Medical Council of Canada MCCQE - MCCQE Part 1 Exam

Comprehensive and Detailed Explanation:

The combination of upper extremity hypertension and weak femoral pulses is classic for aortic coarctation. A soft systolic murmur may be present. This condition often becomes apparent during routine screening in school-aged children.

Toronto Notes 2023 – Pediatrics / Cardiology:

“Coarctation of the aorta presents with upper limb hypertension, diminished femoral pulses, and sometimes a systolic murmur. BP discrepancy is key.”

MCCQE1 Objectives (Pediatrics > 78-1: Congenital Heart Disease):

“Candidates must recognize signs of aortic coarctation, including weak lower limb pulses and systemic hypertension in children.”

VSD (A) typically presents with a louder murmur. Reflux nephropathy (B) may cause hypertension but without femoral pulse discrepancy. Renal artery thrombosis (C) is rare. Essential hypertension (D) is less likely in this age group with these findings.

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In a patient with known diverticular bleeding and no red flags (e.g., weight loss, anemia, family history), repeating colonoscopy is not required. Diverticular bleeding is typically self-limited. Colonoscopy within the past few years with clear findings suffices.

Toronto Notes 2023 – Gastroenterology, Lower GI Bleed:

“Patients with known diverticulosis and self-limited bleeding who have had prior complete colonoscopy do not require repeat endoscopy unless symptoms recur or persist.”

MCCQE1 Objectives – Internal Medicine > Gastroenterology:

“Candidates must recognize when no further invasive investigation is necessary in elderly patients with known benign findings and resolved symptoms.”

Option E is considerate but not clinically necessary for independent patients. Options A, B, and D are not indicated in resolved, low-risk cases.

Comprehensive and Detailed Explanation:

The image and clinical history are consistent with physiologic pubertal gynecomastia, which is common in adolescent boys. It usually resolves spontaneously within 6 months to 2 years and does not require investigation unless other signs of endocrine pathology are present.

Toronto Notes 2023 – Pediatrics / Endocrinology:

“Pubertal gynecomastia is benign, self-limited, and common in adolescent males. No further investigation is needed in the absence of systemic signs.”

MCCQE1 Objectives (Pediatrics > 77-2: Endocrine Disorders):

“Candidates must differentiate physiologic gynecomastia from pathologic causes based on history and physical exam.”

Other tests (A–C, E) are unnecessary unless there are red flags (e.g., testicular mass, rapid progression, neurological symptoms).

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A confounder is a variable associated with both the exposure and the outcome but not in the causal pathway. In this study, coffee drinking is associated with smoking (the actual risk factor for lung cancer), but not independently associated with lung cancer.

Toronto Notes 2023 – Epidemiology Chapter:

“A confounder is a third variable that distorts the observed association between an exposure and an outcome. It must be associated with both the exposure and the outcome, but not a result of the exposure.”

MCCQE1 Objectives (Population Health > 97-3: Study Design and Bias):

“Recognize and control for confounding in the interpretation of observational study data.”

Coffee is not a risk factor (B) since it’s not independently associated with lung cancer, and it's not selection bias (C), which involves how participants are enrolled in a study.

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The patient is alert and capable of making his own decisions. The most ethical and respectful approach is to ensure he understands the risks and accept his choice. Holding his bed maintains continuity of care. Forcing him to stay (C) or discharging him AMA (A) is inappropriate if he intends to return.

Toronto Notes 2023 – ELOM, Consent and Autonomy:

“Capable patients have the right to refuse or leave treatment. Physicians must ensure informed decision-making and maintain therapeutic rapport.”

MCCQE1 Objectives – ELOM > Capacity and Patient Autonomy:

“Candidates must respect a capable patient’s right to leave care after informed discussion of risks and alternatives.”

Offering to enter his apartment (E) is inappropriate and unethical. Oral antibiotics (B) may not be clinically appropriate given hypotension.

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Comprehensive and Detailed Explanation:

The levonorgestrel-releasing intrauterine device (LNG-IUD) is generally contraindicated in current or recent breast cancer due to the progestin component, but may be considered in selectpatients on tamoxifen, especially if non-hormonal options are unsuitable. Consultation with the oncologist is required to evaluate risks and benefits.

Toronto Notes 2023 – Gynecology, “Contraception in Special Populations”:

“Levonorgestrel IUDs are generally avoided in patients with a history of hormone-sensitive cancers; however, decisions should be made collaboratively with oncology.”

MCCQE1 Objectives (Gynecology > 82-2: Contraception):

“Candidates must tailor contraceptive advice to patients with medical comorbidities, including cancer survivors.”

Irregular bleeding (A) is a common but not contraindicating side effect. No pre-procedure antibiotics (D) are typically needed. The IUD does not cause infertility (E). Risk of recurrence (C) is unconfirmed and must be individualized.

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Comprehensive and Detailed Explanation:

This patient has hypercalcemia with suppressed PTH, ruling out primary hyperparathyroidism. The differential includes malignancy-associated hypercalcemia, vitamin D intoxication, and medications. Given the low PTH and normal vitamin D level, malignancy (e.g., multiple myeloma) is a leading concern. Serum protein electrophoresis and urine for Bence-Jones proteins (light chains) are appropriate next steps.

Toronto Notes 2023 – Endocrinology, “Hypercalcemia”:

“PTH-independent hypercalcemia should prompt investigation for malignancy. Multiple myeloma is a common cause in older adults—order SPEP and UPEP.”

MCCQE1 Objectives (Endocrinology > 37-1: Calcium Disorders):

“Candidates must investigate non-PTH mediated hypercalcemia, including consideration of multiple myeloma.”

A (urine calcium) helps in familial hypocalciuric hypercalcemia, but this is unlikely given low PTH. B (calcitriol) would worsen hypercalcemia. C is inappropriate because PTH is suppressed. D (changing HCTZ) may help, but malignancy must be ruled out first.

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Comprehensive and Detailed Explanation:

Decreased libido in elderly patients can be multifactorial, but depression is a common and important cause that must be ruled out before hormone therapy or other steps. A proper mental health screen should precede further interventions.

Toronto Notes 2023 – Psychiatry / Geriatrics:

“In elderly men, reduced libido may be linked to depression, medical illness, or medications. Depression screening is essential.”

MCCQE1 Objectives (Psychiatry > 71-1: Mood Disorders / Sexual Health):

“Candidates must consider depression as a common cause of decreased libido and assess accordingly before initiating hormone therapy.”

Testosterone testing (D) may follow. Prescribing (C) is premature. Couples counselling (B) may help if interpersonal issues are identified. Interviewing together (A) may inhibit disclosure.

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Calculating food-specific attack rates (i.e., number of people who became ill after eating aparticular food divided by the total number who ate that food) is the most effective method to identify the probable source of infection in a known cohort outbreak.

Toronto Notes 2023 – Public Health, Outbreak Investigations:

“Foodborne outbreaks are best analyzed using food-specific attack rates to determine associations between individual foods and illness.”

MCCQE1 Objectives – Preventive Medicine > Epidemiologic Principles:

“Candidates must use epidemiologic tools, such as attack rates, to identify probable sources during outbreak investigations.”

Cohort study (C) is also acceptable but more time-intensive. Stool and food cultures (B, D) confirm the pathogen but not the source. HACCP (E) is a preventive method, not a tool for outbreak investigation.

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