A 69-year-old man presents for a general follow up appointment. He states that he is doing well and wants to be sure he is healthy. The patient’s past medical history is significant for type II diabetes mellitus, peripheral vascular disease, and hypertension. His current medications include metformin, glyburide, lisinopril, metoprolol and hydrochlorothiazide. His blood pressure is 130/90 mmHg and pulse is 80/min. A fasting lipid panel was performed last week demonstrating an LDL of 85 mg/dL and triglycerides of 160 mg/dL. The patient states that he has not experienced any symptoms since his last visit. The patient’s blood glucose at this visit is 100 mg/dL. Which of the following is recommended in this patient?
Q1062
A 16-year-old boy with a history of severe, persistent asthma presents to the emergency department with severe shortness of breath and cough. He states that he was outside playing basketball with his friends, forgot to take his inhaler, and began to have severe difficulty breathing. On exam, he is in clear respiratory distress with decreased air movement throughout all lung fields. He is immediately treated with beta-agonists which markedly improve his symptoms. Prior to treatment, which of the following was most likely observed in this patient?
Q1063
A 68-year-old woman is brought to the emergency department by ambulance after she was found down by her daughter. She lives alone in her apartment so it is unclear when she began to develop symptoms. Her medical history is significant for cardiac arrhythmias, diabetes, pericarditis, and a stroke 2 years ago. On presentation her temperature is 98.1°F (36.7°C), blood pressure is 88/51 mmHg, pulse is 137/min, and respirations are 18/min. On physical exam her skin is cold and clammy. If special tests were obtained, they would reveal dramatically decreased pulmonary capillary wedge pressure, increased systemic vascular resistance, and mildly decreased cardiac output. Which of the following treatments would most directly target the cause of this patient's low blood pressure?
Q1064
A 72-year-old man comes to the physician because of fatigue and a 5-kg (11-lb) weight loss over the past 6 months despite a good appetite. He takes no medications. He does not smoke or use illicit drugs. Physical examination shows hepatosplenomegaly and diffuse, nontender lymphadenopathy. Laboratory studies show a hemoglobin concentration of 11 g/dL and a leukocyte count of 16,000/mm3. A direct antiglobulin (Coombs) test is positive. A photomicrograph of a peripheral blood smear is shown. Which of the following is the most likely diagnosis?
Q1065
A 72-year-old woman with a medical history significant for chronic kidney disease stage 4, hypertension, and type 2 diabetes mellitus, presents to the office for a scheduled visit. During her last visit, the physician started discussing with her the possibility of starting her on dialysis for her chronic kidney disease. The patient has no complaints about her health and enjoys spending time with her family. At presentation, she is afebrile; the blood pressure is 139/89 mm Hg and the heart rate is 80/min. On physical examination, her pulses are bounding, the complexion is pale, she has a grade ⅙ holosystolic murmur, breath sounds remain clear, and 2+ pedal edema to the knee. The measurement of which of the following laboratory values is most appropriate to screen for renal osteodystrophy in this patient?
Q1066
A 44-year-old woman presents to her physician’s office for weakness. She reports having some difficulty placing books on a high shelf and getting up from a seated position. She denies muscle pain or any new rashes. She has noticed a tremor that is worse with action and has been having trouble falling asleep and staying asleep. She has lost approximately 10 pounds unintentionally over the course of 2 months. Medical history is significant for type I diabetes mellitus managed with an insulin pump. Family history is notable for systemic lupus erythematosus in her mother and panic disorder in the father. Her temperature is 98.6°F (37 °C), blood pressure is 140/85 mmHg, pulse is 102/min, and respirations are 17/min. On physical exam, she is mildly diaphoretic and restless, she has notable lid retraction, and her hair is thin. She has 4/5 strength in the proximal upper and lower extremities. Biceps and patellar tendon reflexes are 3+. Which of the following laboratory findings are most likely present in this patient?
Q1067
A 70-year-old woman presents to the office for a yearly physical. She states she has recently started experiencing pain in her legs and her back. Last year, she experienced a fracture of her left arm while trying to lift groceries. The patient states that she does not consume any dairy and does not go outside often because of the pain in her legs and back. Of note, she takes carbamazepine for seizures. On exam, her vitals are within normal limits. You suspect the patient might have osteomalacia. Testing for which of the following is the next best step to confirm your suspicion?
Q1068
A 22-year-old man is brought to the emergency department by ambulance 1 hour after a motor vehicle accident. He did not require any circulatory resuscitation at the scene, but he was intubated because he was unresponsive. He has no history of serious illnesses. He is on mechanical ventilation with no sedation. His blood pressure is 121/62 mm Hg, the pulse is 68/min, and the temperature is 36.5°C (97.7°F). His Glasgow coma scale (GCS) is 3. Early laboratory studies show no abnormalities. A search of the state donor registry shows that he has registered as an organ donor. Which of the following is the most appropriate next step in evaluation?
Q1069
A 47-year-old woman presents to the clinic complaining of difficulty swallowing that started 1 month ago. The patient also reports a weight loss of 10 lbs during this time, without a change in her appetite. She denies fatigue, cough, hoarseness, pain, or hemoptysis. The patient has a history of childhood lymphoma, which was treated with radiation. She takes no medications. She has smoked 1 pack of cigarettes per day since she was 25 years old. Her physical exam is notable for a palpable nodule on the right side of the thyroid. An ultrasound is performed, which confirms a 1.2 cm hyperechoic nodule in the right lobe. Thyroid function labs are drawn and shown below:
Serum TSH: 0.2 mU/L
Serum thyroxine (T4): 187 nmol/L
Serum triiodothyronine (T3): 3.3 nmol/L
Which of the following is the next best step in management?
Q1070
A 52-year-old woman presents to her primary care physician with symptoms of heat intolerance, unintentional weight loss, feelings of anxiety, and excessive energy that hinder her from falling asleep at night. On physical exam, the patient is found to have mildly protuberant eyes bilaterally as well as discoloration and swelling of her shins. Which of the following lab results would most likely be present in this patient?
Cardiology US Medical PG Practice Questions and MCQs
Question 1061: A 69-year-old man presents for a general follow up appointment. He states that he is doing well and wants to be sure he is healthy. The patient’s past medical history is significant for type II diabetes mellitus, peripheral vascular disease, and hypertension. His current medications include metformin, glyburide, lisinopril, metoprolol and hydrochlorothiazide. His blood pressure is 130/90 mmHg and pulse is 80/min. A fasting lipid panel was performed last week demonstrating an LDL of 85 mg/dL and triglycerides of 160 mg/dL. The patient states that he has not experienced any symptoms since his last visit. The patient’s blood glucose at this visit is 100 mg/dL. Which of the following is recommended in this patient?
A. Begin statin therapy (Correct Answer)
B. Increase lisinopril dose
C. Increase HCTZ dose
D. Discontinue metoprolol and start propranolol
E. Increase metformin dose
Explanation: **Begin statin therapy**
- The patient has **multiple risk factors** for cardiovascular disease including type 2 diabetes, peripheral vascular disease, and hypertension. His LDL-C of 85 mg/dL, while not excessively high, still warrants statin therapy given his high-risk profile, as guidelines recommend statin use in these patients to reduce cardiovascular events.
- Patients with a history of **atherosclerotic cardiovascular disease (ASCVD)**, which includes peripheral vascular disease, should be on a **high-intensity statin** regardless of their baseline LDL-C level, unless contraindicated.
*Increase lisinopril dose*
- The patient's blood pressure is 130/90 mmHg. While his systolic pressure is within an acceptable range for a patient with diabetes, his **diastolic pressure of 90 mmHg is slightly elevated**, but a single reading may not warrant an immediate dosage increase.
- Lisinopril is an ACE inhibitor and is already at an appropriate dose given the blood pressure. Further increasing the dose without evidence of persistent high blood pressure or other compelling indications is not the primary next step.
*Increase HCTZ dose*
- The patient is already on hydrochlorothiazide (HCTZ) for hypertension. His blood pressure is 130/90 mmHg, which is **not severely elevated**, and his medications are generally well-controlled.
- Increasing the dose of HCTZ might lead to side effects such as **electrolyte imbalances** (e.g., hypokalemia, hyponatremia) or worsening glucose control, and is not the most pressing intervention.
*Discontinue metoprolol and start propranolol*
- Metoprolol is a **selective beta-1 blocker** and is appropriate for this patient's hypertension and cardiac health, especially given his history.
- Propranolol is a **non-selective beta-blocker** and is generally less preferred in patients with diabetes or peripheral vascular disease due to potential masking of hypoglycemia symptoms and worsening peripheral circulation.
*Increase metformin dose*
- The patient's blood glucose is 100 mg/dL, indicating **good glycemic control** on his current regimen of metformin and glyburide.
- There is no indication to increase the metformin dose as his current glucose levels are within the target range, and increasing it could risk **hypoglycemia**, especially with concomitant glyburide.
Question 1062: A 16-year-old boy with a history of severe, persistent asthma presents to the emergency department with severe shortness of breath and cough. He states that he was outside playing basketball with his friends, forgot to take his inhaler, and began to have severe difficulty breathing. On exam, he is in clear respiratory distress with decreased air movement throughout all lung fields. He is immediately treated with beta-agonists which markedly improve his symptoms. Prior to treatment, which of the following was most likely observed in this patient?
A. Kussmaul's sign
B. Pulsus paradoxus (Correct Answer)
C. Friction rub
D. Inspiratory stridor
E. Increased breath sounds
Explanation: ***Pulsus paradoxus***
* **Pulsus paradoxus** is a classic sign of **severe asthma exacerbation**, characterized by an abnormally large decrease in **systolic blood pressure** during inspiration.
* The marked improvement with **beta-agonists** confirms the likely diagnosis of acute severe asthma, making pulsus paradoxus a highly probable finding before treatment.
*Kussmaul's sign*
* **Kussmaul's sign** is a paradoxical rise in **jugular venous pressure (JVP)** during inspiration, typically seen in conditions like **constrictive pericarditis** or **right heart failure**.
* It is not associated with acute asthma exacerbations.
*Friction rub*
* A **friction rub** is a leathery or grating sound heard on auscultation, indicative of inflammation of the **pleura** (pleurisy) or **pericardium** (pericarditis).
* It is not a typical finding in asthma and would suggest an alternative or co-existing pathology.
*Inspiratory stridor*
* **Inspiratory stridor** is a harsh, high-pitched sound primarily heard during inspiration, caused by **upper airway obstruction** (e.g., croup, epiglottitis, foreign body aspiration).
* While severe shortness of breath is present, the symptom relief with beta-agonists points to **lower airway obstruction** characteristic of asthma rather than upper airway issues.
*Increased breath sounds*
* In **severe asthma exacerbations**, there is significant **bronchoconstriction** and **air trapping**, leading to markedly **decreased or absent breath sounds** on auscultation, not increased.
* Increased breath sounds might be heard in consolidation (pneumonia) or early stages of bronchiole inflammation, but not in severe asthma distress.
Question 1063: A 68-year-old woman is brought to the emergency department by ambulance after she was found down by her daughter. She lives alone in her apartment so it is unclear when she began to develop symptoms. Her medical history is significant for cardiac arrhythmias, diabetes, pericarditis, and a stroke 2 years ago. On presentation her temperature is 98.1°F (36.7°C), blood pressure is 88/51 mmHg, pulse is 137/min, and respirations are 18/min. On physical exam her skin is cold and clammy. If special tests were obtained, they would reveal dramatically decreased pulmonary capillary wedge pressure, increased systemic vascular resistance, and mildly decreased cardiac output. Which of the following treatments would most directly target the cause of this patient's low blood pressure?
A. Vasopressors
B. Intravenous fluids (Correct Answer)
C. Antibiotic administration
D. Relieve obstruction
E. Intravenous inotropes
Explanation: ***Intravenous fluids***
- The patient exhibits signs of **hypovolemic shock**, including **hypotension** (BP 88/51 mmHg), **tachycardia** (pulse 137/min), and **cold, clammy skin**. The dramatically decreased **pulmonary capillary wedge pressure (PCWP)** indicates low preload, which is characteristic of hypovolemia.
- Administration of intravenous fluids directly addresses the underlying cause of this patient's low blood pressure by increasing intravascular volume, thereby improving **cardiac preload** and ultimately **cardiac output** and blood pressure.
*Vasopressors*
- While vasopressors can temporarily increase blood pressure by causing **vasoconstriction**, they do not address the root cause of hypovolemic shock, which is insufficient circulating blood volume.
- Using vasopressors without adequate fluid resuscitation in hypovolemic shock can lead to further **organ hypoperfusion** due to increased afterload on an already compromised heart.
*Antibiotic administration*
- Although the patient's presentation with hypotension and tachycardia could raise suspicion for **sepsis**, there is no explicit evidence of infection presented (e.g., fever, focal source).
- The **decreased PCWP** points more strongly towards hypovolemic shock rather than septic shock, where PCWP can be variable or even normal/elevated.
*Relieve obstruction*
- Obstruction, such as in **cardiac tamponade** or **pulmonary embolism**, can cause obstructive shock, which presents with hypotension.
- However, the dramatically **decreased PCWP** is not typically seen in obstructive shock, where PCWP would likely be normal or elevated due to impedance to cardiac filling or outflow.
*Intravenous inotropes*
- **Inotropes** like dobutamine increase myocardial contractility and are primarily indicated in **cardiogenic shock** or severe heart failure with reduced ejection fraction to improve cardiac output.
- While cardiac output is mildly decreased, the primary issue is reduced preload as indicated by the very low PCWP, making fluid resuscitation a more appropriate initial step than directly increasing contractility.
Question 1064: A 72-year-old man comes to the physician because of fatigue and a 5-kg (11-lb) weight loss over the past 6 months despite a good appetite. He takes no medications. He does not smoke or use illicit drugs. Physical examination shows hepatosplenomegaly and diffuse, nontender lymphadenopathy. Laboratory studies show a hemoglobin concentration of 11 g/dL and a leukocyte count of 16,000/mm3. A direct antiglobulin (Coombs) test is positive. A photomicrograph of a peripheral blood smear is shown. Which of the following is the most likely diagnosis?
A. Acute myelogenous leukemia
B. Chronic lymphocytic leukemia (Correct Answer)
C. Chronic myelogenous leukemia
D. Hemophagocytic lymphohistiocytosis
E. Follicular lymphoma
Explanation: ***Chronic lymphocytic leukemia***
- The photomicrograph shows numerous small, mature-appearing lymphocytes with dense nuclei, consistent with **chronic lymphocytic leukemia (CLL)**. The clinical picture of **fatigue, weight loss, hepatosplenomegaly, and diffuse lymphadenopathy** in an elderly patient is also highly suggestive of CLL.
- The positive direct antiglobulin (Coombs) test indicates **autoimmune hemolytic anemia**, which is a common paraneoplastic complication of CLL due to dysregulated B-cell function leading to antibody production against red blood cells. The **leukocyte count of 16,000/mm³ with lymphocytosis** is also characteristic.
*Acute myelogenous leukemia*
- This condition presents with a high percentage of **myeloblasts** (immature myeloid cells) in the peripheral blood and bone marrow, which are not depicted in the photomicrograph.
- While AML can cause fatigue and weight loss, the key features like **diffuse lymphadenopathy** and **Coombs-positive anemia** are not typical primary manifestations.
*Chronic myelogenous leukemia*
- CML is characterized by a high white blood cell count with a **left shift**, meaning the presence of myeloid precursors at various stages of maturation (myelocytes, metamyelocytes, bands), and often very high platelet counts.
- The peripheral smear in CML would show a predominance of **granulocytes and their precursors**, often with a very large spleen, but not primarily mature lymphocytes or autoimmune hemolytic anemia as shown.
*Hemophagocytic lymphohistiocytosis*
- HLH presents with fever, hepatosplenomegaly, cytopenias, and often neurologic symptoms, but the hallmark is **hemophagocytosis** (histiocytes engulfing blood cells) in the bone marrow and other organs.
- The peripheral blood smear would not typically show a predominance of mature lymphocytes or evidence of autoimmune hemolytic anemia.
*Follicular lymphoma*
- Follicular lymphoma is a non-Hodgkin lymphoma that typically presents with **painless lymphadenopathy** and can cause B symptoms (fever, weight loss, night sweats).
- While it can cause lymphadenopathy and fatigue, it is primarily a lymph node disease and typically does not manifest with a **marked peripheral blood lymphocytosis** or **autoimmune hemolytic anemia** as prominently as CLL.
Question 1065: A 72-year-old woman with a medical history significant for chronic kidney disease stage 4, hypertension, and type 2 diabetes mellitus, presents to the office for a scheduled visit. During her last visit, the physician started discussing with her the possibility of starting her on dialysis for her chronic kidney disease. The patient has no complaints about her health and enjoys spending time with her family. At presentation, she is afebrile; the blood pressure is 139/89 mm Hg and the heart rate is 80/min. On physical examination, her pulses are bounding, the complexion is pale, she has a grade ⅙ holosystolic murmur, breath sounds remain clear, and 2+ pedal edema to the knee. The measurement of which of the following laboratory values is most appropriate to screen for renal osteodystrophy in this patient?
A. Erythrocyte sedimentation rate
B. Serum vitamin B-12 level
C. Serum C-reactive protein level
D. Serum thyroid-stimulating hormone level
E. Serum intact parathyroid hormone level (Correct Answer)
Explanation: ***Serum intact parathyroid hormone level***
- **Renal osteodystrophy**, a common complication of **chronic kidney disease (CKD)** stage 4 and 5, is primarily caused by secondary hyperparathyroidism.
- **Intact parathyroid hormone (iPTH)** is critical in diagnosing and monitoring this condition, as elevated levels indicate impaired mineral and bone metabolism due to failing kidneys.
*Erythrocyte sedimentation rate*
- **Erythrocyte sedimentation rate (ESR)** is a general marker of inflammation and is not specific for renal osteodystrophy.
- While CKD can be associated with inflammation, ESR does not directly assess mineral and bone disorders.
*Serum vitamin B-12 level*
- **Vitamin B-12** deficiency can cause anemia and neurological symptoms, but it is not directly involved in the pathogenesis or diagnosis of renal osteodystrophy.
- This test would be more relevant if the patient presented with symptoms of **pernicious anemia** or neuropathy.
*Serum C-reactive protein level*
- **C-reactive protein (CRP)**, like ESR, is a general **inflammatory marker** and does not provide specific information about bone health or mineral metabolism in CKD.
- High CRP levels might indicate infection or systemic inflammation but are not used to screen for renal osteodystrophy.
*Serum thyroid-stimulating hormone level*
- **Thyroid-stimulating hormone (TSH)** assesses **thyroid function**, which is distinct from renal osteodystrophy.
- Thyroid disorders can impact bone health, but TSH is not the primary screening test for bone disease related to CKD.
Question 1066: A 44-year-old woman presents to her physician’s office for weakness. She reports having some difficulty placing books on a high shelf and getting up from a seated position. She denies muscle pain or any new rashes. She has noticed a tremor that is worse with action and has been having trouble falling asleep and staying asleep. She has lost approximately 10 pounds unintentionally over the course of 2 months. Medical history is significant for type I diabetes mellitus managed with an insulin pump. Family history is notable for systemic lupus erythematosus in her mother and panic disorder in the father. Her temperature is 98.6°F (37 °C), blood pressure is 140/85 mmHg, pulse is 102/min, and respirations are 17/min. On physical exam, she is mildly diaphoretic and restless, she has notable lid retraction, and her hair is thin. She has 4/5 strength in the proximal upper and lower extremities. Biceps and patellar tendon reflexes are 3+. Which of the following laboratory findings are most likely present in this patient?
A. Anti-Mi-2 antibody positivity
B. Decreased thyroid-stimulating hormone (Correct Answer)
C. Anti-nuclear antibody positivity
D. Increased erythrocyte sedimentation rate
E. Normal laboratory results
Explanation: **Decreased thyroid-stimulating hormone**
- The patient exhibits classic symptoms of **hyperthyroidism**, including unintended weight loss, heat intolerance (diaphoresis), fine tremor, insomnia, tachycardia (pulse 102/min), and proximal muscle weakness. Lid retraction and thin hair are also characteristic signs.
- In primary hyperthyroidism, the excessive production of thyroid hormones (T3 and T4) by the thyroid gland suppresses the pituitary's release of TSH, leading to a **decreased TSH level**.
*Anti-Mi-2 antibody positivity*
- **Anti-Mi-2 antibodies** are specific to **dermatomyositis**, which typically presents with a characteristic dermatological rash (e.g., heliotrope rash, Gottron papules) in addition to proximal muscle weakness. The patient explicitly denies new rashes.
- While proximal weakness is present, the absence of skin findings and the presence of significant hyperthyroid symptoms make dermatomyositis less likely.
*Anti-nuclear antibody positivity*
- **Anti-nuclear antibodies (ANAs)** are often positive in **autoimmune connective tissue diseases** like systemic lupus erythematosus (SLE), Sjogren's syndrome, and scleroderma. While the mother had SLE, the patient's constellation of symptoms points more directly to thyroid dysfunction.
- While ANA can be positive in autoimmune thyroid disease, it's not the most direct or specific laboratory finding for the dominant clinical picture presented.
*Increased erythrocyte sedimentation rate*
- An **increased ESR** is a non-specific marker of **inflammation** and can be elevated in various conditions, including infections, autoimmune diseases, and certain cancers.
- While ESR can be elevated in some cases of hyperthyroidism, it is not as specific or as direct a diagnostic marker for the condition as thyroid hormone levels themselves.
*Normal laboratory results*
- Given the clear and numerous signs and symptoms of a pathological process, particularly **hyperthyroidism**, it is highly unlikely that all laboratory results would be normal.
- The constellation of symptoms like weight loss, tremor, palpitations, insomnia, and muscle weakness strongly indicates a significant underlying medical condition requiring laboratory investigation.
Question 1067: A 70-year-old woman presents to the office for a yearly physical. She states she has recently started experiencing pain in her legs and her back. Last year, she experienced a fracture of her left arm while trying to lift groceries. The patient states that she does not consume any dairy and does not go outside often because of the pain in her legs and back. Of note, she takes carbamazepine for seizures. On exam, her vitals are within normal limits. You suspect the patient might have osteomalacia. Testing for which of the following is the next best step to confirm your suspicion?
A. Vitamin D2 (ergocalciferol)
B. 25-hydroxyvitamin D (Correct Answer)
C. Pre-vitamin D3
D. 1,25-hydroxyvitamin D
E. 7-dehydrocholesterol
Explanation: ***25-hydroxyvitamin D***
- This is the **best initial test** for evaluating vitamin D deficiency, which leads to **osteomalacia**.
- It reflects the circulating levels of vitamin D and is the **most accurate indicator** of the body's vitamin D stores.
*Vitamin D2 (ergocalciferol)*
- While D2 is a form of vitamin D, measuring only D2 levels is **not sufficient** to assess overall vitamin D status.
- The standard test measures total circulating vitamin D, which includes both D2 and D3, but specifically **25-hydroxyvitamin D** reflects the active usable form.
*Pre-vitamin D3*
- **Pre-vitamin D3** is a precursor molecule formed in the skin from 7-dehydrocholesterol upon UV exposure, and it rapidly isomerizes to vitamin D3.
- It is **not a stable measurable form** in the blood for assessing vitamin D status or diagnosing osteomalacia.
*1,25-hydroxyvitamin D*
- This is the **active hormonal form of vitamin D**, primarily regulated by parathyroid hormone (PTH) and kidney function.
- Levels can be normal or even elevated in early vitamin D deficiency due to increased PTH, making it **less reliable** for initial assessment of deficiency.
*7-dehydrocholesterol*
- **7-dehydrocholesterol** is a precursor molecule in the skin that is converted to pre-vitamin D3 by UV radiation.
- Measuring this precursor is **not clinically significant** for diagnosing osteomalacia or assessing vitamin D deficiency.
Question 1068: A 22-year-old man is brought to the emergency department by ambulance 1 hour after a motor vehicle accident. He did not require any circulatory resuscitation at the scene, but he was intubated because he was unresponsive. He has no history of serious illnesses. He is on mechanical ventilation with no sedation. His blood pressure is 121/62 mm Hg, the pulse is 68/min, and the temperature is 36.5°C (97.7°F). His Glasgow coma scale (GCS) is 3. Early laboratory studies show no abnormalities. A search of the state donor registry shows that he has registered as an organ donor. Which of the following is the most appropriate next step in evaluation?
A. Evaluation of brainstem reflexes (Correct Answer)
B. Brain MRI
C. Electroencephalography
D. Cerebral angiography
E. Apnea test
Explanation: ***Evaluation of brainstem reflexes***
- In a patient with a **Glasgow Coma Scale (GCS) of 3** and no response to noxious stimuli/sedation, assessment of **brainstem reflexes** is a critical step in determining brain death.
- This evaluation includes checking for pupillary light reflex, corneal reflex, vestibulo-ocular reflex (doll's eyes), oculocephalic reflex, and gag/cough reflexes to ascertain the complete absence of brainstem function.
*Brain MRI*
- While a brain MRI can provide detailed anatomical information regarding brain injury, it is **not the primary diagnostic test** for determining brain death.
- Brain death is a **clinical diagnosis** based on the irreversible loss of brain and brainstem function, which can be confirmed rapidly by clinical examination.
*Electroencephalography*
- **EEG** measures electrical activity in the brain and can show electrocerebral silence, which is consistent with brain death.
- However, EEG is **not always required** for the diagnosis of brain death and is often used as a confirmatory test in specific situations, such as when clinical examination is inconclusive or legal requirements necessitate it.
*Cerebral angiography*
- **Cerebral angiography** can demonstrate the absence of cerebral blood flow, which is a criterion for brain death.
- This is an **invasive procedure** and is generally reserved for situations where clinical examination tests are difficult to perform or interpret (e.g., severe facial trauma, drug intoxication), and is not the initial step.
*Apnea test*
- The **apnea test** is a critical component of the brain death evaluation, confirming the absence of spontaneous breathing response to hypercapnia.
- It is performed **after the absence of brainstem reflexes** has been established and all confounding factors (e.g., hypothermia, hypotension, sedatives) have been ruled out.
Question 1069: A 47-year-old woman presents to the clinic complaining of difficulty swallowing that started 1 month ago. The patient also reports a weight loss of 10 lbs during this time, without a change in her appetite. She denies fatigue, cough, hoarseness, pain, or hemoptysis. The patient has a history of childhood lymphoma, which was treated with radiation. She takes no medications. She has smoked 1 pack of cigarettes per day since she was 25 years old. Her physical exam is notable for a palpable nodule on the right side of the thyroid. An ultrasound is performed, which confirms a 1.2 cm hyperechoic nodule in the right lobe. Thyroid function labs are drawn and shown below:
Serum TSH: 0.2 mU/L
Serum thyroxine (T4): 187 nmol/L
Serum triiodothyronine (T3): 3.3 nmol/L
Which of the following is the next best step in management?
A. Radioactive iodine
B. Partial thyroidectomy
C. Fine needle aspiration (Correct Answer)
D. Levothyroxine
E. Thyroid scintigraphy
Explanation: ***Fine needle aspiration***
- This patient has several risk factors for **thyroid malignancy**, including a history of **radiation exposure** to the neck (for childhood lymphoma) and a palpable thyroid nodule associated with **dysphagia** and unexplained **weight loss**. Fine needle aspiration (FNA) is the best next step to evaluate for malignancy.
- The patient also presents with **hyperthyroidism** (low TSH, elevated T4), but the primary concern given the clinical picture is to rule out thyroid cancer.
- Per American Thyroid Association guidelines, FNA is indicated for any nodule in a patient with a history of head/neck radiation exposure.
*Radioactive iodine*
- Radioactive iodine ablation is used to treat **hyperthyroidism**, especially in cases of **Graves' disease** or toxic nodular goiter. While the patient has hyperthyroidism, the presence of a suspicious nodule warrants investigation for malignancy first.
- Administering radioactive iodine without first ruling out malignancy in a suspicious nodule could delay definitive treatment for cancer or complicate its management.
*Partial thyroidectomy*
- **Partial thyroidectomy** would be considered if the FNA results indicate malignancy or a highly suspicious follicular neoplasm.
- Performing surgery without a prior FNA would be premature, as many thyroid nodules are benign and do not require surgical intervention unless causing compressive symptoms or confirmed malignancy.
*Levothyroxine*
- **Levothyroxine** is used to treat **hypothyroidism** or to suppress TSH in cases of benign thyroid nodules or after thyroid cancer surgery.
- This patient is **hyperthyroid**, making exogenous levothyroxine inappropriate.
*Thyroid scintigraphy*
- **Thyroid scintigraphy** (radioactive iodine uptake scan) is useful in characterizing thyroid nodules as "hot" (functioning) or "cold" (non-functioning) in the context of hyperthyroidism.
- "Hot" nodules are rarely malignant, while "cold" nodules have a higher (though still relatively low) risk of malignancy. However, given the patient's strong risk factors for thyroid cancer and compressive symptoms, an FNA is more direct and informative for assessing malignancy than scintigraphy at this stage.
Question 1070: A 52-year-old woman presents to her primary care physician with symptoms of heat intolerance, unintentional weight loss, feelings of anxiety, and excessive energy that hinder her from falling asleep at night. On physical exam, the patient is found to have mildly protuberant eyes bilaterally as well as discoloration and swelling of her shins. Which of the following lab results would most likely be present in this patient?
A. Decreased serum TSH (Correct Answer)
B. Increased anti-mitochondrial antibodies
C. Decreased free T4
D. Increased serum TSH
E. Decreased anti-TSH receptor antibodies
Explanation: ***Decreased serum TSH***
- The patient's symptoms (heat intolerance, weight loss, anxiety, insomnia, protuberant eyes, pretibial myxedema) are classic for **hyperthyroidism**, specifically **Graves' disease**.
- In primary hyperthyroidism, the thyroid gland overproduces thyroid hormones (T3 and T4), which **negatively feedback** on the pituitary, leading to a decreased or **undetectable serum TSH**.
*Increased anti-mitochondrial antibodies*
- **Anti-mitochondrial antibodies (AMAs)** are the hallmark of **primary biliary cholangitis**, a chronic autoimmune liver disease.
- This condition presents with symptoms like **fatigue, pruritus, and jaundice**, which are not observed in this patient.
*Decreased free T4*
- A **decreased free T4** indicates **hypothyroidism**, where the thyroid gland produces insufficient thyroid hormones.
- This would present with symptoms opposite to those described, such as **cold intolerance, weight gain, fatigue, and bradycardia**.
*Decreased anti-TSH receptor antibodies*
- **Anti-TSH receptor antibodies (TRAb)** are characteristic of Graves' disease, and they are typically **stimulatory** (thyroid-stimulating immunoglobulins), meaning they mimic TSH and **increase** thyroid hormone production.
- A decrease in these antibodies would suggest a *reduction* in the autoimmune stimulation, which is inconsistent with the patient's active hyperthyroid state.
- In this patient with clear Graves' disease, these antibodies would be **elevated**, not decreased.
*Increased serum TSH*
- An **increased serum TSH** is indicative of **primary hypothyroidism**, where the pituitary gland attempts to stimulate an underactive thyroid.
- This would lead to symptoms of **fatigue, weight gain, cold intolerance, and bradycardia**, which contradict the patient's presentation.
