Tüm alıştırma soruları

An oncologist evaluates a $52$-year-old woman during a routine follow-up visit. The patient has HER2-amplified, estrogen receptor-negative early-stage breast cancer. Three months ago, she completed adjuvant therapy with doxorubicin and cyclophosphamide and was subsequently started on maintenance therapy with trastuzumab.

The patient reports feeling well with no shortness of breath, orthopnea, or lower extremity edema. She walks $3$ kilometers daily without difficulty. Vital signs are within normal limits. Physical examination reveals clear lungs bilaterally, no jugular venous distention, and no peripheral edema.

A summary of her echocardiogram reports is provided below:

Which of the following is the most appropriate next step in managing this patient's therapy?

An epidemiology research group is utilizing data and stored biological specimens from a large, ongoing prospective cohort study of $80,000$ healthy adults that began $15$ years ago. The researchers want to investigate whether elevated baseline serum levels of a newly identified inflammatory cytokine, Cytokine-X, are associated with an increased risk of developing multiple sclerosis (MS). During the $15$-year follow-up period, $120$ participants developed MS. Measuring Cytokine-X is technically demanding and highly expensive; therefore, it is financially impossible to assay the stored baseline serum samples of all $80,000$ participants. The investigators plan to measure the cytokine levels in the baseline serum of the $120$ participants who developed MS and compare them to the baseline serum of a randomly selected subgroup of participants who remained free of the disease, matched for age and sex. Which of the following best describes this study design?

A clinical research organization is finalizing the methodology for a randomized, placebo-controlled trial evaluating a novel pharmacologic agent for generalized anxiety disorder. The investigators stipulate that they are willing to accept a 5% risk of concluding the agent is effective when it is truly no different from placebo. Furthermore, formal sample size calculations reveal a 0.14 probability of concluding that the drug has no effect when it actually provides a clinically meaningful benefit to patients.

Based on these parameters, what is the planned statistical power of this trial, expressed as a percentage?

A 45-year-old woman returns to the outpatient clinic to review the results of a recent breast biopsy. The pathology report confirms a diagnosis of invasive ductal carcinoma. The physician prepares to deliver this bad news to the patient. Arrange the following physician statements in the most appropriate chronological order according to the established framework for delivering bad news (the SPIKES protocol).

A $64$-year-old man presents to the clinic for a follow-up visit. Over the past four weeks, he has experienced progressive fatigue, an unintentional weight loss of $4$ kg ($8.8$ lb), and intermittent palpitations. He has a history of ischemic cardiomyopathy with a left ventricular ejection fraction of $30\%$ and recurrent sustained ventricular tachycardia. His medications include lisinopril, carvedilol, spironolactone, and amiodarone. He has been taking amiodarone for the past $2$ years. Vital signs show a blood pressure of $118/76$ mmHg and an irregularly irregular pulse of $112$/min. Physical examination is notable for a fine resting tremor and warm, diaphoretic skin. The thyroid gland is not enlarged, and there is no tenderness to palpation.

Laboratory studies reveal the following:

A color flow Doppler ultrasonography of the thyroid gland demonstrates a normal-sized gland with markedly decreased vascular flow.

Which of the following is the most appropriate next step in the pharmacologic management of this patient's thyroid dysfunction?

Investigators are planning a randomized, double-blind, placebo-controlled trial to evaluate the efficacy of a novel neuroprotective medication for acute ischemic stroke. The primary outcome is the total volume of cerebral infarction at 90 days. During the design phase, the steering committee modifies the study protocol. Instead of estimating infarct volume using standard non-contrast computed tomography (CT), which has substantial inter-reader variability, the study will now utilize high-resolution magnetic resonance imaging (MRI) with an automated volumetric analysis algorithm. This change significantly improves measurement precision and reduces outcome variance. The anticipated true difference in mean infarct volume between the groups (effect size), the total number of enrolled patients, and the predefined significance level ($\alpha = 0.05$) remain unchanged. Which of the following best describes the expected statistical impact of this protocol modification?

A team of pediatric cardiologists is investigating a potential link between maternal use of a newly approved antiemetic during the first trimester and the development of a rare congenital ventricular septal defect (estimated prevalence of $1$ in $15,000$ live births). To conduct the study efficiently, the investigators use a national birth defect registry to identify $250$ infants diagnosed with this specific anomaly. They also select $1,000$ healthy infants from the same registry, matched to the affected infants by birth year, maternal age category, and geographic region. The researchers then conduct structured telephone interviews with all the mothers to ascertain their history of antiemetic use and other medication exposures during early pregnancy. Which of the following statements regarding this study's methodological design and analysis are correct? (Select all that apply)

A physician-scientist at a tertiary care clinic is designing a prospective trial to compare the efficacy of two different basal insulin regimens in patients with poorly controlled type 2 diabetes. The initial statistical analysis plan defines the primary endpoint as the absolute reduction in hemoglobin A1c (HbA1c), measured as a continuous variable. A preliminary sample size calculation indicates that $400$ patients are required to detect a clinically significant mean difference of $0.5\%$ between the groups with $80\%$ power and a two-sided $\alpha$ of $0.05$.

During a peer-review meeting, a colleague suggests altering the primary endpoint to a dichotomous outcome: the proportion of patients who successfully achieve an HbA1c of $< 7.0\%$ by the end of the observation period.

If this modification is adopted and the total sample size remains fixed at $400$ patients, which of the following is the most likely statistical consequence?

During a grand rounds presentation, a cardiologist discusses the findings of the recent VANGUARD trial, which evaluated the addition of a novel aldosterone synthase inhibitor to standard therapy in patients with resistant hypertension. The primary goal of the study was to assess the reduction in major adverse cardiovascular events (MACE) over 4 years.

The trial included 5,000 participants evenly divided into an intervention arm and a standard-care arm. The following event data were recorded during the follow-up period:

A resident is asked to interpret the clinical impact of these findings for a patient considering the new therapy. Based on the provided data, what are the number needed to treat (NNT) to prevent one MACE and the number needed to harm (NNH) for severe hyperkalemia, respectively?

A team of hepatologists is evaluating the impact of three distinct dietary regimens—Mediterranean, low-fat, and ketogenic—on liver fibrosis progression in patients with metabolic dysfunction-associated steatotic liver disease (MASLD). A total of 150 patients are randomly assigned in equal proportions to one of the three diets for a period of 6 months. The primary outcome is the change in liver stiffness, measured continuously in kilopascals (kPa) using transient elastography, from baseline to the end of the study period. A preliminary analysis of the data reveals that the changes in liver stiffness measurements across all three groups are highly right-skewed and do not follow a normal distribution. Which of the following statistical tests is most appropriate to determine if there is a significant difference in the change in liver stiffness among the three dietary groups?

During an outpatient endocrine evaluation, a physician evaluates a patient suffering from new-onset, treatment-resistant hypertension, marked proximal myopathy, and progressive truncal adiposity. The patient exhibits classic cutaneous findings, including facial plethora and broad, violaceous abdominal striae. Recent laboratory work definitively established a diagnosis of endogenous hypercortisolism via two distinct, abnormal screening tests: a markedly elevated late-night salivary cortisol and an unsuppressed morning cortisol following a 1-mg overnight dexamethasone suppression test. To elucidate the underlying etiology of this patient's hypercortisolism, which of the following investigations is the most appropriate next step in the diagnostic sequence?

A 71-year-old male resident of a skilled nursing facility is transferred to the acute care hospital due to a 3-day history of progressive confusion and reduced oral intake. His past medical history includes type 2 diabetes mellitus, hypertension, and osteoarthritis. Current medications include amlodipine, metformin, and acetaminophen.

On arrival, his temperature is 36.8°C (98.2°F), pulse is 102/min, blood pressure is 105/60 mm Hg, and respiratory rate is 16/min. The patient is somnolent but arousable and oriented to person only. Physical examination is notable for dry mucous membranes and decreased skin turgor. Cardiopulmonary and abdominal examinations are unremarkable.

Laboratory evaluation reveals:
Serum sodium: 118 mEq/L
Serum potassium: 4.0 mEq/L
Serum chloride: 85 mEq/L
Serum bicarbonate: 25 mEq/L
Blood urea nitrogen (BUN): 38 mg/dL
Serum creatinine: 1.5 mg/dL (baseline: 1.0 mg/dL)
Serum glucose: 140 mg/dL
Serum osmolality: 250 mOsm/kg $H_2O$

Urine studies:
Urine sodium: 12 mEq/L
Urine osmolality: 450 mOsm/kg $H_2O$

The admitting physician initially suspects the syndrome of inappropriate antidiuretic hormone (SIADH) as the primary etiology for the severe hyponatremia. However, upon reviewing the comprehensive clinical and laboratory data, the physician realizes this differential diagnosis is incorrect.

Based on the provided data, which of the following is the most accurate primary differential diagnosis for this patient's hyponatremia?

A female patient, aged 64, is evaluated in the ambulatory clinic for ongoing exertional dyspnea. She was diagnosed with heart failure with reduced ejection fraction two years ago following an anterior myocardial infarction. Current symptoms include shortness of breath when walking up a single flight of stairs, consistent with New York Heart Association class II symptoms. Her medical history includes type 2 diabetes mellitus and hypertension.

Current medications are lisinopril, metoprolol succinate, empagliflozin, and torsemide as needed.

Vital signs show a blood pressure of $118/76$ mm Hg and a heart rate of $68$/min. Physical examination reveals a normal jugular venous pressure, clear lungs, and trace bilateral pedal edema.

Recent laboratory studies:
Sodium: $138$ mEq/L
Potassium: $4.5$ mEq/L
Creatinine: $1.1$ mg/dL (baseline $1.0$ mg/dL)

An echocardiogram from one month ago shows a left ventricular ejection fraction of $32\%$.

The physician plans to transition the patient from her current angiotensin-converting enzyme inhibitor to sacubitril-valsartan to further reduce the risk of cardiovascular mortality and heart failure hospitalization.

Which of the following is the most appropriate step in implementing this pharmacologic intervention?

A $58$-year-old man with a history of alcohol-associated cirrhosis is admitted to the intensive care unit with fever, hypotension, and a productive cough. He is diagnosed with severe community-acquired pneumonia and started on broad-spectrum intravenous antibiotics and fluid resuscitation. On the second day of admission, the nurse notes continuous oozing of blood from his peripheral intravenous catheter sites.

Laboratory studies reveal the following:

The attending physician suspects disseminated intravascular coagulation (DIC) secondary to sepsis, but must differentiate this from the patient's baseline coagulopathy of liver disease. Which of the following laboratory findings would most specifically confirm a diagnosis of disseminated intravascular coagulation (DIC) rather than isolated coagulopathy of liver disease in this patient?

A 42-year-old man presents to the clinic for a routine evaluation. He reports a 2-year history of excessive sweating, fatigue, and loud snoring that frequently wakes his spouse. He mentions that his wedding ring no longer fits and his shoe size has increased from size 10 to 12 over the past few years. He has a history of hypertension and takes amlodipine. Vital signs show a blood pressure of 152/94 mm Hg, pulse of 78/min, and BMI of 31 kg/m². Physical examination reveals coarse facial features, a prominent jaw, and a widened space between his lower incisors. His hands are enlarged and doughy. There is no visual field deficit on confrontation testing. Which of the following is the most appropriate next step in the diagnostic workup of this patient's condition?

While awaiting a routine appointment in the outpatient pulmonary clinic, a $62$-year-old man suddenly begins coughing up large volumes of bright red blood. Within minutes, he expectorates more than $400\text{ mL}$ of blood into a basin. The patient becomes highly agitated, profoundly diaphoretic, and visibly struggles to breathe. His medical history is significant for pulmonary tuberculosis that was treated $15$ years ago. Clinic staff immediately transfer him to the adjacent emergency department resuscitation bay. Vital signs show a heart rate of $128/\text{min}$, blood pressure of $115/75\text{ mmHg}$, and a respiratory rate of $34/\text{min}$. Pulse oximetry reveals an oxygen saturation of $83\%$ on room air. Chest auscultation demonstrates coarse gurgling and diminished breath sounds predominantly over the right lung fields.

Which of the following is the most appropriate immediate next step in the management of this patient?

An elderly man is admitted due to a two-week history of worsening dyspnea, orthopnea, and increasing lower extremity edema. His past medical history is significant for ischemic cardiomyopathy with a left ventricular ejection fraction of $30\%$. To manage his fluid overload at home, he recently doubled his daily dose of oral torsemide independently.

Upon admission, his blood pressure is $92/58\text{ mmHg}$, pulse is $108/\text{min}$, and respiratory rate is $22/\text{min}$. Jugular venous pressure is visibly elevated. Lung auscultation reveals bilateral basilar crackles, and a third heart sound (S3) is present on cardiac exam.

Laboratory evaluation yields the following results:
Serum chemistry:
Sodium: $132\text{ mEq/L}$
Potassium: $3.1\text{ mEq/L}$
Chloride: $94\text{ mEq/L}$
Bicarbonate: $29\text{ mEq/L}$
Blood urea nitrogen (BUN): $75\text{ mg/dL}$
Creatinine: $2.5\text{ mg/dL}$ (baseline $1.2\text{ mg/dL}$)

Spot urine chemistry:
Sodium: $66\text{ mEq/L}$
Urea nitrogen: $450\text{ mg/dL}$
Creatinine: $60\text{ mg/dL}$

To evaluate the etiology of the acute kidney injury in the setting of recent loop diuretic use, the medical team decides to calculate a specific fractional excretion index that is less confounded by his medication regimen than sodium excretion.

What is the calculated value of this preferred index, expressed as a percentage?

A 45-year-old male is evaluated in the infectious disease clinic for a 6-week history of low-grade fevers, drenching night sweats, a productive cough, and a 6.8-kg (15-lb) weight loss. His medical history is significant for severe, seropositive rheumatoid arthritis that has been well-controlled for the past two years. His current medications include methotrexate, infliximab, and as-needed ibuprofen. Social history reveals that he works as a landscaping contractor in Ohio. He returned from a one-week resort vacation in the Dominican Republic two months ago. He has a 10 pack-year history of cigarette smoking but quit 5 years ago. Vital signs show a temperature of 38.2°C (100.8°F), blood pressure of 122/78 mmHg, heart rate of 94/min, and respiratory rate of 18/min. Physical examination reveals bronchial breath sounds and post-tussive crackles in the right upper lung field. A chest radiograph demonstrates a 3.5-cm cavitary lesion in the right upper lobe without significant hilar adenopathy. When evaluating this patient's comprehensive history to establish the primary etiology of his current condition, which of the following elements is the most critical risk factor?

A $48$-year-old woman is brought to the emergency department due to a $3$-day history of progressively worsening, severe headache, accompanied by nausea and blurred vision. She has a past medical history of systemic lupus erythematosus and currently takes oral contraceptives. Her blood pressure is $142/88$ mmHg, pulse is $88$/min, and temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$). Physical examination reveals bilateral papilledema. Neurologic examination is notable for $4/5$ strength in the left upper and lower extremities. A non-contrast computed tomography (CT) scan of the head is obtained. The images reveal a prominent hyperdense signal within the posterior aspect of the superior sagittal sinus. Additionally, there is a $1.5$-cm area of hyperdensity in the right frontal parasagittal parenchyma surrounded by a distinct halo of hypodensity. Based on the interpretation of these imaging findings, which of the following is the most appropriate next step in management?

Match each laboratory profile of thyroid function to its most likely clinical diagnosis. Reference ranges are as follows: TSH $0.4$-$4.0$ $\mu$ U/mL; Free T4 $0.9$-$1.7$ ng/dL; 24-hr Radioactive Iodine Uptake (RAIU) $10\%$-$30\%$; Thyroglobulin $3$-$40$ ng/mL.