All practice questions

A 64-year-old man is evaluated in the intensive care unit for a progressive decline in urine output. Three days ago, he underwent an emergent exploratory laparotomy for a perforated duodenal ulcer. His postoperative course was complicated by hypotension requiring vasopressor support for 24 hours, but he is currently hemodynamically stable. His urine output over the last 8 hours has been 120 mL.

Laboratory studies are obtained and reveal the following:

Serum chemistry
Sodium: $140$ mEq/L
Potassium: $4.8$ mEq/L
Chloride: $105$ mEq/L
Bicarbonate: $20$ mEq/L
BUN: $42$ mg/dL
Creatinine: $2.0$ mg/dL (baseline was $0.9$ mg/dL)

Urine studies
Sodium: $70$ mEq/L
Creatinine: $50$ mg/dL
Osmolality: $310$ mOsm/kg $H_2O$

Based on these laboratory results, what is the patient's fractional excretion of sodium (FENa)? Give your answer as a percentage.

A 28-year-old woman is evaluated in the outpatient clinic for a 6-month history of amenorrhea and bilateral nipple discharge. She also reports increasing fatigue, constipation, and an $8\text{-kg}$ ($17.6\text{-lb}$) weight gain over this period. Her only medication is a daily multivitamin. Vital signs are temperature $36.2^\circ\text{C}$ ($97.2^\circ\text{F}$), blood pressure $112/74\text{ mm Hg}$, pulse $54\text{/min}$, and respiratory rate $12\text{/min}$. Physical examination reveals a delayed relaxation phase of the deep tendon reflexes. A milky discharge can be easily expressed from both breasts.

Laboratory studies show the following:

Based on the provided laboratory results, which of the following mechanisms is most likely responsible for this patient's elevated prolactin level?

A $38$-year-old woman is evaluated in the clinic for episodes of severe palpitations, pounding headaches, and profuse sweating. These episodes occur unexpectedly, last for $15$ to $20$ minutes, and resolve spontaneously. She has had four such episodes over the past month. During a recent episode, she was evaluated at an urgent care center where her blood pressure was $185/110\text{ mmHg}$ and her heart rate was $115\text{/min}$. Today, she feels well. Her blood pressure is $122/78\text{ mmHg}$ and heart rate is $72\text{/min}$. The physical examination is unremarkable. Which of the following is the most appropriate next step in laboratory evaluation?

A 52-year-old woman is brought to the emergency department by her husband due to altered mental status and confusion. She has a history of type 2 diabetes mellitus and severe chronic osteoarthritis of the knees, for which she takes multiple over-the-counter analgesics. For the past three days, the patient has experienced severe nausea, tinnitus, and intractable nonbilious vomiting.

Vital signs show a temperature of 38.2°C (100.8°F), pulse of 118/min, blood pressure of 105/65 mm Hg, and respiratory rate of 26/min. Physical examination reveals dry mucous membranes, diffuse mild abdominal tenderness, and tachypnea with clear lungs bilaterally.

Laboratory results are as follows:

Arterial blood gas (room air):

Based on the provided laboratory data, which of the following best characterizes this patient's acid-base status?

A 52-year-old man presents to the clinic for a follow-up evaluation of seropositive rheumatoid arthritis. Over the past 8 months, he has been treated with optimized doses of methotrexate, but he continues to experience significant morning stiffness and synovitis in his metacarpophalangeal and proximal interphalangeal joints. The physician decides to initiate targeted therapy with infliximab. Prior to starting the medication, an interferon-gamma release assay (IGRA) is performed and returns positive. A subsequent chest radiograph is clear, and the patient reports no cough, fever, or weight loss. Which of the following immunologic processes is most directly impaired by the planned biologic therapy, prompting the need for this screening?

A 26-year-old man presents to the urgent care clinic with a 1-week history of profound fatigue, nausea, anorexia, and right upper quadrant abdominal pain. He recently noticed that his eyes appear yellowish and his urine has become dark. His medical history is unremarkable, and he takes no prescription medications, over-the-counter drugs, or herbal supplements. He does not consume alcohol. He reports having unprotected sexual intercourse with a new partner approximately three months ago. Vital signs are within normal limits. Physical examination reveals scleral icterus and a tender liver edge palpable 3 cm below the right costal margin.

Laboratory studies are obtained:

Based on the provided clinical presentation and laboratory results, which of the following is the most likely diagnosis?

A 27-year-old primigravida at 23 weeks of gestation is evaluated in the emergency department for right-sided abdominal pain that started yesterday. The pain was initially dull and located around the umbilicus but has progressively worsened and shifted to the right mid-abdomen over the last twelve hours. She reports severe nausea and has vomited twice. Her temperature is 38.0°C (100.4°F), blood pressure is 112/74 mmHg, and heart rate is 102/min. On physical examination, there is marked tenderness to palpation in the right mid-abdomen, superior to the typical location of McBurney's point. Rebound tenderness is absent. Fetal heart tones are normal. Laboratory analysis shows a leukocyte count of 14,500/mm³ with 82% neutrophils. A graded compression transabdominal ultrasound is performed by an experienced sonographer, but the appendix cannot be visualized due to displacement by the enlarged uterus and acoustic shadowing from overlying bowel gas. Which of the following is the most appropriate next diagnostic step?

Match each physical examination maneuver with the specific musculoskeletal or neurological pathology it is most commonly used to diagnose.

A 34-year-old woman is admitted to the intensive care unit with severe sepsis secondary to acute pyelonephritis. On her second day of admission, the nursing staff notes persistent bleeding from her intravenous catheter sites and new-onset ecchymoses over her extremities. Her temperature is 38.8°C (101.8°F), blood pressure is 90/60 mmHg, and pulse is 115/min. Laboratory studies are obtained and show the following:

Which of the following is the most likely diagnosis based on these laboratory findings?

During a routine preoperative evaluation for an elective total knee arthroplasty, an asymptomatic 79-year-old woman is noted to have a prominent cardiac murmur. She denies any recent syncope, angina, or dyspnea, although she admits her activity level is minimal due to severe osteoarthritis. Vital signs show a blood pressure of 124/76 mmHg and a regular pulse of 68/min. Cardiac auscultation at the right second intercostal space reveals a loud crescendo-decrescendo systolic ejection murmur that radiates to the carotid arteries. The anesthesiologist requests a cardiology consultation to determine if the valvular lesion is hemodynamically significant, which would increase her perioperative risk.

Which TWO of the following concurrent physical examination findings would most strongly indicate that this patient's aortic stenosis is hemodynamically severe? (Select exactly two options)

A 68-year-old woman with a history of stage 4 chronic kidney disease presents to the clinic for a routine follow-up. Laboratory evaluation reveals a serum calcium level of 7.8 mg/dL and an elevated intact parathyroid hormone level. The physician notes that her hypocalcemia is primarily driven by the loss of functional renal parenchyma, which impairs a critical step in a major endocrine pathway. To review the pathophysiology of her condition, arrange the following biochemical and cellular events involved in the synthesis and mechanism of action of the deficient hormone in the correct chronological sequence, beginning with the initial precursor event.

A 27-year-old woman with a history of type 1 diabetes mellitus presents to the emergency department with abdominal pain, nausea, and severe, intractable vomiting for the past 48 hours. She stopped taking her insulin yesterday due to an inability to tolerate oral intake. On physical examination, her pulse is 118/min, blood pressure is 98/60 mm Hg, and respiratory rate is 18/min. Her mucous membranes are dry.

Arterial blood gas on room air reveals:
pH: $7.38$
$pCO_2$: $42 \text{ mm Hg}$

Serum laboratory results are as follows:
Sodium: $140 \text{ mEq/L}$
Potassium: $3.1 \text{ mEq/L}$
Chloride: $88 \text{ mEq/L}$
Bicarbonate: $24 \text{ mEq/L}$
Glucose: $610 \text{ mg/dL}$
Blood urea nitrogen: $42 \text{ mg/dL}$
Creatinine: $1.8 \text{ mg/dL}$

To evaluate for the presence of a mixed acid-base disorder, the physician calculates the delta-adjusted bicarbonate (also known as the expected bicarbonate derived from the delta gap). Assuming a baseline normal anion gap of $12 \text{ mEq/L}$, what is this patient's delta-adjusted bicarbonate (in mEq/L)?

A 54-year-old man visits an urgent care clinic reporting four days of a progressively worsening cough, subjective fevers, and sharp pain on the right side of his chest that intensifies during inspiration. His temperature is $38.9^\circ\text{C}$ ($102^\circ\text{F}$), blood pressure is $118/76\text{ mm Hg}$, pulse is $102\text{/min}$, and respiratory rate is $22\text{/min}$. Physical examination of the posterior thorax reveals localized dullness to percussion over the right lower lung zone. While auscultating this specific area, the clinician asks the patient to continuously vocalize the vowel "E", which is heard through the stethoscope as a distinct, nasal "A" sound. Which of the following additional physical examination findings is most likely to be elicited over this precise anatomical area?

A $62$-year-old woman comes to the clinic for a routine wellness examination. She reports feeling generally well, though she has experienced mild fatigue and occasional constipation over the past few months. She takes no medications and has no significant past medical history. Vital signs are within normal limits. Laboratory studies show:

Which of the following is the most likely diagnosis based on these laboratory findings?

A 32-year-old man presents to the primary care clinic requesting comprehensive sexually transmitted infection (STI) screening. He recently entered a new relationship and wants to ensure he is healthy. He has no current symptoms, and a detailed physical examination reveals no oral, genital, or anal lesions, nor any rashes. The clinic's laboratory employs the reverse sequence diagnostic algorithm for syphilis screening. For this patient, the initial screening test returns a reactive result, while the subsequent reflex test returns a nonreactive result, prompting a third laboratory test.

Arrange the following laboratory tests in the exact chronological sequence they would be performed for this patient according to the reverse sequence algorithm.

An attending physician is discussing the precise mechanisms of advanced immunomodulatory therapies with the medical team. Match each biological agent with its correct molecular target and primary immunopathologic mechanism of action.

A $22$-year-old female college student is evaluated in the emergency department for severe, colicky abdominal pain, intractable nausea, and new-onset weakness in her bilateral upper extremities. She has a history of similar, albeit milder, abdominal pain episodes over the past $2$ years. Her vital signs are notable for a heart rate of $122$/min and a blood pressure of $168/105$ mm Hg. Physical examination demonstrates generalized abdominal tenderness without rigidity or rebound. Initial laboratory workup reveals a serum sodium of $126$ mEq/L, with a normal lipase level, liver transaminases, and complete blood count. An abdominal ultrasound is unremarkable. Upon returning from the radiology suite, the nurse notes that the patient's urine in the bedside collection container has developed a deep red-purple hue after being exposed to ambient light. Arrange the following laboratory investigations in the most evidence-based sequential order for the diagnostic workup of this patient's suspected metabolic disorder.

Match each laboratory profile with its most likely clinical diagnosis.

A 22-year-old female presents to the outpatient clinic reporting intermittent muscle cramping and tingling in her fingertips over the past several months. She has a history of mild intellectual disability but currently takes no medications. Vital signs are within normal limits. Physical examination reveals short stature, a round face, and shortened fourth and fifth metacarpals on both hands. Tapping the facial nerve anterior to the earlobe elicits twitching of the ipsilateral facial muscles. Laboratory studies show:

Which of the following cellular mechanisms best explains this patient's clinical and laboratory findings?

A 42-year-old man comes to the clinic for a follow-up evaluation. Two weeks ago, he was noted to have an elevated serum calcium level on a routine comprehensive metabolic panel obtained for a life insurance policy. He feels well and has no fatigue, abdominal pain, bone pain, or changes in bowel habits. His only medical history is mild hypertension, for which he has been taking amlodipine for three years. He does not take any over-the-counter supplements. He is adopted and does not know his family medical history. Blood pressure is 128/82 mm Hg, and pulse is 72/min. Physical examination is unremarkable.

Laboratory results are as follows:

Based on the laboratory results, which of the following is the most likely underlying mechanism for this patient's findings?