A 25-year-old man presents to the emergency department with pain in his leg. He states that the pain was sudden and that his leg feels very tender. This has happened before, but symptoms resolved a few days later with acetaminophen. His temperature is 98.5°F (36.9°C), blood pressure is 129/88 mmHg, pulse is 90/min, respirations are 12/min, and oxygen saturation is 98% on room air. Physical exam reveals clear breath sounds bilaterally and a normal S1 and S2. The patient’s right leg is red, inflamed, and tender to palpation inferior to the popliteal fossa. Which of the following is the best treatment for this patient?
Q642
A 42-year-old man is brought in to the emergency department by his daughter. She reports that her father drank heavily for the last 16 years, but he stopped 4 days ago after he decided to quit drinking on his birthday. She also reports that he has been talking about seeing cats running in his room since this morning, although there were no cats. There is no history of any known medical problems or any other substance use. On physical examination, his temperature is 38.4ºC (101.2ºF), heart rate is 116/min, blood pressure is 160/94 mm Hg, and respiratory rate is 22/min. He is severely agitated and is not oriented to his name, time, or place. On physical examination, profuse perspiration and tremors are present. Which of the following best describes the pathophysiologic mechanism underlying his condition?
Q643
A 47-year-old African-American woman presents to her primary care physician for a general checkup appointment. She works as a middle school teacher and has a 25 pack-year smoking history. She has a body mass index (BMI) of 22 kg/m^2 and is a vegetarian. Her last menstrual period was 1 week ago. Her current medications include oral contraceptive pills. Which of the following is a risk factor for osteoporosis in this patient?
Q644
A 33-year-old man comes to the emergency department because of a pounding headache for the past 3 hours. The pain is 8 out of 10 in intensity, does not radiate, and is not relieved by ibuprofen. He also has associated dizziness, blurring of vision, and palpitations. He has had similar episodes over the last 6 months but none this severe. He has not had fever, weight change, or loss of appetite. He underwent an appendectomy at the age of 18. His father died of renal cancer. He is diaphoretic. His temperature is 36.8°C (98.4°F), pulse is 112/min, and blood pressure is 220/130 mm Hg. Physical examination shows no abnormalities. Laboratory studies show:
Hemoglobin 14.8 g/dL
Leukocyte count 9600/mm3
Platelet count 345,000/mm3
Serum
Glucose 112 mg/dL
Na+ 137 mEq/L
K+ 4.2 mEq/L
Cl- 105 mEq/L
Creatinine 1.0 mg/dL
Urine dipstick shows no abnormalities. Which of the following findings on imaging is the most likely explanation for this patient's symptoms?
Q645
A 25-year-old man presents to the clinic with a complaint of lightheadedness when standing up from his bed in the morning and then from his chair at work. He has had similar complaints for many months, and the symptoms have not improved despite drinking lots of fluids, eating regular meals, and taking daily multivitamin. His daily routine is disturbed as he finds himself getting up very slowly to avoid the problem. This has created some awkward situations at his workplace and in social settings. His blood pressure while seated is 120/80 mm Hg, and upon standing it falls to 100/68 mm Hg. The physical examination is unremarkable except for a strong odor suggestive of marijuana use. The patient denies drug use and insists the odor is due to his roommate who smokes marijuana for medical purposes. No pallor or signs of dehydration are seen. The lab results are as follows:
Serum Glucose 90 mg/dL
Sodium 140 mEq/L
Potassium 4.1 mEq/L
Chloride 100 mEq/L
Serum Creatinine 0.8 mg/dL
Blood Urea Nitrogen 9 mg/dL
Hemoglobin (Hb) Concentration 15.3 g/dL
Mean Corpuscular Volume (MCV) 83 fl
Reticulocyte count 0.5%
Erythrocyte count 5.3 million/mm3
Platelet count 200,000/mm3
The ECG shows no abnormal finding. Which of the following could alleviate this patient’s symptoms?
Q646
A 7-year-old boy with asthma is brought to the physician because of a 1-month history of worsening shortness of breath and cough. The mother reports that the shortness of breath usually occurs when he is exercising with his older brother. His only medication is an albuterol inhaler that is taken as needed. The physician considers adding zafirlukast to his drug regimen. Which of the following is the most likely mechanism of action of this drug?
Q647
A 38-year-old man comes to the physician because of a 2-year-history of cough and progressively worsening breathlessness. He has smoked 1 pack of cigarettes daily for the past 10 years. Physical examination shows contraction of the anterior scalene and sternocleidomastoid muscles during inspiration. An x-ray of the chest shows flattening of the diaphragm and increased radiolucency in the lower lung fields. Further analysis shows increased activity of an isoform of elastase that is normally inhibited by alpha-1-antitrypsin. The cells that produce this isoform of elastase were most likely stimulated to enter the site of inflammation by which of the following substances?
Q648
A 10-year-old boy presents to the emergency department with sudden shortness of breath. He was playing in the school garden and suddenly started to complain of abdominal pain. He then vomited a few times. An hour later in the hospital, he slowly developed a rash on his chest, arms, and legs. His breathing became faster with audible wheezing. On physical examination, his vital signs are as follows: the temperature is 37.0°C (98.6°F), the blood pressure is 100/60 mm Hg, the pulse is 130/min, and the respiratory rate is 25/min. A rash is on his right arm, as shown in the image. After being administered appropriate treatment, the boy improves significantly, and he is able to breathe comfortably. Which of the following is the best marker that could be measured in the serum of this boy to help establish a definitive diagnosis?
Q649
A 17-year-old high school student is brought to the emergency department because of irritability and rapid breathing. He appears agitated and is diaphoretic. His temperature is 38.3°C (101°F), pulse is 129/min, respirations are 28/min, and blood pressure is 158/95 mmHg. His pupils are dilated. An ECG shows sinus tachycardia. Which of the following substances is used to make the drug this patient has most likely taken?
Q650
A 60-year-old man is brought to the emergency department because of a 30-minute history of dizziness and shortness of breath. After establishing the diagnosis, treatment with a drug is administered. Shortly after administration, the patient develops severe left eye pain and decreased vision of the left eye, along with nausea and vomiting. Ophthalmologic examination shows a fixed, mid-dilated pupil and a narrowed anterior chamber of the left eye. The patient was most likely treated for which of the following conditions?
Autonomic/CV Drugs US Medical PG Practice Questions and MCQs
Question 641: A 25-year-old man presents to the emergency department with pain in his leg. He states that the pain was sudden and that his leg feels very tender. This has happened before, but symptoms resolved a few days later with acetaminophen. His temperature is 98.5°F (36.9°C), blood pressure is 129/88 mmHg, pulse is 90/min, respirations are 12/min, and oxygen saturation is 98% on room air. Physical exam reveals clear breath sounds bilaterally and a normal S1 and S2. The patient’s right leg is red, inflamed, and tender to palpation inferior to the popliteal fossa. Which of the following is the best treatment for this patient?
A. Heparin (Correct Answer)
B. Aspirin
C. Ibuprofen and rest
D. Clindamycin
E. Warfarin
Explanation: ***Heparin***
- The sudden onset of leg pain, tenderness, and inflammation, especially with a history of recurrent episodes, is highly suggestive of a **deep vein thrombosis (DVT)**. The location inferior to the popliteal fossa is a common site for calf vein DVTs.
- **Heparin** (either unfractionated or low molecular weight) is the first-line treatment for acute DVT to prevent clot propagation, pulmonary embolism, and post-thrombotic syndrome.
*Aspirin*
- **Aspirin** is an antiplatelet agent used for arterial thrombosis and cardiovascular event prevention, not effective for treating acute venous thromboembolism like DVT.
- Its mechanism primarily involves inhibiting cyclooxygenase to reduce thromboxane A2, which is less relevant in the coagulation cascade implicated in DVT.
*Ibuprofen and rest*
- **Ibuprofen** is an NSAID that can reduce pain and inflammation but does not address the underlying **thrombotic process** and will not prevent complications like pulmonary embolism.
- While rest might alleviate discomfort, it is not a primary treatment for DVT and prolonged immobility can actually worsen venous stasis.
*Clindamycin*
- **Clindamycin** is an antibiotic used to treat bacterial infections; it has no role in the management of DVT, which is a vascular condition.
- There are no signs of infection in the patient's presentation that would warrant antibiotic therapy.
*Warfarin*
- **Warfarin** is an oral anticoagulant used for long-term management of DVT and other thrombotic conditions, but it has a **delayed onset of action** (several days) due to its mechanism of inhibiting vitamin K-dependent clotting factors.
- It is typically initiated concurrently with a rapid-acting anticoagulant like heparin, which provides immediate anticoagulation until warfarin reaches therapeutic levels.
Question 642: A 42-year-old man is brought in to the emergency department by his daughter. She reports that her father drank heavily for the last 16 years, but he stopped 4 days ago after he decided to quit drinking on his birthday. She also reports that he has been talking about seeing cats running in his room since this morning, although there were no cats. There is no history of any known medical problems or any other substance use. On physical examination, his temperature is 38.4ºC (101.2ºF), heart rate is 116/min, blood pressure is 160/94 mm Hg, and respiratory rate is 22/min. He is severely agitated and is not oriented to his name, time, or place. On physical examination, profuse perspiration and tremors are present. Which of the following best describes the pathophysiologic mechanism underlying his condition?
A. Increased influx of chloride ions
B. Increased inhibition of norepinephrine
C. Functional increase in GABA
D. Increased activity of NMDA receptors (Correct Answer)
E. Increased inhibition of glutamate
Explanation: ***Increased activity of NMDA receptors***
- Chronic alcohol use leads to **downregulation of GABA receptors** and **upregulation of NMDA receptors** to compensate for alcohol's inhibitory effects.
- When alcohol is withdrawn, the unopposed upregulation of NMDA receptors (and decreased GABA activity) causes a state of **neuronal hyperexcitability**, leading to symptoms like agitation, hallucinations, and autonomic hyperactivity seen in **delirium tremens**.
*Increased influx of chloride ions*
- This describes the mechanism of action of **GABA-A agonists** (like benzodiazepines), which enhance GABA's inhibitory effects by increasing chloride influx and hyperpolarizing neurons.
- In alcohol withdrawal, there is a **functional decrease in GABAergic activity**, not an increase in chloride ion influx.
*Increased inhibition of norepinephrine*
- **Norepinephrine** is a neurotransmitter associated with wakefulness, alertness, and autonomic responses; increased activity is seen in alcohol withdrawal, contributing to sympathetic overdrive.
- Increased inhibition of norepinephrine would lead to sedation and reduced autonomic activity, which is the opposite of the patient's presentation.
*Functional increase in GABA*
- **GABA** (gamma-aminobutyric acid) is the primary inhibitory neurotransmitter in the brain; alcohol enhances GABAergic activity.
- In alcohol withdrawal, there is a **functional decrease in GABAergic activity**, contributing to neuronal hyperexcitability and withdrawal symptoms.
*Increased inhibition of glutamate*
- **Glutamate** is the primary excitatory neurotransmitter, and its receptors (like NMDA) are implicated in alcohol withdrawal.
- Alcohol withdrawal is characterized by **increased excitatory activity**, including increased glutamate release and NMDA receptor activation, not increased inhibition of glutamate.
Question 643: A 47-year-old African-American woman presents to her primary care physician for a general checkup appointment. She works as a middle school teacher and has a 25 pack-year smoking history. She has a body mass index (BMI) of 22 kg/m^2 and is a vegetarian. Her last menstrual period was 1 week ago. Her current medications include oral contraceptive pills. Which of the following is a risk factor for osteoporosis in this patient?
A. Smoking history (Correct Answer)
B. Race
C. Estrogen therapy
D. Age
E. Body mass index
Explanation: ***Smoking history***
- **Smoking** is a well-established risk factor for osteoporosis due to its negative effects on bone density and **calcium absorption**.
- Smokers have lower bone density and increased fracture risk due to direct toxic effects on osteoblasts and accelerated estrogen metabolism.
*Race*
- **African-American women** typically have higher bone mineral density and a lower risk of osteoporosis compared to Caucasians and Asians.
- This patient's racial background is considered a protective factor, not a risk factor, for osteoporosis.
*Estrogen therapy*
- **Oral contraceptive pills** contain estrogen, which helps maintain bone density and is protective against osteoporosis.
- Estrogen deficiency, not estrogen therapy, is a risk factor for osteoporosis, especially after menopause.
*Age*
- While **advancing age** is a significant risk factor for osteoporosis, this patient is 47 years old and still having regular menstrual periods, indicating pre-menopausal status.
- The effects of age on bone density become more pronounced after menopause due to declining estrogen levels.
*Body mass index*
- A **BMI of 22 kg/m^2** is within the normal range, and higher BMI is generally associated with greater bone density due to increased weight bearing and higher estrogen levels in adipose tissue.
- Being underweight (low BMI) is a risk factor for osteoporosis, as it often correlates with poorer nutritional status and lower bone mass.
Question 644: A 33-year-old man comes to the emergency department because of a pounding headache for the past 3 hours. The pain is 8 out of 10 in intensity, does not radiate, and is not relieved by ibuprofen. He also has associated dizziness, blurring of vision, and palpitations. He has had similar episodes over the last 6 months but none this severe. He has not had fever, weight change, or loss of appetite. He underwent an appendectomy at the age of 18. His father died of renal cancer. He is diaphoretic. His temperature is 36.8°C (98.4°F), pulse is 112/min, and blood pressure is 220/130 mm Hg. Physical examination shows no abnormalities. Laboratory studies show:
Hemoglobin 14.8 g/dL
Leukocyte count 9600/mm3
Platelet count 345,000/mm3
Serum
Glucose 112 mg/dL
Na+ 137 mEq/L
K+ 4.2 mEq/L
Cl- 105 mEq/L
Creatinine 1.0 mg/dL
Urine dipstick shows no abnormalities. Which of the following findings on imaging is the most likely explanation for this patient's symptoms?
A. Paravertebral mass
B. Adrenal medullary mass (Correct Answer)
C. Intracranial hemorrhage
D. Renal cortical mass
E. Meningeal mass
Explanation: ***Adrenal medullary mass***
- The patient's symptoms (pounding headache, palpitations, diaphoresis, dizziness, blurred vision) along with severe **hypertension** (220/130 mmHg) and tachycardia (112/min) are classic for a **pheochromocytoma**, which is typically an adrenal medullary tumor.
- The episodic nature of the symptoms over 6 months and the patient's father dying of **renal cancer** (suggesting a potential familial syndrome like VHL or MEN2, which can include pheochromocytoma) further support this diagnosis.
*Paravertebral mass*
- While pheochromocytomas can sometimes be **extra-adrenal** (paragangliomas) and located in the paravertebral regions, an "adrenal medullary mass" is the most common and direct explanation for these symptoms.
- A paravertebral mass without the context of catecholamine excess would typically present with symptoms related to **compression** or local invasion, not systemic paroxysmal symptoms of hypertension, headache, and palpitations.
*Intracranial hemorrhage*
- An intracranial hemorrhage can cause severe headache and neurological symptoms, but it is less likely to cause a prolonged history of episodic symptoms with associated **palpitations and diaphoresis**.
- While severe hypertension can be a cause or consequence of hemorrhage, the constellation of symptoms strongly points towards **catecholamine excess**.
*Renal cortical mass*
- A renal cortical mass, such as a **renal cell carcinoma**, typically presents with hematuria, flank pain, or an abdominal mass.
- It usually does not cause paroxysmal headaches, palpitations, and severe, episodic hypertension unless it's an extremely rare instance of a renin-producing tumor, which wouldn't cause the other adrenergic symptoms.
*Meningeal mass*
- A meningeal mass (e.g., meningioma) typically causes symptoms related to **mass effect** on the brain or spinal cord, such as seizures, focal neurological deficits, or chronic headache.
- It would not explain the prominent **adrenergic symptoms** like palpitations and diaphoresis, or the severe, episodic hypertension.
Question 645: A 25-year-old man presents to the clinic with a complaint of lightheadedness when standing up from his bed in the morning and then from his chair at work. He has had similar complaints for many months, and the symptoms have not improved despite drinking lots of fluids, eating regular meals, and taking daily multivitamin. His daily routine is disturbed as he finds himself getting up very slowly to avoid the problem. This has created some awkward situations at his workplace and in social settings. His blood pressure while seated is 120/80 mm Hg, and upon standing it falls to 100/68 mm Hg. The physical examination is unremarkable except for a strong odor suggestive of marijuana use. The patient denies drug use and insists the odor is due to his roommate who smokes marijuana for medical purposes. No pallor or signs of dehydration are seen. The lab results are as follows:
Serum Glucose 90 mg/dL
Sodium 140 mEq/L
Potassium 4.1 mEq/L
Chloride 100 mEq/L
Serum Creatinine 0.8 mg/dL
Blood Urea Nitrogen 9 mg/dL
Hemoglobin (Hb) Concentration 15.3 g/dL
Mean Corpuscular Volume (MCV) 83 fl
Reticulocyte count 0.5%
Erythrocyte count 5.3 million/mm3
Platelet count 200,000/mm3
The ECG shows no abnormal finding. Which of the following could alleviate this patient’s symptoms?
A. Sodium chloride infusion
B. Inhibition of the baroreceptor response
C. Increased parasympathetic stimulation
D. Carotid massage
E. Alpha 1 receptor activation (Correct Answer)
Explanation: ***Alpha 1 receptor activation***
- Patients with **orthostatic hypotension** benefit from medications that increase **peripheral vasoconstriction**.
- **Alpha-1 adrenergic agonists** (such as midodrine) stimulate vasoconstriction, leading to an increase in **mean arterial pressure** and ameliorating orthostatic symptoms.
- This is the **most effective pharmacologic intervention** for this patient who has failed conservative measures.
*Sodium chloride infusion*
- While **increased sodium and fluid intake** can help orthostatic hypotension, this patient has already been **drinking lots of fluids** without improvement.
- His normal **hemoglobin**, **electrolytes**, and absence of dehydration signs suggest euvolemia.
- Although IV saline or increased salt intake may provide some benefit, it is less effective than targeted pharmacologic vasoconstriction, especially when conservative hydration measures have already failed.
*Inhibition of the baroreceptor response*
- The baroreceptors are crucial in maintaining blood pressure homeostasis by sensing changes in blood pressure and initiating reflex adjustments.
- **Inhibiting the baroreceptor response** would remove an important compensatory mechanism, potentially worsening orthostatic hypotension rather than improving it.
*Increased parasympathetic stimulation*
- Increased **parasympathetic activity** generally leads to **vasodilation** and a decrease in heart rate, which would exacerbate rather than alleviate orthostatic hypotension.
- The symptoms of orthostatic hypotension are primarily due to inadequate sympathetic response upon standing.
*Carotid massage*
- **Carotid massage** is a maneuver that stimulates the **baroreceptors** in the carotid sinus, leading to increased parasympathetic tone and decreased sympathetic output.
- This typically results in a **reduction in heart rate and blood pressure**, which would worsen the patient's existing orthostatic hypotension.
Question 646: A 7-year-old boy with asthma is brought to the physician because of a 1-month history of worsening shortness of breath and cough. The mother reports that the shortness of breath usually occurs when he is exercising with his older brother. His only medication is an albuterol inhaler that is taken as needed. The physician considers adding zafirlukast to his drug regimen. Which of the following is the most likely mechanism of action of this drug?
A. Antagonism at muscarinic receptors
B. Blockade of 5-lipoxygenase pathway
C. Inhibition of mast cell degranulation
D. Inhibition of phosphodiesterase
E. Antagonism at leukotriene receptors (Correct Answer)
Explanation: ***Antagonism at leukotriene receptors***
- **Zafirlukast** is a **leukotriene receptor antagonist** (LTRA) that blocks the action of leukotrienes at their CysLT1 receptors.
- This action helps to reduce **bronchoconstriction**, airway edema, and inflammation, which are key features of asthma pathophysiology.
*Antagonism at muscarinic receptors*
- This is the mechanism of action for **anticholinergic bronchodilators** like **ipratropium** or **tiotropium**, which are not **zafirlukast**.
- These drugs primarily prevent **acetylcholine-induced bronchoconstriction** but do not target the leukotriene pathway.
*Blockade of 5-lipoxygenase pathway*
- This is the mechanism of **zileuton**, a **leukotriene synthesis inhibitor**, which prevents the formation of all leukotrienes.
- While it targets leukotrienes, it is distinct from **receptor antagonism**, which is how **zafirlukast** works.
*Inhibition of mast cell degranulation*
- This is the mechanism of **mast cell stabilizers** such as **cromolyn sodium** or **nedocromil**, which prevent the release of inflammatory mediators.
- This action differs from the direct receptor blockade provided by **zafirlukast**.
*Inhibition of phosphodiesterase*
- This is the mechanism of **methylxanthines** like **theophylline**, which increase intracellular cAMP and lead to **bronchodilation**.
- This is a distinct pharmacological class and mechanism from **zafirlukast**.
Question 647: A 38-year-old man comes to the physician because of a 2-year-history of cough and progressively worsening breathlessness. He has smoked 1 pack of cigarettes daily for the past 10 years. Physical examination shows contraction of the anterior scalene and sternocleidomastoid muscles during inspiration. An x-ray of the chest shows flattening of the diaphragm and increased radiolucency in the lower lung fields. Further analysis shows increased activity of an isoform of elastase that is normally inhibited by alpha-1-antitrypsin. The cells that produce this isoform of elastase were most likely stimulated to enter the site of inflammation by which of the following substances?
A. Leukotriene B4 (Correct Answer)
B. Thromboxane A2
C. Lactoferrin
D. Interferon gamma
E. High-molecular-weight kininogen
Explanation: ***Leukotriene B4***
- The patient's symptoms and findings (cough, breathlessness, smoking history, increased elastase activity, flattened diaphragm, increased radiolucency) are consistent with **emphysema**, specifically **centrilobular emphysema** secondary to smoking. The increased elastase activity, normally inhibited by alpha-1-antitrypsin, points to **neutrophilic elastase**.
- **Leukotriene B4 (LTB4)** is a potent **chemoattractant for neutrophils**, drawing them to the site of inflammation in the lungs where they release elastase, contributing to alveolar destruction.
*Thromboxane A2*
- **Thromboxane A2** is primarily involved in **platelet aggregation** and **vasoconstriction**.
- It does not serve as a direct chemoattractant for neutrophils in the context of emphysema.
*Lactoferrin*
- **Lactoferrin** is an **iron-binding protein** found in various secretions and within neutrophil granules, acting as an antimicrobial agent and modulating immune responses.
- While present in neutrophils, it is not a primary chemoattractant for these cells to the site of inflammation.
*Interferon gamma*
- **Interferon gamma (IFN-$\gamma$)** is a cytokine produced by T cells and NK cells, important for **antiviral and antitumor immunity** and macrophage activation.
- It plays a role in chronic inflammation but is not a direct chemoattractant for neutrophils in the same manner as LTB4.
*High-molecular-weight kininogen*
- **High-molecular-weight kininogen (HMWK)** is a protein involved in the **coagulation cascade** and the **kallikrein-kinin system**, leading to the production of bradykinin.
- Its primary role is not as a direct chemoattractant for neutrophils in the inflammatory process leading to emphysema.
Question 648: A 10-year-old boy presents to the emergency department with sudden shortness of breath. He was playing in the school garden and suddenly started to complain of abdominal pain. He then vomited a few times. An hour later in the hospital, he slowly developed a rash on his chest, arms, and legs. His breathing became faster with audible wheezing. On physical examination, his vital signs are as follows: the temperature is 37.0°C (98.6°F), the blood pressure is 100/60 mm Hg, the pulse is 130/min, and the respiratory rate is 25/min. A rash is on his right arm, as shown in the image. After being administered appropriate treatment, the boy improves significantly, and he is able to breathe comfortably. Which of the following is the best marker that could be measured in the serum of this boy to help establish a definitive diagnosis?
A. Histamine
B. Serotonin
C. Leukotrienes
D. Prostaglandin D2
E. Tryptase (Correct Answer)
Explanation: ***Tryptase***
- **Tryptase** is an enzyme released almost exclusively from **mast cells** during an allergic reaction, making it an excellent marker for **anaphylaxis**.
- Its levels peak 1-2 hours after the start of symptoms and can remain elevated for several hours, providing a diagnostic window for confirmation.
*Histamine*
- While **histamine** is indeed a primary mediator in allergic reactions and anaphylaxis, it has a very short half-life in the bloodstream.
- Serum **histamine** levels rapidly return to normal, making it difficult to measure significantly elevated levels in a clinical setting, especially an hour after symptom onset.
*Serotonin*
- **Serotonin** is primarily involved in various physiological processes, including mood, sleep, and digestion, and is released by **platelets** and enterochromaffin cells.
- While it can play a role in some inflammatory responses, it is not a direct or definitive marker specifically for **mast cell degranulation** or anaphylaxis.
*Leukotrienes*
- **Leukotrienes** are potent inflammatory mediators released during allergic reactions, contributing to bronchoconstriction and increased vascular permeability.
- However, their measurement in serum is typically more complex and less specific for diagnosing acute **anaphylaxis** compared to tryptase.
*Prostaglandin D2*
- **Prostaglandin D2** is released from mast cells and contributes to the symptoms of anaphylaxis, including bronchoconstriction and vasodilation.
- Similar to leukotrienes, laboratory measurement is less common and often less readily available or specific for confirming generalized **mast cell activation** in an acute setting than tryptase.
Question 649: A 17-year-old high school student is brought to the emergency department because of irritability and rapid breathing. He appears agitated and is diaphoretic. His temperature is 38.3°C (101°F), pulse is 129/min, respirations are 28/min, and blood pressure is 158/95 mmHg. His pupils are dilated. An ECG shows sinus tachycardia. Which of the following substances is used to make the drug this patient has most likely taken?
A. Ergotamine
B. Codeine
C. Sodium oxybate
D. Homatropine
E. Pseudoephedrine (Correct Answer)
Explanation: ***Pseudoephedrine***
- This patient's symptoms (irritability, agitation, rapid breathing, tachycardia, hypertension, dilated pupils, and diaphoresis) are consistent with **sympathomimetic toxicity**, often seen with stimulants like **methamphetamine**.
- **Pseudoephedrine** is a common over-the-counter decongestant that can be chemically converted into methamphetamine through a process called **reduction**.
*Ergotamine*
- **Ergotamine** is an ergot alkaloid used to treat migraines; it causes vasoconstriction and can lead to symptoms like nausea, vomiting, and peripheral ischemia, which do not fully align with the patient's presentation.
- While it can cause elevated blood pressure, the widespread stimulant effects and agitation are less typical, and it's not a common precursor for illicit stimulant synthesis.
*Codeine*
- **Codeine** is an opioid; overdose would present with central nervous system depression, respiratory depression, and miosis (pinpoint pupils), which is the opposite of this patient's dilated pupils and agitated state.
- It is a precursor to certain other opioids (e.g., desomorphine or "krokodil"), but not to the type of stimulant producing these symptoms.
*Sodium oxybate*
- **Sodium oxybate** (GHB) is a central nervous system depressant and would cause sedation, bradycardia, and respiratory depression, not the stimulant toxidrome observed.
- It is not commonly used as a precursor for illicit stimulants causing sympathomimetic effects.
*Homatropine*
- **Homatropine** is an anticholinergic agent, which can cause dilated pupils, tachycardia, and a dry mouth, but typically not severe diaphoresis with agitation to this degree; also less common for illicit drug manufacturing.
- While it fits some anticholinergic toxidrome features, it is not a direct precursor for street drugs causing such profound sympathomimetic effects.
Question 650: A 60-year-old man is brought to the emergency department because of a 30-minute history of dizziness and shortness of breath. After establishing the diagnosis, treatment with a drug is administered. Shortly after administration, the patient develops severe left eye pain and decreased vision of the left eye, along with nausea and vomiting. Ophthalmologic examination shows a fixed, mid-dilated pupil and a narrowed anterior chamber of the left eye. The patient was most likely treated for which of the following conditions?
A. Hypertensive crisis
B. Atrioventricular block (Correct Answer)
C. Viral pleuritis
D. Pulmonary embolism
E. Mitral regurgitation
Explanation: **Atrioventricular block**
- The medication likely administered was **atropine**, a muscarinic antagonist used to treat symptomatic bradycardia from AV block.
- Atropine can precipitate **acute angle-closure glaucoma** due to its mydriatic effect, causing eye pain, decreased vision, and a fixed, mid-dilated pupil.
*Hypertensive crisis*
- Treatment for hypertensive crisis typically involves antihypertensive medications like **labetalol or nitroglycerin**, which do not cause acute angle-closure glaucoma.
- Symptoms of hypertensive crisis primarily relate to end-organ damage from high blood pressure, not acute ocular symptoms.
*Viral pleuritis*
- Viral pleuritis is an inflammatory condition of the pleura causing **pleuritic chest pain**, not cardiac symptoms, and is typically treated with NSAIDs.
- The treatment for viral pleuritis would not involve atropine or lead to acute angle-closure glaucoma.
*Pulmonary embolism*
- Pulmonary embolism presents with **acute dyspnea and hypoxemia** and is treated with anticoagulants.
- Such treatment would not cause the described ocular side effects or be mistaken for a condition requiring atropine.
*Mitral regurgitation*
- Mitral regurgitation is a valvular heart disease with symptoms often including **dyspnea on exertion** and fatigue, not acute dizziness and shortness of breath requiring immediate atropine.
- Treatment for acute mitral regurgitation typically involves vasodilators or surgical intervention, not atropine, and does not cause acute angle-closure glaucoma.