A 52-year-old man presents to a medical clinic to establish care. He has no known chronic illnesses but has not seen a physician in over 20 years. He generally feels well but occasionally has shortness of breath when he jogs and exercises. He smokes 2-5 cigarettes per day and uses IV heroin “now and then.” Physical exam is unremarkable. ECG shows prominent QRS voltage and left axis deviation. Trans-thoracic echocardiogram shows mild concentric left ventricular hypertrophy but is otherwise normal. Which of the following is the most likely etiology of the echocardiogram findings?
Q212
A 34-year-old woman comes to the physician because of a 3-month history of fatigue and a 4.5-kg (10-lb) weight loss despite eating more than usual. Her pulse is 115/min and blood pressure is 140/60 mm Hg. Physical examination shows warm, moist skin, and a diffuse, non-tender swelling over the anterior neck. Ophthalmologic examination shows swelling of the eyelids and proptosis bilaterally. Which of the following is the most likely cause of this patient's symptoms?
Q213
A 43-year-old man from Chile comes to the physician because of a 1-day history of upper back pain and difficulty swallowing. He has had pain in his shoulder and knee joints over the past 10 years. He is 190 cm (6 ft 3 in) tall and weighs 70.3 kg (155 lb); BMI is 19.4 kg/m2. His blood pressure is 142/86 mm Hg in the right arm and 130/70 mm Hg in the left arm. Physical examination shows a depression in the sternum and a grade 3/6 diastolic murmur at the right upper sternal border. A CT scan of the chest with contrast is shown. Which of the following is the most likely underlying cause of this patient's condition?
Q214
A 40-year-old man presents to the physician for a scheduled checkup. He was diagnosed with type 2 diabetes mellitus 5 years ago and has been taking his prescribed metformin daily, as prescribed. He also started exercising and has improved his diet. He has no particular complaints at the time. The patient has no other medical concerns and takes no medications. There is no family history of cardiovascular disease or diabetes. He does not smoke tobacco, drink alcohol, or use illicit drugs. Vitals are normal. There are no physical findings. His laboratory tests show:
Serum glucose (fasting) 149 mg/dL
Hemoglobin A1c 7.7 %
Serum electrolytes
Sodium 142 mEq/L
Potassium 3.9 mEq/L
Chloride 101 mEq/L
Serum creatinine 0.8 mg/dL
Blood urea nitrogen 9 mg/dL
Urinalysis
Glucose Negative
Ketones Negative
Leucocytes Negative
Nitrite Negative
Red blood cells (RBC) Negative
Casts Negative
Which of the following lipid profile abnormalities is most likely to be seen?
Q215
A 35-year-old woman presents with increased anxiety and a reeling sensation. Her complaint started 30 minutes ago with increased sweating and palpitations and is gradually worsening. On examination, the blood pressure was found to be 194/114 mm Hg. She had normal blood pressure at the local pharmacy 5 days ago. She currently works as an event manager and her job involves a lot of stress. The family history is significant for thyroid carcinoma in her father. Which of the following is most likely in this person?
Q216
A 69-year-old woman is brought to the emergency department because of fatigue and lethargy for 5 days. She has also had weakness and nausea for the last 3 days. She has sarcoidosis, major depressive disorder, and hypertension. She had a stroke 5 years ago. Current medications include aspirin, nifedipine, prednisolone, fluoxetine, and rosuvastatin, but she has not taken any of her medications for 7 days due to international travel. Her temperature is 36.1°C (96.9°F), pulse is 95/min, and blood pressure is 85/65 mm Hg. She is lethargic but oriented. Examination shows no other abnormalities. Her hemoglobin concentration is 13.4 g/dL and leukocyte count is 9,600/mm3. Both serum cortisol and ACTH levels are decreased. This patient is most likely to have which of the following additional laboratory abnormalities?
Q217
A 34-year-old G3P2103 with a past medical history of preeclampsia in her last pregnancy, HIV (CD4: 441/mm^3), and diabetes mellitus presents to her obstetrician for her first postpartum visit. She delivered her third child via C-section one week ago and reports that she is healing well from the surgery. She says that breastfeeding has been going well and that her baby has nearly regained his birth weight. The patient complains that she has been more tired than expected despite her efforts to sleep whenever her baby is napping. She relies on multiple iced coffees per day and likes to eat the ice after she finishes the drink. Her diet is otherwise unchanged, and she admits that she has not been getting outside to exercise as much as usual. Her home medications include metformin and her HAART regimen of dolutegravir, abacavir, and lamivudine. Her temperature is 98.9°F (37.2°C), blood pressure is 128/83 mmHg, pulse is 85/min, and respirations are 14/min. On physical exam, she is tired-appearing with conjunctival pallor.
Given this patient's clinical presentation suggestive of iron deficiency anemia, which of the following complications is she most at risk of developing?
Q218
A 68-year-old man comes to the emergency department because of a 1-week history of difficulty breathing. He has had recurrent palpitations over the past 2 years. During this time, he has also had several episodes of anxiety despite no change in his daily life. He has occasional sharp chest pain localized to the left upper sternal border. He has no abdominal pain or leg swelling. Two years ago, he had streptococcal pharyngitis, which was promptly treated with a 10-day course of penicillin. He has never traveled outside of the country. His temperature is 36.5°C (97.7°F), pulse is 82/min, and blood pressure is 140/85 mm Hg. Physical examination shows a 3/6 holosystolic murmur that is loudest at the apex and radiates to the axilla with a mid-systolic click. Bilateral fine crackles are heard on lung auscultation. Which of the following is the most likely cause of this patient's symptoms?
Q219
A 43-year-old woman comes to the physician for an annual health maintenance examination. On questioning, she has had fatigue and headaches for the last month. A few weeks ago, she had to have her wedding ring resized because it had become too small for her finger. She has mild persistent asthma and anxiety disorder. She drinks 2–3 glasses of red wine per night and has smoked one pack of cigarettes daily for 16 years. She works a desk job in accounting and has recently been working long hours due to an upcoming company merger. Her father has a history of a pituitary adenoma. Current medications include alprazolam, a fluticasone inhaler, and an albuterol inhaler. She is 160 cm (5 ft 3 in) tall and weighs 81.6 kg (180 lb); her BMI is 32 kg/m2. Her temperature is 37.2°C (99°F), pulse is 92/min, and blood pressure is 132/80 mm Hg. Examination shows no abnormalities. Fasting laboratory studies show:
Hemoglobin 13 g/dL
Serum
Na+ 135 mEq/L
K+
4.6 mEq/L
Cl- 105 mEq/L
HCO3- 22 mEq/L
Urea nitrogen 17 mg/dL
Glucose 160 mg/dL
Creatinine 0.9 mg/dL
Which of the following is the most likely underlying mechanism of this patient's hyperglycemia?
Q220
A 27-year-old woman comes to the physician because of a 1-year history of progressive shortness of breath. She is now unable to jog for more than 10 minutes without stopping to catch her breath. Cardiac examination shows a harsh systolic, crescendo-decrescendo murmur best heard at the lower left sternal border. The murmur increases in intensity when she moves from a squatting to a standing position and decreases when she clenches her fists. The lungs are clear to auscultation. Which of the following is the most likely cause of her condition?
Cardiology US Medical PG Practice Questions and MCQs
Question 211: A 52-year-old man presents to a medical clinic to establish care. He has no known chronic illnesses but has not seen a physician in over 20 years. He generally feels well but occasionally has shortness of breath when he jogs and exercises. He smokes 2-5 cigarettes per day and uses IV heroin “now and then.” Physical exam is unremarkable. ECG shows prominent QRS voltage and left axis deviation. Trans-thoracic echocardiogram shows mild concentric left ventricular hypertrophy but is otherwise normal. Which of the following is the most likely etiology of the echocardiogram findings?
A. Chronic obstructive pulmonary disease
B. Pulmonary hypertension
C. Aortic regurgitation
D. Systemic hypertension (Correct Answer)
E. Mitral stenosis
Explanation: ***Systemic hypertension***
- Chronic **systemic hypertension** is a common cause of **concentric left ventricular hypertrophy** due to increased afterload, which the left ventricle must overcome.
- The ECG findings of **prominent QRS voltage** and **left axis deviation** are also consistent with left ventricular hypertrophy, supporting chronic hypertension as the most likely cause.
*Chronic obstructive pulmonary disease*
- COPD primarily affects the lungs and typically leads to **right ventricular hypertrophy** (cor pulmonale) due to increased pulmonary vascular resistance, not left ventricular hypertrophy.
- While smoking is a risk factor for COPD, the patient's echocardiogram shows left, not right, heart changes.
*Pulmonary hypertension*
- Pulmonary hypertension causes increased afterload on the **right ventricle**, leading to **right ventricular hypertrophy**, not left ventricular hypertrophy.
- The echocardiogram specifically reports **left ventricular hypertrophy**.
*Aortic regurgitation*
- **Aortic regurgitation** leads to **volume overload** of the left ventricle, causing **eccentric left ventricular hypertrophy** (dilation along with thickening), not concentric hypertrophy.
- The echocardiogram finding of **concentric** (symmetric thickening without significant dilation) hypertrophy points away from aortic regurgitation.
*Mitral stenosis*
- **Mitral stenosis** causes increased pressure in the **left atrium** and **pulmonary circulation**, which can eventually lead to **right ventricular hypertrophy**, not left ventricular hypertrophy.
- It would not explain the **concentric left ventricular hypertrophy** noted in the echocardiogram.
Question 212: A 34-year-old woman comes to the physician because of a 3-month history of fatigue and a 4.5-kg (10-lb) weight loss despite eating more than usual. Her pulse is 115/min and blood pressure is 140/60 mm Hg. Physical examination shows warm, moist skin, and a diffuse, non-tender swelling over the anterior neck. Ophthalmologic examination shows swelling of the eyelids and proptosis bilaterally. Which of the following is the most likely cause of this patient's symptoms?
A. Constitutively active TSH receptor
B. Thyrotropin receptor autoantibodies (Correct Answer)
C. Parafollicular cell hyperplasia
D. Thyroid peroxidase autoantibodies
E. Nongranulomatous thyroid inflammation
Explanation: ***Thyrotropin receptor autoantibodies***
* The patient presents with symptoms of **hyperthyroidism** (fatigue, weight loss despite increased appetite, tachycardia, warm moist skin, diffuse goiter) along with **exophthalmos** (proptosis) and **eyelid swelling**.
* These clinical features are classic for **Graves' disease**, which is caused by antibodies stimulating the **TSH receptor** on thyroid follicular cells, leading to excessive thyroid hormone production.
*Constitutively active TSH receptor*
* While a constitutively active TSH receptor can lead to hyperthyroidism, it typically occurs in conditions like **toxic multinodular goiter** or **toxic adenoma**, or rarely, in a **hereditary form** of hyperthyroidism.
* It does **not explain the exophthalmos and eyelid swelling**, which are characteristic autoimmune manifestations of Graves' disease.
*Parafollicular cell hyperplasia*
* **Parafollicular cells** (C cells) produce calcitonin, and their hyperplasia is associated with **medullary thyroid carcinoma**.
* This condition primarily affects calcium metabolism and does **not cause hyperthyroidism or exophthalmos**.
*Thyroid peroxidase autoantibodies*
* **Thyroid peroxidase (TPO) antibodies** are characteristic of autoimmune thyroid diseases but are most strongly associated with **Hashimoto's thyroiditis**, which typically causes **hypothyroidism**.
* While TPO antibodies can be present in Graves' disease, the primary pathology driving the hyperthyroidism and ophthalmopathy is the **TSH receptor antibody**.
*Nongranulomatous thyroid inflammation*
* **Nongranulomatous inflammation** can occur in various thyroid conditions, including subacute thyroiditis (de Quervain's thyroiditis) or silent thyroiditis.
* These conditions usually present with a **transient phase of hyperthyroidism** followed by hypothyroidism, and they typically **do not cause ophthalmopathy or a diffuse, non-tender goiter** as seen here.
Question 213: A 43-year-old man from Chile comes to the physician because of a 1-day history of upper back pain and difficulty swallowing. He has had pain in his shoulder and knee joints over the past 10 years. He is 190 cm (6 ft 3 in) tall and weighs 70.3 kg (155 lb); BMI is 19.4 kg/m2. His blood pressure is 142/86 mm Hg in the right arm and 130/70 mm Hg in the left arm. Physical examination shows a depression in the sternum and a grade 3/6 diastolic murmur at the right upper sternal border. A CT scan of the chest with contrast is shown. Which of the following is the most likely underlying cause of this patient's condition?
A. Autoimmune valve damage
B. Atheroma formation
C. Protozoal infection
D. Cystic medial degeneration (Correct Answer)
E. Congenital aortic narrowing
Explanation: ***Cystic medial degeneration***
- This patient's tall stature, depressed sternum (**pectus excavatum**), and history of joint pain are suggestive of a **connective tissue disorder** like **Marfan syndrome**. The aortic aneurysm seen on CT and the **diastolic murmur** (indicating **aortic regurgitation**) are common cardiovascular manifestations of Marfan syndrome, which is often caused by **cystic medial degeneration** of the aorta.
- The **discrepancy in blood pressure** between the arms points to possible **aortic dissection**, a severe complication of aortic aneurysm linked to fragile vessel walls due to cystic medial degeneration.
*Autoimmune valve damage*
- While autoimmune conditions can cause valve damage (e.g., **rheumatic heart disease**), they typically present with specific inflammatory markers or symptoms not described here.
- The constellation of Marfanoid features and a large aortic aneurysm is more consistent with a hereditary connective tissue defect rather than primary autoimmune valvulitis.
*Atheroma formation*
- **Atherosclerosis** typically leads to **aortic stenosis** or occlusive disease, not primarily aortic root dilation and valvular incompetence as seen here.
- The patient's relatively low BMI and young age make severe atheroma formation an unlikely primary cause of significant aortic aneurysm and regurgitation.
*Protozoal infection*
- Certain protozoal infections, like **Chagas disease** (common in Chile), can cause cardiomyopathy and lead to apical aneurysms, but typically not a large **ascending aortic aneurysm** with associated Marfanoid features.
- Chagas disease more commonly affects the **myocardium** and causes **dilated cardiomyopathy**, rather than primary aortic root dilation and dissection.
*Congenital aortic narrowing*
- **Congenital aortic narrowing** (e.g., **aortic coarctation**) would manifest as blood pressure discrepancy but would not explain the large aortic aneurysm, joint pain, or Marfanoid habitus.
- Coarctation involves a localized narrowing, usually distal to the subclavian artery, and is not associated with the generalized connective tissue weakness seen in this patient.
Question 214: A 40-year-old man presents to the physician for a scheduled checkup. He was diagnosed with type 2 diabetes mellitus 5 years ago and has been taking his prescribed metformin daily, as prescribed. He also started exercising and has improved his diet. He has no particular complaints at the time. The patient has no other medical concerns and takes no medications. There is no family history of cardiovascular disease or diabetes. He does not smoke tobacco, drink alcohol, or use illicit drugs. Vitals are normal. There are no physical findings. His laboratory tests show:
Serum glucose (fasting) 149 mg/dL
Hemoglobin A1c 7.7 %
Serum electrolytes
Sodium 142 mEq/L
Potassium 3.9 mEq/L
Chloride 101 mEq/L
Serum creatinine 0.8 mg/dL
Blood urea nitrogen 9 mg/dL
Urinalysis
Glucose Negative
Ketones Negative
Leucocytes Negative
Nitrite Negative
Red blood cells (RBC) Negative
Casts Negative
Which of the following lipid profile abnormalities is most likely to be seen?
A. Normal lipid profile
B. Normal triglycerides, elevated LDL
C. Low HDL, elevated LDL
D. Elevated triglycerides, low HDL (Correct Answer)
E. Elevated HDL, low LDL
Explanation: ***Elevated triglycerides, low HDL***
- Patients with **type 2 diabetes mellitus** often exhibit **dyslipidemia** characterized by **elevated triglycerides** and **low high-density lipoprotein (HDL)** cholesterol, even with controlled glucose levels.
- This pattern is part of the **atherogenic dyslipidemia** frequently observed in insulin resistance, increasing cardiovascular risk.
*Normal lipid profile*
- Given the patient's diagnosis of **type 2 diabetes** and suboptimal **HbA1c of 7.7%** (target typically <7%), it is **unlikely** he would have a completely normal lipid profile due to the metabolic disturbances associated with insulin resistance.
- **Diabetes** itself is a risk factor for **dyslipidemia**, which mandates regular lipid screening even without overt symptoms.
*Normal triglycerides, elevated LDL*
- While **elevated LDL** cholesterol can occur in diabetes, a **normal triglyceride** level is **less typical** for diabetic dyslipidemia, which classically features hypertriglyceridemia.
- The most characteristic lipid abnormality in **type 2 diabetes** is often a combination of **high triglycerides** and **low HDL**, rather than isolated elevated LDL with normal triglycerides.
*Low HDL, elevated LDL*
- This option partially captures the typical dyslipidemia, as **low HDL** is characteristic. However, the most consistent abnormality alongside low HDL in diabetes is **elevated triglycerides**, often more prominent than just elevated LDL.
- While **elevated LDL** can occur, the combined pattern of **low HDL** and **elevated triglycerides** is more specific for **diabetic dyslipidemia**.
*Elevated HDL, low LDL*
- This lipid profile is generally considered **protective against cardiovascular disease** and is the **opposite** of what is typically seen in patients with **type 2 diabetes**.
- **Elevated HDL** and **low LDL** would be a favorable lipid profile, which is inconsistent with the metabolic derangements associated with diabetes.
Question 215: A 35-year-old woman presents with increased anxiety and a reeling sensation. Her complaint started 30 minutes ago with increased sweating and palpitations and is gradually worsening. On examination, the blood pressure was found to be 194/114 mm Hg. She had normal blood pressure at the local pharmacy 5 days ago. She currently works as an event manager and her job involves a lot of stress. The family history is significant for thyroid carcinoma in her father. Which of the following is most likely in this person?
A. Increased urine metanephrines (Correct Answer)
B. Decreased C-peptide
C. Decreased hemoglobin
D. Decreased TSH levels
E. Increased serum serotonin
Explanation: ***Increased urine metanephrines***
- The patient's symptoms (anxiety, reeling sensation, sweating, palpitations, and paroxysmal hypertension) are highly suggestive of a **pheochromocytoma**, which is a tumor of the adrenal medulla that secretes catecholamines.
- **Metanephrines** (metabolism products of catecholamines) are often elevated in urine and plasma samples from patients with pheochromocytoma, making this the most likely finding.
*Decreased C-peptide*
- **Decreased C-peptide** levels are indicative of reduced endogenous insulin production, typically seen in type 1 diabetes, which does not align with the patient's acute presentation of paroxysmal hypertension and anxiety.
- Her symptoms are not consistent with **hypoglycemia** or **diabetes mellitus**.
*Decreased hemoglobin*
- **Decreased hemoglobin** indicates anemia, which would present with fatigue, pallor, and shortness of breath, not the acute hypertensive crisis and anxiety described.
- There is no clinical information in the vignette to suggest **blood loss** or **red blood cell destruction**.
*Decreased TSH levels*
- **Decreased TSH levels** would suggest hyperthyroidism, which can cause anxiety and palpitations, but the sudden onset and extreme hypertension (194/114 mm Hg) are more characteristic of a **catecholamine surge** than typical hyperthyroidism.
- While there is a family history of **thyroid carcinoma**, the acute presentation points away from purely thyroid-related issues as the primary cause.
*Increased serum serotonin*
- **Increased serum serotonin** is associated with carcinoid syndrome, which typically presents with flushing, diarrhea, bronchospasm, and valvular heart disease, not the predominant features of anxiety, palpitations, and paroxysmal hypertension seen in this patient.
- The symptoms are more consistent with an acute release of **catecholamines**, not serotonin.
Question 216: A 69-year-old woman is brought to the emergency department because of fatigue and lethargy for 5 days. She has also had weakness and nausea for the last 3 days. She has sarcoidosis, major depressive disorder, and hypertension. She had a stroke 5 years ago. Current medications include aspirin, nifedipine, prednisolone, fluoxetine, and rosuvastatin, but she has not taken any of her medications for 7 days due to international travel. Her temperature is 36.1°C (96.9°F), pulse is 95/min, and blood pressure is 85/65 mm Hg. She is lethargic but oriented. Examination shows no other abnormalities. Her hemoglobin concentration is 13.4 g/dL and leukocyte count is 9,600/mm3. Both serum cortisol and ACTH levels are decreased. This patient is most likely to have which of the following additional laboratory abnormalities?
A. Hyperglycemia
B. Hyperkalemia
C. Hyponatremia (Correct Answer)
D. Hypokalemia
E. Normal anion gap metabolic acidosis
Explanation: ***Hyponatremia***
- This patient has **secondary adrenal insufficiency** due to **HPA axis suppression** from chronic prednisolone use, precipitated by abrupt withdrawal after 7 days without medication.
- **Both decreased cortisol and ACTH** confirm secondary (central) adrenal insufficiency, distinguishing it from primary adrenal insufficiency where ACTH would be elevated.
- **Hyponatremia** develops due to **cortisol deficiency** impairing free water excretion, leading to dilutional hyponatremia—a hallmark laboratory finding in adrenal insufficiency.
- Clinical features include **fatigue, lethargy, hypotension, nausea, and weakness**, consistent with adrenal crisis.
*Hyperglycemia*
- While **glucocorticoids** cause hyperglycemia, **cortisol deficiency** in adrenal insufficiency leads to **impaired gluconeogenesis** and a tendency toward **hypoglycemia**, not hyperglycemia.
- The patient's presentation with hypotension and weakness is consistent with adrenal crisis, not hyperglycemia.
*Hyperkalemia*
- **Hyperkalemia** is characteristic of **primary adrenal insufficiency** (Addison's disease) due to **aldosterone deficiency** affecting the renin-angiotensin-aldosterone system.
- In **secondary adrenal insufficiency**, the hypothalamic-pituitary axis is suppressed but the **renin-angiotensin-aldosterone system remains intact**, so aldosterone secretion is preserved and significant hyperkalemia does not occur.
*Hypokalemia*
- **Hypokalemia** is not a typical feature of adrenal insufficiency and is more commonly associated with diuretic use, primary hyperaldosteronism, or other conditions not present in this case.
- The patient's condition reflects cortisol deficiency with preserved aldosterone function.
*Normal anion gap metabolic acidosis*
- **Normal anion gap metabolic acidosis** occurs in conditions like **renal tubular acidosis** or **diarrhea**, but is not a direct or common consequence of secondary adrenal insufficiency.
- The acute presentation with hypotension and electrolyte disturbance (hyponatremia) is the primary metabolic derangement in this case.
Question 217: A 34-year-old G3P2103 with a past medical history of preeclampsia in her last pregnancy, HIV (CD4: 441/mm^3), and diabetes mellitus presents to her obstetrician for her first postpartum visit. She delivered her third child via C-section one week ago and reports that she is healing well from the surgery. She says that breastfeeding has been going well and that her baby has nearly regained his birth weight. The patient complains that she has been more tired than expected despite her efforts to sleep whenever her baby is napping. She relies on multiple iced coffees per day and likes to eat the ice after she finishes the drink. Her diet is otherwise unchanged, and she admits that she has not been getting outside to exercise as much as usual. Her home medications include metformin and her HAART regimen of dolutegravir, abacavir, and lamivudine. Her temperature is 98.9°F (37.2°C), blood pressure is 128/83 mmHg, pulse is 85/min, and respirations are 14/min. On physical exam, she is tired-appearing with conjunctival pallor.
Given this patient's clinical presentation suggestive of iron deficiency anemia, which of the following complications is she most at risk of developing?
A. Iron deficiency anemia
B. Sideroblastic anemia
C. Megaloblastic anemia
D. Hemolytic anemia
E. Restless legs syndrome (Correct Answer)
Explanation: ***Restless legs syndrome***
- **Iron deficiency anemia** is a recognized cause of **restless legs syndrome** (RLS), where the patient experiences an irresistible urge to move their legs, often accompanied by uncomfortable sensations.
- Patients with RLS often report **pica** (craving non-nutritive substances like ice), which this patient exhibits, further strengthening the association with iron deficiency.
*Iron deficiency anemia*
- This option is already presented in the question, as the patient's symptoms are described as "suggestive of **iron deficiency anemia**."
- The question asks for a **complication** of iron deficiency anemia, not the condition itself.
*Sideroblastic anemia*
- This is a type of anemia caused by the body's inability to incorporate iron into hemoglobin, leading to an accumulation of iron in the mitochondria of red blood cell precursors (sideroblasts).
- While it involves iron metabolism, it's typically due to **genetic defects**, **myelodysplastic syndromes**, or **toxins** (e.g., lead, alcohol), none of which are suggested here.
*Megaloblastic anemia*
- This anemia results from **impaired DNA synthesis**, leading to large, immature red blood cells.
- It is most commonly caused by **vitamin B12 deficiency** or **folate deficiency**, and is not directly associated with iron deficiency.
*Hemolytic anemia*
- This is characterized by the **destruction of red blood cells** before their normal lifespan.
- It can be caused by various factors like **autoimmune disorders**, **inherited red blood cell defects**, or **infections**, but there's no indication of increased red blood cell destruction in this patient.
Question 218: A 68-year-old man comes to the emergency department because of a 1-week history of difficulty breathing. He has had recurrent palpitations over the past 2 years. During this time, he has also had several episodes of anxiety despite no change in his daily life. He has occasional sharp chest pain localized to the left upper sternal border. He has no abdominal pain or leg swelling. Two years ago, he had streptococcal pharyngitis, which was promptly treated with a 10-day course of penicillin. He has never traveled outside of the country. His temperature is 36.5°C (97.7°F), pulse is 82/min, and blood pressure is 140/85 mm Hg. Physical examination shows a 3/6 holosystolic murmur that is loudest at the apex and radiates to the axilla with a mid-systolic click. Bilateral fine crackles are heard on lung auscultation. Which of the following is the most likely cause of this patient's symptoms?
A. Inflammatory valve degeneration
B. Ectopic production of serotonin
C. Myxomatous valve degeneration (Correct Answer)
D. Calcific valve degeneration
E. Overproduction of catecholamines
Explanation: ***Myxomatous valve degeneration***
- The presence of a **mid-systolic click** followed by a **holosystolic murmur** at the apex radiating to the axilla is highly characteristic of **mitral valve prolapse (MVP)** with **mitral regurgitation (MR)**.
- MVP is most commonly caused by **myxomatous degeneration** of the mitral valve leaflets, leading to their billowing into the left atrium during systole. The patient's recurrent palpitations, anxiety, and non-exertional chest pain are common symptoms associated with MVP, while difficulty breathing and crackles suggest **heart failure** from chronic MR.
*Inflammatory valve degeneration*
- **Inflammatory valve degeneration**, such as that seen in rheumatic heart disease, typically presents with a history of recurrent streptococcal infections leading to valvular scarring and dysfunction (e.g., mitral stenosis).
- While the patient had streptococcal pharyngitis, it was treated, and the clinical presentation with a mid-systolic click is more indicative of myxomatous changes rather than rheumatic inflammation.
*Ectopic production of serotonin*
- **Ectopic production of serotonin** occurs in settings like **carcinoid syndrome**, which typically involves flushing, diarrhea, bronchospasm, and can affect the right-sided heart valves primarily.
- The patient's symptoms are centered on left-sided heart issues and do not align with the broader systemic features of carcinoid syndrome.
*Calcific valve degeneration*
- **Calcific valve degeneration** commonly affects the **aortic valve** leading to **aortic stenosis** in older adults, characterized by a systolic ejection murmur heard at the right upper sternal border.
- It does not typically cause a mid-systolic click or affect the mitral valve in this manner, and the murmur description is inconsistent with aortic stenosis.
*Overproduction of catecholamines*
- **Overproduction of catecholamines**, as seen in conditions like **pheochromocytoma**, causes symptoms such as paroxysmal hypertension, palpitations, sweating, and anxiety.
- While some symptoms like palpitations and anxiety overlap, the specific cardiac murmur and signs of heart failure are not directly explained by catecholamine excess alone; a structural heart problem is more likely.
Question 219: A 43-year-old woman comes to the physician for an annual health maintenance examination. On questioning, she has had fatigue and headaches for the last month. A few weeks ago, she had to have her wedding ring resized because it had become too small for her finger. She has mild persistent asthma and anxiety disorder. She drinks 2–3 glasses of red wine per night and has smoked one pack of cigarettes daily for 16 years. She works a desk job in accounting and has recently been working long hours due to an upcoming company merger. Her father has a history of a pituitary adenoma. Current medications include alprazolam, a fluticasone inhaler, and an albuterol inhaler. She is 160 cm (5 ft 3 in) tall and weighs 81.6 kg (180 lb); her BMI is 32 kg/m2. Her temperature is 37.2°C (99°F), pulse is 92/min, and blood pressure is 132/80 mm Hg. Examination shows no abnormalities. Fasting laboratory studies show:
Hemoglobin 13 g/dL
Serum
Na+ 135 mEq/L
K+
4.6 mEq/L
Cl- 105 mEq/L
HCO3- 22 mEq/L
Urea nitrogen 17 mg/dL
Glucose 160 mg/dL
Creatinine 0.9 mg/dL
Which of the following is the most likely underlying mechanism of this patient's hyperglycemia?
A. Decreased insulin production
B. Adverse effect of medication
C. Stress
D. Insulin resistance (Correct Answer)
E. Hypersecretion of ACTH
Explanation: ***Insulin resistance***
- The patient's **obesity (BMI 32 kg/m2)**, **sedentary lifestyle**, and **fasting hyperglycemia** (glucose 160 mg/dL) indicate **insulin resistance**, which is the underlying mechanism of hyperglycemia in **type 2 diabetes**.
- The **ring resizing due to finger enlargement**, **fatigue**, **headaches**, and **family history of pituitary adenoma** raise suspicion for **acromegaly** (growth hormone excess), which also causes hyperglycemia through **insulin resistance** - growth hormone antagonizes insulin action at peripheral tissues.
- Regardless of whether this represents type 2 diabetes or acromegaly, **insulin resistance is the direct mechanism** causing the hyperglycemia in this patient.
*Decreased insulin production*
- Decreased insulin production is characteristic of **type 1 diabetes** or late-stage type 2 diabetes with beta-cell exhaustion.
- The patient's **obesity** and typical metabolic risk factors suggest **insulin resistance** rather than decreased production as the primary mechanism.
- No clinical features suggest autoimmune destruction or significant pancreatic damage.
*Adverse effect of medication*
- The patient's medications (**alprazolam**, **fluticasone inhaler**, **albuterol**) are unlikely to cause significant fasting hyperglycemia.
- While high-dose systemic **corticosteroids** can cause hyperglycemia, **inhaled fluticasone** at typical asthma doses has minimal systemic absorption and is not a common cause of sustained hyperglycemia.
- **Alprazolam** and **albuterol** do not typically cause hyperglycemia.
*Stress*
- **Acute stress** can transiently elevate blood glucose through counter-regulatory hormones (cortisol, catecholamines).
- However, the **fasting glucose of 160 mg/dL** suggests a chronic metabolic derangement rather than acute stress response alone.
- Work-related stress may be a contributing factor but is not the primary underlying mechanism.
*Hypersecretion of ACTH*
- **ACTH hypersecretion** (Cushing's disease) causes excess cortisol production, leading to hyperglycemia, weight gain, and fatigue.
- This patient lacks classic features of Cushing's syndrome: **central obesity with thin extremities**, **moon facies**, **buffalo hump**, **purple striae**, **skin thinning**, or **easy bruising**.
- While the patient is obese, the distribution appears generalized rather than the characteristic centripetal pattern of Cushing's syndrome.
Question 220: A 27-year-old woman comes to the physician because of a 1-year history of progressive shortness of breath. She is now unable to jog for more than 10 minutes without stopping to catch her breath. Cardiac examination shows a harsh systolic, crescendo-decrescendo murmur best heard at the lower left sternal border. The murmur increases in intensity when she moves from a squatting to a standing position and decreases when she clenches her fists. The lungs are clear to auscultation. Which of the following is the most likely cause of her condition?
A. Myosin heavy chain defect (Correct Answer)
B. CTG trinucleotide repeats
C. Dystrophin defect
D. GAA trinucleotide repeats
E. Fibrillin-1 defect
Explanation: ***Myosin heavy chain defect***
- The clinical presentation of **progressive shortness of breath**, a **harsh systolic crescendo-decrescendo murmur** that increases with standing and decreases with handgrip, is highly indicative of **hypertrophic cardiomyopathy (HCM)**.
- HCM is most commonly caused by genetic mutations affecting **sarcomeric proteins**, with mutations in the **beta-myosin heavy chain gene** being the most frequent.
*CTG trinucleotide repeats*
- **CTG trinucleotide repeats** are characteristic of **myotonic dystrophy type 1**, a multisystem disorder.
- While myotonic dystrophy can cause cardiac involvement (e.g., conduction abnormalities, dilated cardiomyopathy), it does not typically present with the classic murmur and dynamic changes seen in **HCM**.
*Dystrophin defect*
- A **dystrophin defect** is responsible for **Duchenne** and **Becker muscular dystrophies**, which primarily affect skeletal muscle.
- These conditions can lead to **dilated cardiomyopathy**, but not the type of obstructive outflow murmur associated with **HCM**.
*GAA trinucleotide repeats*
- **GAA trinucleotide repeats** are associated with **Friedreich ataxia**, a neurodegenerative disorder that can cause **hypertrophic cardiomyopathy** in up to 65% of patients.
- However, Friedreich ataxia presents with prominent **neurological symptoms** including progressive **ataxia, dysarthria, areflexia**, and loss of position/vibration sense, which are absent in this patient.
- The isolated cardiac presentation with no neurological findings points to **primary HCM** due to sarcomeric protein mutations rather than syndromic forms.
*Fibrillin-1 defect*
- A **fibrillin-1 defect** causes **Marfan syndrome**, a connective tissue disorder.
- Cardiac manifestations typically include **aortic root dilation** and **mitral valve prolapse**, not obstructive hypertrophic cardiomyopathy with the described murmur characteristics.