A 72-year-old man presents to the primary care clinic for evaluation of progressive fatigue and weight loss. His past medical history is significant for hypercholesterolemia, type 2 diabetes mellitus, aortic stenosis, and chronic renal insufficiency. He endorses being well-rested after waking from sleep but fatiguing rapidly during the day. In addition, he states that he has lost 15lbs over the previous month. His temperature is 98.3°F (36.8°C), pulse is 100/min, blood pressure is 110/85 mmHg, respirations are 16/min, and oxygen saturation is 96% on room air. Physical exam is notable for conjunctival pallor and scattered areas of ecchymoses. His laboratory results are shown below:
Serum:
Na+: 140 mEq/L
K+: 4.0 mEq/L
Cl-: 101 mEq/L
HCO3-: 22 mEq/L
BUN: 30 mg/dL
Glucose: 160 mg/dL
Creatinine: 1.9 mg/dL
Leukocyte count: 1,100/mm^3
Absolute neutrophil count 920/mm^3
Hemoglobin 8.4 g/dL
Platelet count: 45,000/mm^3
Mean corpuscular hemoglobin concentration: 34%
Red blood cell distribution width: 12.0%
Mean corpuscular volume: 92 µm^3
Lactate dehydrogenase: 456 IU/L
Haptoglobin 120 mg/dL
Fibrinogen 214 mg/dL
A bone marrow biopsy is performed which shows cells that are CD19+, CD20+, CD11c+, and stain with acid phosphatase 5 and tartrate-resistant. Which of the following is the next best step in the treatment of his disorder?
Q262
A 38-year-old woman presents with fever and acute onset chest pain for the past 12 hours. She describes the pain as severe, sharp and stabbing in character, and localized to the retrosternal area. She also says the pain is worse when she breathes deeply or coughs. Past medical history is significant for recently diagnosed systemic lupus erythematosus (SLE). Her vital signs include: blood pressure 110/75 mm Hg, pulse 95/min, and temperature 38.0°C (100.4°F). Physical examination is significant for a friction rub heard best at the lower left sternal border. Which of the following is the most likely diagnosis in this patient?
Q263
A 20-year-old man presents to the doctor's office for advice on improving his health. He admits to eating mostly junk food, and he knows that he should lose some weight. His daily physical activity is limited to walking around the college campus between classes. Except for an occasional headache for which he takes acetaminophen, he has no health concerns and takes no other medications. He denies smoking and illicit drug use, but admits to occasional beer binge drinking on weekends. He is sexually active with his current girlfriend and regularly uses condoms. His mother has type 2 diabetes mellitus and obesity, while his father has hypertension and hypercholesterolemia. The pulse is 74/min, the respiratory rate is 16/min, and the blood pressure is 130/76 mm Hg. The body mass index (BMI) is 29 kg/m2. Physical examination reveals an overweight young male, and the rest is otherwise unremarkable. The routine lab test results are as follows:
Serum Glucose (fasting) 100 mg/dL
Serum Electrolytes:
Sodium 141 mEq/L
Potassium 4.0 mEq/L
Chloride 100 mEq/L
Cholesterol, total 190 mg/dL
HDL-cholesterol 42 mg/dL
LDL-cholesterol 70 mg/dL
Triglycerides 184 mg/dL
Urinalysis:
Glucose Negative
Ketones Negative
Leukocytes Negative
Nitrites Negative
RBCs Negative
Casts Negative
Which of the following lifestyle changes would most likely benefit this patient the most?
Q264
A 53-year-old man comes to the emergency department because of a 1-month history of cough productive of small amounts of blood-tinged sputum. During this time, he has also developed fatigue, myalgia, and shortness of breath on exertion. He has had a 4-lb (2-kg) weight loss over the past 2 months. He has no personal history of serious illness. His mother has systemic lupus erythematosus. His temperature is 37.2°C (99.0 °F), pulse is 98/min, respirations are 22/min, and blood pressure is 152/98 mm Hg. Diffuse rhonchi are heard on auscultation of the chest bilaterally. There are multiple palpable, erythematous, nonblanching lesions on the lower extremities bilaterally. Laboratory studies show:
Leukocyte count 12,300 cells/mm3
Platelet count 400,000 cells/mm3
Erythrocyte sedimentation rate 83 mm/hr
Serum
Creatinine 2.1 mg/dL
Antinuclear antibody 1:40
Urine
Protein 3+
Blood 2+
RBC casts numerous
A biopsy specimen of the skin shows inflammation of the arterioles and capillaries without granuloma formation. Further evaluation of this patient is most likely to show which of the following findings?
Q265
A 30-year-old woman presents to the emergency department in a state of confusion and disorientation that started this morning. She is accompanied by her husband who says that she has been unwell for about one week. She has been complaining of fatigue. Her husband says that this morning, she also complained that her urine was dark red in color and that there were some red spots over her legs. He did notice some changes in her level of consciousness that worsened over time and he decided to bring her in today. She does not have a significant medical history. Physical examination shows petechiae over her arms and legs. She is conscious but drowsy and disoriented and unable to answer the physician’s questions appropriately. Her temperature is 38.3°C (100.9°F), blood pressure is 160/100 mm Hg, pulse rate is 90/min, and respiratory rate is 20/min.
Laboratory studies show:
Hemoglobin 10 g/dL
Leukocyte count 9,000/mm3
Platelet count 30,000/mm3
Bleeding time 10 min
Prothrombin time 12 s
Activated partial thromboplastin time 30 s
D-dimer 0.4 mg/L (normal < 0.5 mg/L)
Serum fibrinogen 350 mg/dL (normal 200–400 mg/dL)
Serum bilirubin (indirect) 2.2 mg/dL
Serum creatinine 1.5 mg/dL
Serum LDH 1,010 U/L
Based on her history, and her physical and laboratory findings, which of the following is the most likely pathophysiology for her presentation?
Q266
A 31-year-old woman presents to the clinic with shortness of breath, palpitations, and fatigue. She has had these symptoms over the last several weeks. She had been tolerating these symptoms until last night when she could not fall asleep due to palpitations. She has a past medical history of infective endocarditis 6 months ago that was successfully treated with antibiotics. She does not smoke or drink alcohol. Her blood pressure is 138/89 mm Hg and her pulse is 76/min and regular. The cardiac exam reveals a soft S1, S3 gallop, a hyperdynamic apex beat, and a pansystolic murmur that radiates to the axilla on auscultation. Echocardiography reveals incompetence of one of the valves. Which of the following sites is the best position to auscultate this defect?
Q267
A 43-year-old man presents to a primary care clinic complaining of several months of fatigue and difficulty concentrating at work. He is tired throughout the day and often falls asleep briefly at work. He sleeps for 9 hours per night, falling asleep easily, waking up several times in the middle of the night, and then having trouble waking up in the morning. Physical exam is notable for obesity and a large neck circumference. His temperature is 98°F (36.7°C), blood pressure is 150/90 mmHg, pulse is 75/min, respirations are 22/min, and BMI is 33 kg/m^2. The rest of the physical exam is normal. Which of the following is the most likely cause of his fatigue?
Q268
A 23-year-old man presents to his physician's office with increasing breathlessness over the past one month. He was diagnosed with asthma when he was a child and has been able to keep his symptoms under control with a Ventolin inhaler. However, over the past year or so he has found that he gets out of breath on several occasions during the week. He wakes up at least once a week with breathlessness. He finds that he feels out of breath during his weekly football matches, which never used to happen before. He has to sit down and take a couple of puffs of his inhaler to feel better. He has no other pertinent history at this moment, except that he started on a new job painting houses about 5 months ago. His physical examination does not show anything significant. His peak expiratory flow rate during spirometry averages about 85% of the normal value, after conducting the test 3 times. Which of the following would be the next best step in management?
Q269
A 40-year-old man presents to a clinic in Michigan in December complaining of painful blue fingers and toes. He also complains of numbness and tingling. The patient’s vital signs are within normal limits, and his symptoms typically disappear when he comes back into a warm room. The patient also notes that he recently moved to the area from Arizona and had recently recovered from a viral infection in which he had a low-grade fever and severe lymphadenopathy. Which of the following tests would most likely be positive in this patient?
Q270
A 52-year-old woman is accompanied by her husband to the emergency department with a severe occipital headache that started suddenly an hour ago. She is drowsy but able to answer the physician's questions. She describes it as the worst headache she has ever had, 9/10 in intensity. The husband says it was initially localized to the occiput but has now spread all over her head and she also complained of a generalized heaviness. She took an ibuprofen without experiencing any relief. She also complains of blurry vision and nausea and had 1 episode of vomiting. She denies a recent history of fever, chills, numbness, or seizures. Her past medical history is significant for hypertension controlled with lisinopril and metoprolol. On examination, she is drowsy but oriented. Papilledema is seen on ophthalmoscopy. Neck flexion is difficult and painful. The rest of the exam is unremarkable. Her blood pressure is 160/100 mm Hg, heart rate is 100/min, and temperature is 37.0°C (98.6°F). The ECG, cardiac enzymes, and laboratory studies are normal. Lumbar puncture results are as follows:
Opening pressure 210 mm H2O
RBC 50/mm3, numbers steady over 4 test tubes
Cell count 5/mm3
Glucose 60 mg/dL
Proteins 100 mg/dL
The patient is admitted to the ICU for further management. Which of the following is the most likely pathophysiology based on her history and CSF findings?
Cardiology US Medical PG Practice Questions and MCQs
Question 261: A 72-year-old man presents to the primary care clinic for evaluation of progressive fatigue and weight loss. His past medical history is significant for hypercholesterolemia, type 2 diabetes mellitus, aortic stenosis, and chronic renal insufficiency. He endorses being well-rested after waking from sleep but fatiguing rapidly during the day. In addition, he states that he has lost 15lbs over the previous month. His temperature is 98.3°F (36.8°C), pulse is 100/min, blood pressure is 110/85 mmHg, respirations are 16/min, and oxygen saturation is 96% on room air. Physical exam is notable for conjunctival pallor and scattered areas of ecchymoses. His laboratory results are shown below:
Serum:
Na+: 140 mEq/L
K+: 4.0 mEq/L
Cl-: 101 mEq/L
HCO3-: 22 mEq/L
BUN: 30 mg/dL
Glucose: 160 mg/dL
Creatinine: 1.9 mg/dL
Leukocyte count: 1,100/mm^3
Absolute neutrophil count 920/mm^3
Hemoglobin 8.4 g/dL
Platelet count: 45,000/mm^3
Mean corpuscular hemoglobin concentration: 34%
Red blood cell distribution width: 12.0%
Mean corpuscular volume: 92 µm^3
Lactate dehydrogenase: 456 IU/L
Haptoglobin 120 mg/dL
Fibrinogen 214 mg/dL
A bone marrow biopsy is performed which shows cells that are CD19+, CD20+, CD11c+, and stain with acid phosphatase 5 and tartrate-resistant. Which of the following is the next best step in the treatment of his disorder?
A. Cyclophosphamide
B. Hydroxyurea
C. Cladribine (Correct Answer)
D. Filgrastim
E. Doxorubicin
Explanation: ***Cladribine***
- The patient's blood work (pancytopenia: **leukopenia**, **anemia**, **thrombocytopenia**) along with bone marrow biopsy findings (**CD19+, CD20+, CD11c+, tartrate-resistant acid phosphatase-positive** cells) are highly indicative of **hairy cell leukemia**.
- **Cladribine** is a purine analog, which is considered the most effective first-line treatment for hairy cell leukemia, often leading to long-lasting remissions.
*Cyclophosphamide*
- This is an **alkylating agent** used in various cancers and autoimmune conditions, but it is not the most effective or preferred first-line treatment for hairy cell leukemia.
- Cyclophosphamide is associated with significant side effects and would likely be reserved for other hematological malignancies.
*Hydroxyurea*
- **Hydroxyurea** is a ribonucleotide reductase inhibitor primarily used in myeloproliferative disorders like **chronic myeloid leukemia** or **polycythemia vera** to reduce cell counts.
- While it can lower white blood cell counts, it is not curative and not the standard primary therapy for hairy cell leukemia.
*Filgrastim*
- **Filgrastim** is a **granulocyte colony-stimulating factor (G-CSF)** used to stimulate neutrophil production, often to counter neutropenia caused by chemotherapy.
- It would not be used to treat hairy cell leukemia itself, and in some cases, can even paradoxically induce leukocytosis, which may not be desired in a condition characterized by abnormal white blood cells.
*Doxorubicin*
- **Doxorubicin** is an **anthracycline antibiotic** used in the treatment of many cancers (e.g., lymphomas, breast cancer, sarcomas) but not hairy cell leukemia.
- Its mechanism of action involves DNA intercalation and inhibition of topoisomerase II, which is not the primary target for hairy cell leukemia therapy.
Question 262: A 38-year-old woman presents with fever and acute onset chest pain for the past 12 hours. She describes the pain as severe, sharp and stabbing in character, and localized to the retrosternal area. She also says the pain is worse when she breathes deeply or coughs. Past medical history is significant for recently diagnosed systemic lupus erythematosus (SLE). Her vital signs include: blood pressure 110/75 mm Hg, pulse 95/min, and temperature 38.0°C (100.4°F). Physical examination is significant for a friction rub heard best at the lower left sternal border. Which of the following is the most likely diagnosis in this patient?
A. Acute myocardial infarction
B. Septic shock
C. Pericardial tamponade
D. Constrictive pericarditis
E. Acute pericarditis (Correct Answer)
Explanation: ***Acute pericarditis***
- This patient's symptoms of **acute onset, sharp, retrosternal chest pain** that is **worse with deep breathing or coughing**, accompanied by a **pericardial friction rub** and fever, are classic for **acute pericarditis**.
- The history of **systemic lupus erythematosus (SLE)** is a significant risk factor for pericarditis, as SLE can cause serositis (inflammation of serous membranes including the pericardium).
*Acute myocardial infarction*
- While chest pain is present, the description of **sharp, stabbing pain worse with breathing** is more typical of pericarditis than the **crushing, pressure-like pain of an MI** that often radiates to the arm or jaw.
- The presence of a **pericardial friction rub** is highly suggestive of pericarditis and not typically found in MI.
*Septic shock*
- This patient's vital signs, including a blood pressure of **110/75 mmHg**, do not indicate **hypotension** as seen in septic shock.
- While fever is present, the primary presentation is **chest pain** and a **friction rub**, not generalized signs of severe infection and organ dysfunction.
*Pericardial tamponade*
- Pericardial tamponade would present with signs of **hemodynamic compromise** such as **hypotension**, **tachycardia**, **muffled heart sounds**, and **jugular venous distention (Beck's triad)**, which are not described.
- The primary symptom is **chest pain** and a **friction rub** indicative of inflammation, not significant fluid accumulation causing cardiac compression.
*Constrictive pericarditis*
- **Constrictive pericarditis** typically presents with signs of **chronic right-sided heart failure** such as **peripheral edema**, **ascites**, and **jugular venous distention**, often after a prolonged course of pericardial inflammation.
- This patient presents with **acute symptoms** and signs of **active inflammation** (fever, friction rub), which is not consistent with the chronic nature of constrictive pericarditis.
Question 263: A 20-year-old man presents to the doctor's office for advice on improving his health. He admits to eating mostly junk food, and he knows that he should lose some weight. His daily physical activity is limited to walking around the college campus between classes. Except for an occasional headache for which he takes acetaminophen, he has no health concerns and takes no other medications. He denies smoking and illicit drug use, but admits to occasional beer binge drinking on weekends. He is sexually active with his current girlfriend and regularly uses condoms. His mother has type 2 diabetes mellitus and obesity, while his father has hypertension and hypercholesterolemia. The pulse is 74/min, the respiratory rate is 16/min, and the blood pressure is 130/76 mm Hg. The body mass index (BMI) is 29 kg/m2. Physical examination reveals an overweight young male, and the rest is otherwise unremarkable. The routine lab test results are as follows:
Serum Glucose (fasting) 100 mg/dL
Serum Electrolytes:
Sodium 141 mEq/L
Potassium 4.0 mEq/L
Chloride 100 mEq/L
Cholesterol, total 190 mg/dL
HDL-cholesterol 42 mg/dL
LDL-cholesterol 70 mg/dL
Triglycerides 184 mg/dL
Urinalysis:
Glucose Negative
Ketones Negative
Leukocytes Negative
Nitrites Negative
RBCs Negative
Casts Negative
Which of the following lifestyle changes would most likely benefit this patient the most?
A. A low sodium diet
B. Starting a multivitamin
C. Increasing daily water intake
D. Weight reduction (Correct Answer)
E. Increasing dietary fiber
Explanation: ***Weight reduction***
- The patient has a **BMI of 29 kg/m2**, which classifies him as **overweight**, and his diet consists mostly of junk food, making weight reduction a primary and impactful lifestyle change.
- Weight loss significantly improves multiple health markers, including **blood pressure**, **lipid profile**, and **insulin sensitivity**, reducing his risk for conditions like **type 2 diabetes** and **hypertension** that run in his family.
- The patient shows early signs of **metabolic syndrome** (elevated BP, low HDL 42 mg/dL, triglycerides 184 mg/dL, impaired fasting glucose 100 mg/dL), which weight reduction directly addresses.
*A low sodium diet*
- While his father has hypertension, this patient's blood pressure is **130/76 mm Hg**, which is in the **elevated range** (120-129/<80 mm Hg), not yet meeting criteria for hypertension (≥130/80 mm Hg).
- While a low sodium diet is generally healthy and can help prevent hypertension, addressing his **overweight status** and **poor dietary habits** would yield more comprehensive benefits first.
*Starting a multivitamin*
- The patient has no symptoms or signs of **nutrient deficiencies**, and his routine lab tests are normal.
- There is generally **no strong evidence** to support routine multivitamin supplementation in otherwise healthy individuals with no specific deficiencies.
*Increasing daily water intake*
- There is no indication that the patient is **dehydrated** or has any conditions that would specifically benefit from a significant increase in water intake.
- While adequate hydration is important, it is **not the most impactful intervention** for his current health profile compared to addressing his diet and weight.
*Increasing dietary fiber*
- Increasing dietary fiber is beneficial for **digestive health** and can help with **satiety** and **cholesterol management**.
- However, his primary issue is his overall "junk food" diet and overweight status; tackling these directly through **comprehensive dietary changes** (which would include more fiber) and **weight reduction** would be more beneficial than focusing solely on fiber intake initially.
Question 264: A 53-year-old man comes to the emergency department because of a 1-month history of cough productive of small amounts of blood-tinged sputum. During this time, he has also developed fatigue, myalgia, and shortness of breath on exertion. He has had a 4-lb (2-kg) weight loss over the past 2 months. He has no personal history of serious illness. His mother has systemic lupus erythematosus. His temperature is 37.2°C (99.0 °F), pulse is 98/min, respirations are 22/min, and blood pressure is 152/98 mm Hg. Diffuse rhonchi are heard on auscultation of the chest bilaterally. There are multiple palpable, erythematous, nonblanching lesions on the lower extremities bilaterally. Laboratory studies show:
Leukocyte count 12,300 cells/mm3
Platelet count 400,000 cells/mm3
Erythrocyte sedimentation rate 83 mm/hr
Serum
Creatinine 2.1 mg/dL
Antinuclear antibody 1:40
Urine
Protein 3+
Blood 2+
RBC casts numerous
A biopsy specimen of the skin shows inflammation of the arterioles and capillaries without granuloma formation. Further evaluation of this patient is most likely to show which of the following findings?
A. Hepatitis B surface antigen
B. Increased serum cryoglobulins
C. Myeloperoxidase antineutrophil cytoplasmic antibody (Correct Answer)
D. Anti-glomerular basement membrane antibodies
E. Anti-double stranded DNA antibodies
Explanation: ***Myeloperoxidase antineutrophil cytoplasmic antibody***
- The patient presents with **pulmonary-renal syndrome** and vasculitic skin lesions.
- The skin biopsy shows **inflammation of arterioles and capillaries without granuloma formation**, pointing towards a small vessel vasculitis such as **microscopic polyangiitis**, which is commonly associated with **MPO-ANCA (p-ANCA)** positivity.
*Hepatitis B surface antigen*
- **Polyarteritis nodosa** is a medium-sized vessel vasculitis often associated with **hepatitis B virus infection**.
- However, the skin biopsy showing **small vessel vasculitis** (arterioles and capillaries) makes polyarteritis nodosa less likely.
*Increased serum cryoglobulins*
- **Cryoglobulinemic vasculitis** is associated with **hepatitis C virus infection** and often presents with palpable purpura, arthralgias, and renal involvement.
- While the patient has palpable purpura and renal involvement, the absence of **hepatitis C risk factors** and the specific biopsy findings make this less probable than microscopic polyangiitis.
*Anti-glomerular basement membrane antibodies*
- **Goodpasture syndrome** is characterized by rapidly progressive glomerulonephritis and pulmonary hemorrhage due to **anti-GBM antibodies**.
- While the patient has both pulmonary and renal involvement, a skin vasculitis is not typical for Goodpasture syndrome, and the biopsy would show **linear IgG deposition** along the GBM, not inflammation of arterioles and capillaries.
*Anti-double stranded DNA antibodies*
- **Anti-dsDNA antibodies** are highly specific for **systemic lupus erythematosus (SLE)**, which can cause vasculitis and renal disease.
- While the patient's mother has SLE, his clinical presentation, particularly the lung involvement and the specific type of skin vasculitis, is more classic for an **ANCA-associated vasculitis** than for SLE.
Question 265: A 30-year-old woman presents to the emergency department in a state of confusion and disorientation that started this morning. She is accompanied by her husband who says that she has been unwell for about one week. She has been complaining of fatigue. Her husband says that this morning, she also complained that her urine was dark red in color and that there were some red spots over her legs. He did notice some changes in her level of consciousness that worsened over time and he decided to bring her in today. She does not have a significant medical history. Physical examination shows petechiae over her arms and legs. She is conscious but drowsy and disoriented and unable to answer the physician’s questions appropriately. Her temperature is 38.3°C (100.9°F), blood pressure is 160/100 mm Hg, pulse rate is 90/min, and respiratory rate is 20/min.
Laboratory studies show:
Hemoglobin 10 g/dL
Leukocyte count 9,000/mm3
Platelet count 30,000/mm3
Bleeding time 10 min
Prothrombin time 12 s
Activated partial thromboplastin time 30 s
D-dimer 0.4 mg/L (normal < 0.5 mg/L)
Serum fibrinogen 350 mg/dL (normal 200–400 mg/dL)
Serum bilirubin (indirect) 2.2 mg/dL
Serum creatinine 1.5 mg/dL
Serum LDH 1,010 U/L
Based on her history, and her physical and laboratory findings, which of the following is the most likely pathophysiology for her presentation?
A. GPIIb/IIIa deficiency and failure of platelet aggregation
B. Systemic activation of blood coagulation
C. E. coli-mediated endothelial damage and formation of microthrombi
D. Antiplatelet antibodies
E. Decreased ADAMTS13 causing platelet adhesion and formation of microthrombi (Correct Answer)
Explanation: ***Decreased ADAMTS13 causing platelet adhesion and formation of microthrombi***
* The constellation of **fever, neurologic symptoms (confusion, disorientation), renal dysfunction (creatinine 1.5 mg/dL), microangiopathic hemolytic anemia (indirect bilirubin 2.2 mg/dL, high LDH, dark red urine), and thrombocytopenia (platelet count 30,000/mm3, petechiae)** is characteristic of **Thrombotic Thrombocytopenic Purpura (TTP)**.
* **TTP** is caused by a deficiency in the **ADAMTS13 enzyme**, which normally cleaves **large Von Willebrand Factor (vWF) multimers**. A deficiency leads to accumulation of these large vWF multimers, causing **uncontrolled platelet adhesion and aggregation**, forming **microthrombi** in small blood vessels. This results in **hemolytic anemia** (due to fragmentation of red blood cells passing through the partially occluded vessels), **thrombocytopenia** (due to platelet consumption), and **end-organ damage** (kidney, brain).
*GPIIb/IIIa deficiency and failure of platelet aggregation*
* **GPIIb/IIIa deficiency (Glanzmann thrombasthenia)** is a disorder of **platelet aggregation**, leading to severe bleeding.
* Patients typically present with **mucocutaneous bleeding** and **normal platelet counts**. This patient has severe thrombocytopenia and evidence of microangiopathic hemolysis.
*Systemic activation of blood coagulation*
* This describes **Disseminated Intravascular Coagulation (DIC)**. While DIC involves microthrombi and thrombocytopenia, it is also characterized by **prolonged PT and aPTT**, **decreased fibrinogen**, and **elevated D-dimer** due to widespread activation of the coagulation cascade and subsequent fibrinolysis.
* This patient's **PT, aPTT, D-dimer, and fibrinogen levels are normal**, ruling out DIC as the primary etiology.
*E. coli-mediated endothelial damage and formation of microthrombi*
* This description is suggestive of **Hemolytic Uremic Syndrome (HUS)**, often caused by **Shiga-toxin-producing E. coli (STEC)**. HUS shares features with TTP but typically presents with a prodrome of **bloody diarrhea** and more prominent **renal failure** without significant neurological involvement as seen in TTP.
* The patient in this scenario does not report preceding diarrheal illness, making TTP a more likely diagnosis given the prominent neurological symptoms and mild renal dysfunction.
*Antiplatelet antibodies*
* This mechanism is characteristic of **Immune Thrombocytopenic Purpura (ITP)**, where antibodies destroy platelets, leading to thrombocytopenia and bruising/bleeding.
* **ITP** usually presents with isolated **thrombocytopenia** and normal hemoglobin and renal function, without evidence of microangiopathic hemolytic anemia or neurologic symptoms.
Question 266: A 31-year-old woman presents to the clinic with shortness of breath, palpitations, and fatigue. She has had these symptoms over the last several weeks. She had been tolerating these symptoms until last night when she could not fall asleep due to palpitations. She has a past medical history of infective endocarditis 6 months ago that was successfully treated with antibiotics. She does not smoke or drink alcohol. Her blood pressure is 138/89 mm Hg and her pulse is 76/min and regular. The cardiac exam reveals a soft S1, S3 gallop, a hyperdynamic apex beat, and a pansystolic murmur that radiates to the axilla on auscultation. Echocardiography reveals incompetence of one of the valves. Which of the following sites is the best position to auscultate this defect?
A. Medial end of the 2nd intercostal space on the right side
B. 4th intercostal space at the midclavicular line on the left side
C. 5th intercostal space at the midclavicular line on the left side (Correct Answer)
D. Medial end of the 2nd intercostal space on the left side
E. Right lower end of the body of the sternum
Explanation: ***5th intercostal space at the midclavicular line on the left side***
- The patient's symptoms (shortness of breath, palpitations, fatigue, S3 gallop, hyperdynamic apex beat, and a pansystolic murmur radiating to the axilla) following infective endocarditis strongly suggest **mitral regurgitation**.
- The **mitral valve** is best auscultated at the **cardiac apex**, which is located at the **5th intercostal space at the midclavicular line on the left side**.
*Medial end of the 2nd intercostal space on the right side*
- This position is the **aortic area**, where murmurs related to the **aortic valve** (e.g., aortic stenosis or regurgitation) are best heard.
- An aortic murmur would not typically radiate to the axilla.
*4th intercostal space at the midclavicular line on the left side*
- This location is slightly above the typical apex beat and is not the primary auscultation site for any major cardiac valve.
- While close to the mitral area, it is not the optimal point for identifying mitral valve pathology.
*Medial end of the 2nd intercostal space on the left side*
- This position is the **pulmonic area**, where murmurs related to the **pulmonic valve** (e.g., pulmonary stenosis or regurgitation) are best heard.
- A pulmonic murmur would not cause a hyperdynamic apex beat or radiate to the axilla.
*Right lower end of the body of the sternum*
- This location corresponds to the **tricuspid area**, where murmurs related to the **tricuspid valve** (e.g., tricuspid regurgitation or stenosis) are best heard.
- Tricuspid murmurs are often amplified with inspiration and typically do not radiate to the axilla.
Question 267: A 43-year-old man presents to a primary care clinic complaining of several months of fatigue and difficulty concentrating at work. He is tired throughout the day and often falls asleep briefly at work. He sleeps for 9 hours per night, falling asleep easily, waking up several times in the middle of the night, and then having trouble waking up in the morning. Physical exam is notable for obesity and a large neck circumference. His temperature is 98°F (36.7°C), blood pressure is 150/90 mmHg, pulse is 75/min, respirations are 22/min, and BMI is 33 kg/m^2. The rest of the physical exam is normal. Which of the following is the most likely cause of his fatigue?
A. Obstructive sleep apnea (Correct Answer)
B. Chronic fatigue syndrome
C. Narcolepsy
D. Circadian rhythm sleep wake disorder
E. Hypothyroidism
Explanation: ***Obstructive sleep apnea***
- The patient's **obesity**, **large neck circumference**, chronic fatigue, daytime sleepiness, and **disrupted nocturnal sleep with multiple awakenings** are all classic symptoms and risk factors for **obstructive sleep apnea (OSA)**.
- The nocturnal awakenings occur due to **repeated upper airway obstruction** during sleep, causing brief arousals that fragment sleep architecture despite adequate time in bed.
- The high blood pressure and increased respirations are associated with the physiological stress of repeated airway obstruction and arousal during sleep.
- **OSA is strongly associated with obesity (BMI >30) and increased neck circumference**, both present in this patient.
*Chronic fatigue syndrome*
- While fatigue is a primary symptom, chronic fatigue syndrome typically involves **post-exertional malaise** and is not characterized by the specific pattern of sleep disruption and physical risk factors (obesity, large neck circumference) seen here.
- Diagnosis requires persistent, unexplained fatigue for at least six months, along with other defining symptoms like cognitive difficulties, but the detailed sleep pattern and physical findings point away from this.
*Narcolepsy*
- Narcolepsy is characterized by **uncontrollable daytime sleep attacks** and often involves **cataplexy** (sudden loss of muscle tone triggered by strong emotions).
- While daytime sleepiness is present, the patient's nocturnal sleep pattern (waking multiple times) and physical risk factors are not typical features of narcolepsy.
- Narcolepsy patients typically have **difficulty maintaining nighttime sleep** but do not have the obesity and large neck circumference risk factors.
*Circadian rhythm sleep wake disorder*
- These disorders involve a misalignment between the **internal sleep-wake clock** and the external environment or work schedule, leading to timing difficulties rather than chronic apnea-related sleep disruption.
- The patient's ability to fall asleep easily and the specific physical findings do not align with a primary circadian rhythm disorder.
*Hypothyroidism*
- Hypothyroidism can cause fatigue, weight gain, and sometimes daytime sleepiness, but it does not typically cause the specific pattern of **nocturnal awakenings** and has no direct link to a **large neck circumference** in the context of sleep quality.
- Other classic symptoms like cold intolerance, dry skin, bradycardia, and constipation are not mentioned, and a normal temperature makes severe hypothyroidism less likely.
Question 268: A 23-year-old man presents to his physician's office with increasing breathlessness over the past one month. He was diagnosed with asthma when he was a child and has been able to keep his symptoms under control with a Ventolin inhaler. However, over the past year or so he has found that he gets out of breath on several occasions during the week. He wakes up at least once a week with breathlessness. He finds that he feels out of breath during his weekly football matches, which never used to happen before. He has to sit down and take a couple of puffs of his inhaler to feel better. He has no other pertinent history at this moment, except that he started on a new job painting houses about 5 months ago. His physical examination does not show anything significant. His peak expiratory flow rate during spirometry averages about 85% of the normal value, after conducting the test 3 times. Which of the following would be the next best step in management?
A. Patch test
B. Follow up spirometry in 2 months
C. Arterial blood gas
D. Chest X-ray
E. Methacholine bronchoprovocation test (Correct Answer)
Explanation: ***Methacholine bronchoprovocation test***
- The patient's history, including **worsening asthma symptoms** despite previous control and a new exposure to paint, suggests a potential diagnosis of **occupational asthma**. A methacholine challenge test is indicated to confirm **airway hyperresponsiveness** if spirometry is inconclusive.
- Given the history of frequent symptoms, night awakenings, and impact on activity, this points to **uncontrolled asthma** or a new trigger. A positive test to methacholine would confirm **bronchial hyperreactivity**, which is essential for diagnosing asthma when baseline spirometry is near normal.
*Patch test*
- A patch test is used to identify **contact allergens** that cause **allergic contact dermatitis**, which presents as a rash rather than respiratory symptoms.
- It is not indicated for the diagnosis of **occupational asthma**, which involves inhalation of triggers.
*Follow up spirometry in 2 months*
- Waiting two months for follow-up spirometry would delay diagnosis and potential treatment for a patient with **worsening and uncontrolled asthma symptoms**.
- The current spirometry reading of **85% of normal** is not significantly obstructive enough to definitively diagnose asthma without further testing, especially given the history.
*Arterial blood gas*
- An ABG measures **blood gas levels** and acid-base balance, which is useful in assessing the severity of an acute asthma exacerbation or chronic respiratory failure.
- In a patient with partially controlled asthma and near-normal spirometry, an ABG is not typically the next best diagnostic step unless there are signs of severe respiratory distress or hypoxemia.
*Chest X-ray*
- A chest X-ray is primarily used to rule out other respiratory conditions like **pneumonia**, **pneumothorax**, or structural lung disease, which are not suggested by this patient's history.
- It's generally not indicated as a primary diagnostic tool for **asthma**, especially when symptoms are chronic and related to bronchoconstriction.
Question 269: A 40-year-old man presents to a clinic in Michigan in December complaining of painful blue fingers and toes. He also complains of numbness and tingling. The patient’s vital signs are within normal limits, and his symptoms typically disappear when he comes back into a warm room. The patient also notes that he recently moved to the area from Arizona and had recently recovered from a viral infection in which he had a low-grade fever and severe lymphadenopathy. Which of the following tests would most likely be positive in this patient?
A. Direct Coomb’s test with anti-C3 reagent (Correct Answer)
B. Anti-centromere antibody
C. Anti-Ro antibody
D. Indirect Coomb’s test
E. Direct Coomb’s test with anti-IgG reagent
Explanation: ***Direct Coombs test with anti-C3 reagent***
- The patient presents with classic symptoms of **cold agglutinin disease**, characterized by painful blue fingers and toes (acrocyanosis) triggered by cold exposure that resolves with warming.
- The recent **viral infection with severe lymphadenopathy** suggests infections such as **Mycoplasma pneumoniae, EBV, or CMV**, which are well-known triggers for cold agglutinin disease.
- Cold agglutinins are **IgM antibodies** that bind to red blood cells at cold temperatures, causing **complement activation** (C3d deposition) and **extravascular hemolysis**.
- The **direct Coombs test with anti-C3 reagent** detects complement (C3) bound to RBC surfaces and is the diagnostic test of choice for cold agglutinin disease.
- The recent move from Arizona to Michigan in December provides the cold exposure trigger needed to manifest symptoms.
*Direct Coombs test with anti-IgG reagent*
- This test detects **IgG antibodies bound to red blood cells** and is positive in **warm autoimmune hemolytic anemia**, not cold agglutinin disease.
- Cold agglutinin disease is mediated by **IgM antibodies and complement (C3)**, not IgG, so this test would be negative.
*Indirect Coombs test*
- The **indirect Coombs test** detects **free antibodies in serum** against RBCs and is used primarily for blood typing and cross-matching.
- While it may detect cold agglutinins in serum, the **direct Coombs with anti-C3** is the more specific and diagnostic test for cold agglutinin disease.
*Anti-centromere antibody*
- **Anti-centromere antibodies** are highly specific for **limited cutaneous systemic sclerosis (CREST syndrome)**, which can present with Raynaud's phenomenon.
- However, the **acute onset** following a viral illness, the **severe lymphadenopathy**, and the **cold-triggered acrocyanosis** are more consistent with cold agglutinin disease rather than a chronic autoimmune connective tissue disease.
- Systemic sclerosis typically has a more insidious onset and is not triggered by viral infections.
*Anti-Ro antibody*
- **Anti-Ro antibodies** are associated with **Sjögren's syndrome** and **systemic lupus erythematosus (SLE)**.
- While Raynaud's can occur in these conditions, the clinical presentation with recent viral infection, severe lymphadenopathy, and cold-triggered symptoms points to cold agglutinin disease rather than SLE or Sjögren's syndrome.
Question 270: A 52-year-old woman is accompanied by her husband to the emergency department with a severe occipital headache that started suddenly an hour ago. She is drowsy but able to answer the physician's questions. She describes it as the worst headache she has ever had, 9/10 in intensity. The husband says it was initially localized to the occiput but has now spread all over her head and she also complained of a generalized heaviness. She took an ibuprofen without experiencing any relief. She also complains of blurry vision and nausea and had 1 episode of vomiting. She denies a recent history of fever, chills, numbness, or seizures. Her past medical history is significant for hypertension controlled with lisinopril and metoprolol. On examination, she is drowsy but oriented. Papilledema is seen on ophthalmoscopy. Neck flexion is difficult and painful. The rest of the exam is unremarkable. Her blood pressure is 160/100 mm Hg, heart rate is 100/min, and temperature is 37.0°C (98.6°F). The ECG, cardiac enzymes, and laboratory studies are normal. Lumbar puncture results are as follows:
Opening pressure 210 mm H2O
RBC 50/mm3, numbers steady over 4 test tubes
Cell count 5/mm3
Glucose 60 mg/dL
Proteins 100 mg/dL
The patient is admitted to the ICU for further management. Which of the following is the most likely pathophysiology based on her history and CSF findings?
A. Rupture of the communicating branches of the cerebral arteries (Correct Answer)
B. Intracerebral bleed
C. Viral infection of the brain parenchyma
D. Bacterial infection of the meninges
E. Trauma during lumbar puncture
Explanation: ***Rupture of the communicating branches of the cerebral arteries***
- This presentation, with a **sudden-onset, severe occipital headache ("thunderclap headache")**, meningeal irritation (stiff neck), blurry vision, papilledema, and elevated intracranial pressure (high opening pressure, nausea, vomiting), is highly classic for a **subarachnoid hemorrhage (SAH)**.
- The **CSF findings** of grossly bloody fluid with consistent red blood cells (RBCs) across multiple tubes (indicating true hemorrhage, not traumatic tap), elevated protein, and normal glucose are diagnostic of SAH. The most common cause of spontaneous SAH is the rupture of a **saccular (berry) aneurysm**, frequently found in the communicating branches of cerebral arteries.
*Intracerebral bleed*
- While an intracerebral bleed can cause severe headache and neurological deficits, it typically presents with **focal neurological signs** corresponding to the brain region affected by the hematoma.
- Classic CSF findings in an intracerebral bleed, unless it ruptures into the ventricles or subarachnoid space, would generally be **acellular or mildly pleocytic**, not overtly bloody with high RBC counts.
*Viral infection of the brain parenchyma*
- **Viral encephalitis** would typically present with fever, altered mental status, and often focal neurological deficits or seizures.
- CSF findings for viral encephalitis would show **lymphocytic pleocytosis**, mildly elevated protein, and normal glucose, not significant RBCs.
*Bacterial infection of the meninges*
- **Bacterial meningitis** is characterized by fever, neck stiffness, and altered mental status. The headache is usually progressive, not thunderclap.
- CSF analysis would typically show **neutrophilic pleocytosis**, markedly elevated protein, **low glucose**, and often visible bacteria on gram stain, unlike this patient's findings.
*Trauma during lumbar puncture*
- A **traumatic lumbar puncture** can cause blood in the CSF, but the RBC count would typically **decrease progressively** in subsequent tubes as less contaminated fluid is collected.
- The presence of **xanthochromia** (not explicitly mentioned but usually present in SAH after several hours) and the clinical presentation of a thunderclap headache, papilledema, and meningeal signs prior to the LP make a traumatic tap unlikely as the primary pathology.