitazone and rosiglitazone.
- While TZDs improve insulin sensitivity, they are generally **not considered first-line agents** due to potential side effects like weight gain, edema, and cardiovascular risks.
*Inhibition of the sodium-glucose cotransporter*
- This describes the mechanism of action for **SGLT2 inhibitors**, such as empagliflozin and canagliflozin.
- SGLT2 inhibitors block glucose reabsorption in the kidneys, leading to **glucose excretion in the urine**, and are typically used as second-line therapy or in patients with cardiovascular disease or chronic kidney disease.
*Closure of potassium channels in pancreatic beta cells*
- This is the mechanism of action for **sulfonylureas**, such as glipizide and glyburide, and **meglitinides**.
- These medications **stimulate insulin secretion** from pancreatic beta cells, but they carry a higher risk of hypoglycemia and weight gain compared to metformin.
*Inhibition of alpha-glucosidase in the intestinal brush border*
- This is the mechanism of action for **alpha-glucosidase inhibitors**, such as acarbose and miglitol.
- These drugs **delay carbohydrate absorption** in the gut, which can help reduce postprandial glucose levels, but they are not typically considered first-line for overall glucose control due to gastrointestinal side effects.
Question 440: A previously healthy 52-year-old man comes to the physician because of a 4-month history of recurrent abdominal pain, foul-smelling, greasy stools, and a 5-kg (11-lb) weight loss despite no change in appetite. Physical examination shows pain on palpation of the right upper quadrant. His fasting serum glucose concentration is 186 mg/dL. Abdominal ultrasound shows multiple round, echogenic foci within the gallbladder lumen with prominent posterior acoustic shadowing. The serum concentration of which of the following substances is most likely to be increased in this patient?
A. Glucagon
B. Serotonin
C. Insulin
D. Somatostatin (Correct Answer)
E. Vasoactive intestinal peptide
Explanation: ***Somatostatin***
- Elevated **somatostatin** levels can inhibit the release of various gastrointestinal hormones and enzymes, leading to malabsorption, **steatorrhea (foul-smelling, greasy stools)**, and **weight loss**, as seen in this patient.
- The abdominal pain, gallstones (echogenic foci with posterior acoustic shadowing), and elevated fasting glucose suggest a possible **somatostatinoma**, a rare neuroendocrine tumor producing somatostatin.
*Glucagon*
- **Glucagon** primarily increases blood glucose, which is elevated here, but its excess typically presents with a characteristic **necrolytic migratory erythema** and severe weight loss, not malabsorption as the primary GI symptom.
- While high blood glucose is present, malabsorption symptoms and gallstones are not typical features of a glucagonoma.
*Insulin*
- **Insulin** lowers blood glucose, so an increased concentration would lead to **hypoglycemia**, not the hyperglycemia (186 mg/dL) observed in this patient.
- Symptoms of insulin excess (e.g., insulinoma) would include neuroglycopenic symptoms and weight gain, not malabsorption and weight loss.
*Serotonin*
- Increased **serotonin** levels are associated with **carcinoid syndrome**, which typically presents with flushing, diarrhea, bronchospasm, and valvular heart disease.
- Although diarrhea can be a symptom, the specific features of malabsorption, recurrent abdominal pain, gallstones, and hyperglycemia do not align well with carcinoid syndrome.
*Vasoactive intestinal peptide*
- Elevated **vasoactive intestinal peptide (VIP)**, as in **VIPoma**, causes severe watery diarrhea, hypokalemia, and achlorhydria (WDHA syndrome).
- While weight loss can occur due to fluid loss, the presence of steatorrhea, gallstones, and hyperglycemia makes VIPoma a less likely diagnosis.