Case-based MCQ

The correct answer is A. This patient is suffering from an acute kidney injury (AKI) due to pigment nephropathy from rhabdomyolysis. A urine dipstick test for blood with positive findings in the absence of red blood cells (RBCs) indicates myoglobinuria. This should automatically suggest rhabdomyolysis. A creatine kinase (CK) level can confirm that the patient has rhabdomyolysis from protein/calorie malnutrition. She has been losing weight and is weak, and her albumin level is low, which confirms a decreased oral intake. CK levels rise within 12 hours of muscle injury, peak in 24-36 hours, and decrease at a rate of 30-40% per day. The serum half-life of CK is approximately 36 hours. Total CK elevation is a sensitive but nonspecific marker for rhabdomyolysis. CK levels 5 times the reference range suggest rhabdomyolysis, although CK levels in rhabdomyolysis are frequently 100 times the reference range or even higher. ⚠ Choice B is not correct: Several studies have shown the benefits of ultrasound in the diagnosis of rhabdomyolysis. However, most consistent data is needed to rely on it as a diagnostic tool. ⚠ Choice C is not correct: Imaging studies in rhabdomyolysis may show signs of muscle edema and/or hemorrhage. Edematous muscles on CT scan are usually hypodense and possibly enlarged. ⚠ Choice D is not correct: Glycated hemoglobin, also known as HbA1c, can be used to check the blood sugar levels of prediabetics and monitor blood sugar control in patients with diabetes mellitus. Some studies have shown that elevated HbA1c levels predict acute kidney injury after coronary artery bypass grafting in non-diabetic patients. ⚠ Choice E is not correct: Aside from creatinine kinase, other muscle enzymes, such as aldolase, aminotransferases, lactate dehydrogenase, may be elevated in rhabdomyolysis. Their presence is not necessary to make the diagnosis. Summarized Points: The diagnostic hallmark of rhabdomyolysis is an elevation in serum creatinine kinase (CK) levels. These levels can range from about 1500 to over 100,000 international units/L and usually begin to rise within 2-12 hours following muscle injury and reach a peak within 24-72 hours. Another characteristic finding of rhabdomyolysis is reddish-brown urine from myoglobinuria, which may only be seen 50% of the time.

A 77-year-old woman was admitted from home because of syncope. Her daughter reports that the patient has been losing weight and rarely eating since the death of her husband about one year ago. In addition, the daughter states that her mother's urine has a dark colour to it and that she is very concerned. He laboratory results are the following:  Serum chemistry     Creatinine  247µmol/L (50-90)     Albumin 21 g/L (35-50)  Urinalysis     Blood positive   Urine microscopy shows 0-2 WBC and 0-2 RBC. The patient does not have a significant cardiac history, but she has diabetes and takes metformin 1000 mg twice a day. What is the next best step in determining the etiology of her acute kidney injury? A. Creatinine kinase level B. Renal ultrasound C. CT scan with IV contrast D. Glycated hemoglobin E. Lactate dehydrogenase level

The growing prevalence of overweight (body mass index [BMI] 85th–95th percentile) and obese (BMI ≥95th percentile) children has resulted in increasing rates of early dyslipidemia and metabolic syndrome. Children with a BMI ≥95th percentile should undergo fasting glucose testing to screen for diabetes mellitus, serum alanine aminotransferase (ALT) to screen for fatty liver disease, and a serum lipid panel to screen for dyslipidemia. Ideally, total cholesterol, triglycerides, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol are measured after the patient has fasted. Triglycerides in particular can remain elevated for several hours after a high-fat meal, but recent studies show that the other values may not be significantly affected by a recent meal. The first-line treatment for children with elevated LDL and triglycerides includes regular exercise, a healthy diet low in fat and cholesterol, avoiding sugary beverages, and minimizing television time to <2 hours per day. Addressing modifiable risk factors can delay, pause, or reverse the development of these complications. ⚠Choice B is not correct: Routine electrocardiogram in asymptomatic children with no significant family history of cardiac disease is low yield and not recommended. ⚠Choice C is not correct: If the serum ALT is elevated, a liver ultrasound can be performed to evaluate for fatty liver disease. ⚠Choice D is not correct: Testing should be performed to identify potentially treatable complications of obesity. ⚠Choice E is not correct: Hypothyroidism rarely causes obesity in isolation and usually manifests with other abnormalities (e.g., constipation, cold intolerance, fatigue). Summarized Points: Pediatric obesity is increasingly common and is associated with early complications such as dyslipidemia, fatty liver disease, and hypertension. Fasting glucose, serum alanine aminotransferase, and a lipid panel should be measured in these patients. Dietary and lifestyle modifications are the first-line treatment.

A 6-year-old girl is brought to the physician for a routine examination. She has no complaints and is enjoying first grade. Her favourite drink is orange juice, and she enjoys chips and cookies. The girl has no medical problems and takes no medications. The review of the systems is negative. Several maternal relatives are obese, but no family members have heart disease or stroke. There are no smokers in the home. Body mass index (BMI) was previously in the 80th percentile but is now in the 99th percentile. Vital signs are normal. Examination reveals central adiposity. No acanthosis nigricans is seen. Which of the following is the best next step in the management of this patient? A. Serum lipid panel B. 12-lead electrocardiogram C. Liver ultrasound D. No testing indicated at this age E. Serum thyroid function test

The correct answer is B. The patient in this question is presenting with acute cholecystitis. He is presenting with fever, right upper quadrant pain after a fatty meal that radiates to the right scapula, and positive Murphy sign (pain on palpation in the right upper quadrant with cessation of inspiration). Additional nonspecific findings include vomiting, leukocytosis, and mild elevation in transaminases. Acute cholecystitis usually arises from gallstone formation that obstructs the cystic duct. The symptoms occur after eating a fatty meal because the fat stimulates gallbladder contraction, and in the presence of cystic duct obstruction, this leads to colicky pain. Infection results from stasis that contributes to bacterial growth in the gallbladder. ⚠Choice A is not correct: Alcoholic liver disease does not present with this constellation of symptoms. ⚠Choice C is not correct: Similar to common bile duct obstruction, obstruction from a carcinoma of the head of the pancreas would cause severely elevated alkaline phosphatase levels and would normally present with weight loss and painless jaundice. ⚠Choice D is not correct: Importantly, alkaline phosphatase is not elevated in this patient with acute cholecystitis. Assume if laboratories are not shown, they are normal. If it were elevated (in addition to total bilirubin and direct bilirubin), this might indicate common bile duct obstruction in the setting of jaundice (choledocolithiasis). ⚠Choice E is not correct: Pancreatitis should definitely be ruled out with a lipase check, but pain typically is only epigastric in nature and radiates to the back. Summarized Points: acute cholecystitis presents with fever, right upper quadrant pain after a fatty meal that radiates to the right scapula, and positive Murphy sign (pain on palpation in the right upper quadrant with cessation of inspiration). Usually caused by gallstone formation that obstructs the cystic duct.

A 49-year-old female presents to the emergency department with complaint of severe epigastric and right upper quadrant (RUQ) abdominal pain. Her symptoms started 3 days ago but have progressively worsened over the past 12 hours. Her symptoms are worse with meals. She has had two episodes of vomiting in the past 12 hours and is nauseous currently. Past medical history is significant for diabetes, osteoarthritis, and hypertension. Her blood pressure is 146/80 mmHg, pulse is 110/min, respiratory rate is 16/min, temperature is 39 C (102.3 F). On physical examination, there is severe right upper quadrant pain on deep palpation, most pronounced on palpation after deep inspiration. Bowel sounds are diminished. The patient is lying on her side holding an emesis basin. Which of the following is causing this patient’s disorder? A. Alcoholic liver disease B. Gallstone obstruction in the cystic duct C. Obstruction from carcinoma of the head of the pancreas D. Gallstone obstruction in the common bile duct E. Pancreatic inflammation

This patient with known asthma has recurrent exacerbations with fever and expectoration of dark brown mucus, which is suggestive of allergic bronchopulmonary aspergillosis (ABPA). Patients may experience additional systemic symptoms (e.g., anorexia, malaise, or weight loss) or have hemoptysis. ABPA is caused by hypersensitivity to bronchial colonization by Aspergillus fumigatus. It occurs more commonly in asthmatics and patients with cystic fibrosis. Proteolytic enzymes and mycotoxins induce an intense inflammatory reaction that can eventually cause bronchiectasis and fibrosis. Early diagnosis is important as the onset of bronchiectasis is associated with poor outcomes. Diagnosis is based on clinical and radiographic features and immunologic testing. Immediate cutaneous hypersensitivity to skin prick testing is a characteristic finding. If negative, intradermal reactivity may be tested for confirmation. A negative skin prick test and intradermal reactivity excludes the diagnosis. If positive, immunologic testing is performed. High-resolution CT characteristically shows infiltrates, central bronchiectasis, and mucus-filled bronchi (mucoid impaction). A positive bronchodilator response on pulmonary function tests is only seen in about 50% of patients. Treatment involves a combination of corticosteroids and antifungal agents (e.g., itraconazole). ⚠ Choice A is not correct: Bronchoalveolar lavage specimens may show Aspergillus species. However, the test is more invasive and is usually not indicated. ⚠ Choice B is not correct: Common variable immunodeficiency (CVID) can present with recurrent pulmonary infections and bronchiectasis, but it does not cause recurrent asthma exacerbations responsive to steroids. ⚠ Choice C is not correct: Induced sputum for Pneumocystis jirovecii may be helpful to diagnose Pneumocystis pneumonia in an asthmatic taking high-dose chronic oral steroids. However, this patient was only on intermittent steroids. ⚠ Choice D is not correct: Patients with tuberculosis may also present with chronic cough and constitutional symptoms, but these are progressive (not intermittent) and do not respond to steroids. Summarized Points: Allergic bronchopulmonary aspergillosis is a hypersensitivity reaction to Aspergillus that may colonize the airways of patients with asthma and cystic fibrosis. It presents with worsening asthma symptoms, fever, fleeting infiltrates, pleuritic chest pain, and peripheral eosinophilia. The first step in diagnosis is Aspergillus skin testing. If left untreated, the disorder can result in bronchiectasis with a poor prognosis.

A 36-year-old life-long asthmatic has repeated episodes of asthma exacerbation accompanied by fever and thick brownish sputum that respond to oral prednisone therapy. His leukocyte count is 8,500/µL with 15% eosinophils. Chest x-ray reveals bronchiectasis on the left side. Which of the following is the best next step in the management of this patient? A. Bronchoscopy with bronchoalveolar lavage B. Immunoglobulin levels to evaluate for immunodeficiency C. Induced sputum for Pneumocystis jirovecii D. Purified protein derivative test E. Aspergillus skin testing

- MCCQE Part I Full-length Preparatory Examination (PE) Qbank (April 2023) (PDF) 🇨🇦 https://mcc.ca/examinations/mccqe-part-i/preparation-resources/preparatory-products/ Contents included: - 210 Multiple-Choice Questions (MCQs) - 38 Clinical Decision-Making cases (CDMs) - Full answer key including rationales and references 📲➕ Contact Admin: @Mediccounts

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The correct answer is A. Supraventricular tachycardias (SVT) include paroxysmal, reentry, or preexcitation tachycardias. Reentry SVTs include AV nodal reentry (AVNRT), atrioventricular reentry, or atrial reentry. Reentry circuits require the presence of at least two different conduction pathways with differential refractory times. It is characterized by an abrupt onset and termination of tachycardia, that distinguishes it from sinus tachycardia, which has gradual changes in rate. It is precipitated by a premature atrial or ventricular contraction or hyperadrenergic state. Other triggers include hyperthyroidism and stimulants, including caffeine, drugs, and alcohol. This patient has supraventricular tachycardia (SVT) likely related to atrioventricular nodal reentrant tachycardia (AVNRT) and he has no concerning symptoms. The ECG shows a regular, fast rhythm with absent P waves and a narrow QRS complex. Unstable patients require immediate synchronized cardioversion. Stable patients, such as the patient above, should first undergo vagal maneuvers. Some common vagal maneuvers include holding your breath and bearing down (Valsalva maneuver), coughing, gagging, and immersing your face in ice-cold water. If vagal maneuvers are unsuccessful, adenosine is used both diagnostically and therapeutically. Adenosine transiently blocks the AV-node and allows the circuit to “reset.” ⚠Choice B is not correct: Adenosine is very short acting and can be used if vagal maneuvers fail to terminate the arrhythmia. ⚠Choice C is not correct: Metoprolol would also be considered if the above measures failed. ⚠Choice D is not correct: Digoxin would also inhibit the AV node but has more potential side effects than the other medications and is rarely used for this purpose. ⚠Choice E is not correct: Cardioversion would be reserved for hemodynamic instability including hypotension, heart failure, or angina. Summarized Points: This patient has SVT likely related to AVNRT and he has no concerning symptoms. The initial attempts at termination should use vagal maneuvers such as the Valsalva maneuver.

A 40-year-old man is evaluated for palpitations in the emergency department. He has had these symptoms several times over the past year but this episode is worse. He denies any associated chest pain, lightheadedness, or syncope. He denies any history of medical problems and takes no medications. Examination reveals an adult male in no significant distress. Cardiac examination is significant for regular tachycardia with no jugular venous pressure elevation. Lungs are clear without crackles or wheezing. There is no lower extremity edema. ECG shown below. What is the best intervention at this point? A. Valsalva maneuver B. Adenosine C. Metoprolol D. Digoxin E. Cardioversion