Internal Medicine

Match each patient's serum and urine laboratory profile with the most likely underlying diagnosis. Assume all patients have a normal clinical volume status (euvolemia) unless otherwise implied by the laboratory values.

A $24$-year-old male presents to the clinic with a $3$-day history of severe abdominal cramping and diarrhea. He reports that the diarrhea was initially watery but has become frankly bloody over the past $24$ hours. He has not traveled recently but frequently eats at a local food truck that serves hamburgers. His temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure is $112/74\text{ mm Hg}$, and pulse is $92\text{/min}$. Physical examination reveals a non-distended abdomen with moderate, diffuse tenderness to palpation, but no rebound or guarding. Bowel sounds are hyperactive. Laboratory studies show a leukocyte count of $9,500/\text{mm}^3$, hemoglobin of $13.8\text{ g/dL}$, and a platelet count of $185,000/\text{mm}^3$. Renal function panel is currently within normal limits. Stool testing for ova and parasites is negative, and stool culture is pending. Which of the following is the most appropriate next step in the management of this patient?

Match each patient's clinical presentation of chronic gastrointestinal dysfunction with the most accurate underlying pathophysiologic mechanism or etiology.

An 18-year-old college freshman visits the campus health center complaining of a constant "ringing" sound in his ears, generalized nausea, and three episodes of nonbloody emesis since last night. He states he has been feeling extremely overwhelmed by his upcoming final examinations. On physical examination, he appears anxious and is breathing rapidly and deeply.

Vital signs:
Temperature: $37.8^\circ C$ ($100.0^\circ F$)
Blood pressure: $112/70$ mm Hg
Pulse: $114$/min
Respirations: $28$/min

Laboratory results:
Serum chemistry:
Sodium: $140$ mEq/L
Potassium: $3.8$ mEq/L
Chloride: $104$ mEq/L
Bicarbonate: $14$ mEq/L
Blood urea nitrogen: $18$ mg/dL
Creatinine: $0.8$ mg/dL

Arterial blood gas (room air):
pH: $7.47$
$PaCO_2$: $20$ mm Hg
$PaO_2$: $98$ mm Hg

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

A 45-year-old man is evaluated in the intensive care unit for worsening kidney function. Three days ago, he was admitted with severe sepsis secondary to right lower lobe pneumonia and required vasopressor support for 48 hours. His blood pressure is now stable off vasopressors. Urine output over the last 12 hours has been 250 mL.

Laboratory studies are obtained:

What is the patient's fractional excretion of sodium ($Fe_{Na}$) expressed as a percentage?

A 28-year-old pregnant woman (G1P0 at 26 weeks gestation) is evaluated in the acute care clinic for a 2-hour history of severe breathlessness, palpitations, and an inability to lie flat. She recently immigrated from Southeast Asia and reports experiencing recurrent, untreated sore throats during her childhood.

Current vital signs reveal a temperature of 37.1°C (98.8°F), blood pressure of 112/68 mmHg, and a respiratory rate of 26/min. Her pulse is 135/min and irregularly irregular. Pulse oximetry demonstrates an oxygen saturation of 91% on ambient air.

Physical examination highlights prominent jugular venous distention. Cardiac auscultation is notable for a loud first heart sound ($S_1$), a sharp high-pitched sound immediately following the second heart sound ($S_2$), and a low-pitched, rumbling diastolic murmur heard optimally at the cardiac apex. Pulmonary auscultation reveals bilateral crackles extending up to the mid-lung fields.

A 12-lead electrocardiogram confirms an irregularly irregular rhythm characterized by narrow QRS complexes and an absence of distinct P waves.

Which of the following is the most appropriate initial pharmacological step to alleviate this patient's acute respiratory distress?

An 81-year-old man residing in a skilled nursing facility is evaluated during a routine clinic visit. The patient has advanced Alzheimer dementia and is completely bedbound. He has an indwelling urethral catheter that was placed 8 months ago for chronic urinary retention. The facility staff report that for the past 4 days, the urine in his collection bag has appeared persistently cloudy and malodorous. The patient has not exhibited any behavioral changes, increased agitation, or signs of physical discomfort. His temperature is $36.9^\circ\text{C}$ ($98.4^\circ\text{F}$), blood pressure is $132/82 \text{ mm Hg}$, pulse is $74\text{ /min}$, and respiratory rate is $16\text{ /min}$. Physical examination reveals a soft, non-tender abdomen with no suprapubic or costovertebral angle tenderness.

Laboratory studies show:
Leukocyte count: $6,800/\text{mm}^3$

Urinalysis:
- Appearance: Cloudy
- Leukocyte esterase: Positive
- Nitrites: Positive
- WBCs: $45/\text{hpf}$

Urine culture: $>100,000 \text{ CFU/mL}$ of *Klebsiella pneumoniae*

Antimicrobial susceptibilities for the isolate are as follows:

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

A 56-year-old man is brought to the emergency department via ambulance due to vomiting large amounts of bright red blood. He has a history of alcohol-associated cirrhosis. En route to the hospital, he had two more episodes of massive hematemesis. On arrival, he is somnolent, groans to painful stimuli, and is unable to follow commands. His temperature is 36.5°C (97.7°F), blood pressure is 78/45 mmHg, heart rate is 132/min, and respiratory rate is 24/min. Pulse oximetry is 92% on room air. Physical examination is notable for jaundice, spider angiomas on the chest, and a distended abdomen with shifting dullness.

Arrange the following interventions in the most appropriate sequential order for the acute management of this patient's condition.

A 58-year-old man is brought to the emergency department by emergency medical services after vomiting a large amount of bright red blood. He has a past medical history of alcoholic cirrhosis and admits to recent noncompliance with his home medications. On arrival, he is lethargic but arousable. His temperature is 36.5°C (97.7°F), blood pressure is 88/54 mmHg, heart rate is 122/min, and respiratory rate is 22/min. Physical examination reveals scleral icterus, multiple spider angiomas on the upper chest, and a distended abdomen with shifting dullness. His extremities are cool and clammy. Two large-bore peripheral intravenous lines are immediately established, and rapid resuscitation with isotonic crystalloid is initiated. Blood type and crossmatch are sent to the laboratory. Which of the following is the most appropriate next step in the acute medical management of this patient?

A 42-year-old woman is brought to the emergency department with sudden-onset shortness of breath and right-sided pleuritic chest pain. Her medical history includes ulcerative colitis, and she reports experiencing a severe disease flare with 6 to 8 watery bowel movements daily for the past week. Vital signs show a temperature of 37.6°C (99.7°F), heart rate of 115/min, blood pressure of 112/68 mm Hg, and respiratory rate of 28/min. Pulse oximetry is 88% on room air. Physical examination reveals clear lungs bilaterally but right calf swelling and tenderness. A computed tomography pulmonary angiogram confirms a segmental pulmonary embolism. Laboratory studies are as follows:

Arterial blood gas (room air):
pH: 7.39
$\text{PaCO}_2$: $17 \text{ mm Hg}$
$\text{PaO}_2$: $55 \text{ mm Hg}$

Based on these results, which of the following best characterizes this patient's acid-base status?

Match each of the following clinical, laboratory, or histopathologic presentations to the most appropriate malabsorptive disorder.

Select the most appropriate first-line antimicrobial therapy for each of the following patient scenarios.

Emergency medical services transport a $24$-year-old man to the acute care bay for profound respiratory distress. He has a history of poorly controlled asthma and ran out of his fluticasone inhaler two weeks ago. Upon arrival, the patient is extremely agitated and diaphoretic, using prominent accessory muscles of respiration. Auscultation of the lungs reveals loud, diffuse expiratory wheezing bilaterally. He is immediately treated with continuous nebulized albuterol, ipratropium, and intravenous methylprednisolone. Reassessment one hour later reveals a somnolent patient who is difficult to arouse. His temperature is $37.1^{\circ}\text{C}$ ($98.8^{\circ}\text{F}$), blood pressure is $118/72$ mm Hg, pulse is $124$/min, and respirations are $14$/min. Oxygen saturation is $88\%$ on a $15$ L/min non-rebreather mask. Pulmonary examination now demonstrates markedly diminished breath sounds bilaterally with minimal wheezing. Arterial blood gas analysis on the current oxygen setting shows:

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

A 48-year-old man is evaluated in the intensive care unit for persistent hypoxemia. He was admitted 2 days ago for severe acute pancreatitis and was intubated 24 hours ago due to progressive respiratory failure. He is currently sedated and paralyzed. His temperature is $38.2^\circ\text{C}$ ($100.8^\circ\text{F}$), blood pressure is $112/68\text{ mm Hg}$, and pulse is $114\text{/min}$. Central venous pressure is $6\text{ mm Hg}$.

Chest radiograph shows diffuse, bilateral alveolar opacities without cardiomegaly.

Mechanical ventilation is set to assist-control volume mode with the following parameters:

* Tidal volume: $420\text{ mL}$ ($6\text{ mL/kg}$ of predicted body weight)
* Respiratory rate: $24\text{/min}$
* Fraction of inspired oxygen (FiO $_2$): $0.70$
* Positive end-expiratory pressure (PEEP): $5\text{ cm H}_2\text{O}$

Arterial blood gas analysis:
* pH: $7.31$
* PaCO $_2$: $34\text{ mm Hg}$
* PaO $_2$: $54\text{ mm Hg}$
* HCO $_3^-$: $17\text{ mEq/L}$

The patient's current oxygen saturation is $85\%$, and plateau pressure is $22\text{ cm H}_2\text{O}$. Which of the following is the most appropriate next step in the management of this patient's hypoxemia?

A 35-year-old man is brought to the urgent care clinic by his roommate because of confusion and an inability to keep fluids down for the past 4 days. The roommate reports the patient has a history of type 1 diabetes mellitus but lost his insurance recently and started rationing his insulin. Over the last 96 hours, the patient has had severe nausea and vomited more than 10 times daily. He appears lethargic and is difficult to arouse. His temperature is 37.1°C (98.8°F), blood pressure is 92/56 mm Hg, pulse is 124/min, and respirations are 16/min. Examination shows deeply sunken eyes, dry oral mucosa, and delayed capillary refill.

Analysis of these laboratory findings most accurately indicates which of the following underlying acid-base disturbances?

A 28-year-old man is brought to the outpatient clinic by his partner due to profound fatigue, a $9\text{ kg}$ ($19.8\text{ lb}$) weight gain, and depressive symptoms that have progressively worsened over the past 6 months. Nine months ago, the patient sustained a severe traumatic brain injury with a basilar skull fracture following a motorcycle collision, requiring a 3-week stay in the intensive care unit. He currently takes no medications. Vital signs show a blood pressure of $102/64\text{ mmHg}$ and a pulse of $54\text{/min}$. Physical examination reveals dry skin, delayed relaxation of deep tendon reflexes, and diminished axillary and pubic hair. Visual field testing is normal.

Laboratory studies show:
* Thyroid-stimulating hormone (TSH): $0.9 \text{ \mu U/mL}$ (Reference: $0.4-4.2 \text{ \mu U/mL}$)
* Free T4: $0.5 \text{ ng/dL}$ (Reference: $0.8-1.8 \text{ ng/dL}$)
* Morning serum cortisol: $3.4 \text{ \mu g/dL}$ (Reference: $5-25 \text{ \mu g/dL}$)

Which of the following is the most likely cause of this patient's abnormal laboratory findings?

A $66$-year-old man is evaluated in the emergency department for sudden, severe difficulty breathing that awoke him from sleep. The patient states he felt as though he were suffocating and developed a cough producing frothy sputum. His past medical history is notable for a $45$-pack-year smoking habit and an anterior ST-segment elevation myocardial infarction three years prior, for which he underwent percutaneous coronary intervention. His daily medications include low-dose aspirin, carvedilol, and rosuvastatin, but he admits to running out of these medications two weeks ago.

Vital signs reveal a temperature of $37.0^\circ\text{C}$ ($98.6^\circ\text{F}$), blood pressure of $172/96\text{ mmHg}$, heart rate of $112/\text{min}$, and respiratory rate of $26/\text{min}$. Pulse oximetry shows an oxygen saturation of $87\%$ on room air.

On physical examination, the patient is in severe respiratory distress and utilizing accessory muscles. Jugular venous distention is prominent up to the angle of the mandible while the patient is sitting upright. Pulmonary auscultation demonstrates prolonged expiratory phases with loud, diffuse wheezing in all lung fields, alongside bilateral crackles at the lung bases. Cardiac auscultation reveals a regular, rapid rhythm with a distinct low-frequency diastolic sound heard just after S2. There is $2+$ pitting edema extending to the mid-calves bilaterally.

An arterial blood gas analysis on room air shows:
pH: $7.28$
PaCO $_2$: $56\text{ mmHg}$
PaO $_2$: $58\text{ mmHg}$
HCO $_3^-$: $25\text{ mEq/L}$

Which of the following is the most appropriate initial pharmacologic step in managing this patient's condition?

A $54$-year-old male with known decompensated cirrhosis is brought to the emergency room after experiencing two episodes of large-volume, bright red hematemesis at home. Upon arrival, he is pale and lethargic but is able to converse and is protecting his airway. Vital signs reveal a blood pressure of $88/56$ mm Hg, heart rate of $118$/min, respiratory rate of $18$/min, and oxygen saturation of $96\%$ on ambient air. Physical examination demonstrates scleral icterus, caput medusae, and shifting dullness. Arrange the following interventions in the most appropriate sequential order for the acute management of this patient.

A 52-year-old woman is evaluated in the hospital for a new-onset fever. She was admitted $12$ days ago for induction chemotherapy for acute myeloid leukemia. Her temperature is $38.8^\circ\text{C}$ ($101.8^\circ\text{F}$), blood pressure is $114/72$ mm Hg, pulse is $98$/min, and respirations are $16$/min. Oxygen saturation is $98\%$ on room air. Physical examination reveals a right internal jugular central venous catheter; the insertion site is clean, dry, and without erythema or tenderness. There is no oral thrush or mucositis. Lung fields are clear to auscultation. The abdomen is soft and non-tender. Skin examination shows no rashes or induration.

Laboratory studies show:
Leukocyte count: $800/\text{mm}^3$
Absolute neutrophil count: $120/\text{mm}^3$
Hemoglobin: $8.4$ g/dL
Platelet count: $45,000/\text{mm}^3$

Urinalysis is negative for leukocyte esterase and nitrites. Chest radiography reveals no infiltrates. Blood and urine cultures are obtained. Which of the following is the most appropriate empiric pharmacotherapy for this patient?

A $52$-year-old man is evaluated in the intensive care unit on the third day of hospitalization for severe acute pancreatitis. The patient was initially admitted with severe epigastric pain and a serum lipase level of $3,500\text{ U/L}$. Over the first $48\text{ hours}$, he received aggressive fluid resuscitation with $12\text{ L}$ of intravenous lactated Ringer solution. Today, the nursing staff reports that he appears increasingly lethargic. His temperature is $38.7^\circ\text{C}$ ($101.7^\circ\text{F}$), blood pressure is $108/65\text{ mmHg}$, pulse is $118/\text{min}$, and respirations are $24/\text{min}$. Physical examination shows generalized pitting edema and clear lungs bilaterally. The abdomen is significantly distended and diffusely tender to palpation without rigidity or guarding. Bowel sounds are absent.

Laboratory results are as follows:
Leukocyte count: $18,500/\text{mm}^3$
Blood urea nitrogen: $32\text{ mg/dL}$ (was $18\text{ mg/dL}$ on admission)
Serum creatinine: $1.9\text{ mg/dL}$ (was $0.9\text{ mg/dL}$ on admission)
Serum sodium: $138\text{ mEq/L}$
Serum potassium: $4.1\text{ mEq/L}$
Serum chloride: $104\text{ mEq/L}$
Serum bicarbonate: $16\text{ mEq/L}$

Arterial blood gas analysis on room air shows a pH of $7.32$, $\text{PaCO}_2$ of $30\text{ mmHg}$, and $\text{PaO}_2$ of $78\text{ mmHg}$.

A contrast-enhanced CT scan of the abdomen reveals diffuse enlargement of the pancreas with non-enhancement of approximately $50\%$ of the parenchyma, consistent with severe pancreatic necrosis. There are large peripancreatic fluid collections but no retroperitoneal gas is visualized.

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