Free Internal Medicine Sample Questions
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Your First Free Internal Medicine Sample Question
A 23-year-old male presents to the emergency department via altered mental status. He states repeatedly that the people in the television are telling him to join them. His friends, who accompany him, mention he has been acting very strangely over the last few months, isolating himself from others and ranting about satellites and cell phone towers. He was the valedictorian of his high school and is currently working on his master’s degree. They deny any history of medical conditions, medications, drug use, or encounters with the law.
Vital signs are unremarkable. Physical examination reveals a well-developed male, who appears drowsy. Mucous membranes are moist. Heart is regular rate and rhythm, and lungs are clear to auscultation. Abdomen is soft and nontender to palpation. There are no rashes or skin lesions. Laboratories studies reveal the following:
Laboratory studies:
| Parameter | Patient Value | Reference Range |
| Leukocyte count (cells/μL) | 16000 | 4000-10000 |
| Hemoglobin (g/dL) | 15 | 14-18 |
| Platelets (cells/μL) | 220000 | 150000-450000 |
| Sodium (mEq/L) | 115 | 136-145 |
| Potassium (mEq/L) | 4.0 | 3.5-5.0 |
| Chloride (mEq/L) | 109 | 98-106 |
| Bicarbonate (mEq/L) | 19 | 23-28 |
| Blood urea nitrogen (mg/dL) | 21 | 8-20 |
| Creatinine (mg/dL) | 1.2 | 0.7-1.5 |
| Albumin (g/dL) | 4.0 | 3.5-5.5 |
| Glucose, fasting (mg/dL) | 200 | 70-99 |
| Serum osmolarity (mOsm/kg H2O) | 250 | 280-300 |
| Urine sodium (mEq/L) | 10 | varies |
| Urine osmolarity (mOsm/kg H2O) | 30 | 38-1400 |
Which of the following is the most likely etiology of this patient’s abnormal laboratory findings?
- A. Acute kidney injury
- B. Dehydration
- C. Excessive water intake
- D. MDMA use
- E. Syndrome of inappropriate antidiuretic hormone secretion
The Answer and Explanation
Did you get it right? The correct answer is: C
The majority of clinically relevant hyponatremia is hypotonic. This patient appears to be developing schizophrenia and is exhibiting paranoid delusions with auditory hallucinations, along with progressive social isolation. He is also male and in the third decade of his life, two additional risk factors for the development of schizophrenia. This underlying psychiatric condition predisposes patients to polydipsia, which can cause hypotonic hyponatremia. His lab studies also point to excessive water intake: urine osmolarity is 30 mOsm/kg H20 and urine sodium < 20 mEq/L, which indicate dilute urine from excessive water intake.
Incorrect Answer Explanations
Answer A: Acute kidney injury causes a hypotonic hyponatremia. Urine osmolarity is typically > 100 mOsm/kg H20, patients appear volume-overloaded, and urine sodium is < 20 mEq/L. Furthermore, this patient’s creatinine is not elevated, and he is not in renal failure.
Answer B: There is no reason to think this patient is dehydrated. He is euvolemic on physical exam, and not tachycardic or hypotensive. Furthermore, there is nothing mentioned in the history that would allude to etiologies that could cause dehydration. These patients will usually have a urine osmolarity > 100 mOsm/kg H20 and a urine sodium < 20 mEq/L (indicating pre-renal azotemia).
Answer D: MDMA (ecstasy) use can cause hypotonic hyponatremia and, if not managed early, can lead to coma and death. The hyponatremia is caused by a combination of polydipsia and the direct effect of the drug, which can lead to elevated antidiuretic hormone (ADH) levels. Because of the elevated ADH levels, the urine is usually concentrated (similar to an SIADH picture), with a urine osmolarity typically > 100 mOsm/kg H2O.
Answer E: Once you confirm primary hyperaldosteronism, you send the patient for a CT of the abdomen and pelvis to look for adrenal adenoma or carcinoma. This clinical scenario is indicative of non-mineralocorticoid excess, not primary hyperaldosteronism.
Bottom Line
Psychogenic polydipsia can cause hyponatremia, in which urine osmolarity is typically < 100 mOsm/kg H2O and urine sodium is < 20 mEq/L.
For more information, see:
Evaluation of patients with polyuria. On UpToDate.
Pathophysiology and etiology of the syndrome of inappropriate antidiuretic hormone secretion (SIADH). On UpToDate.Verbalis JG. Posterior pituitary. Goldman-Cecil Medicine. 26th Ed. Philadelphia: Saunders, 2020. 1456-1462. Print.
Your Second Free Internal Medicine Sample Question
A 19-year-old woman presents to the emergency department for altered mental status. Her college roommate noticed that she was agitated and confused 1 hour after dinner. She reports the patient has been feeling depressed due to her mounting course load and distance from her family at home. Her past medical history is unknown, and she denies the use of alcohol, illicit substances, tobacco, or sexual activity.
Her temperature is 38.0°C (100.4°F), pulse rate is 92/min, respiratory rate is 36/min, and blood pressure is 104/76 mm Hg. On physical examination, the patient is agitated but cooperative. She grimaces and places her hands over her ears. Her mucous membranes are moist, and her pupils are equal, round, and reactive to light. She is breathing deeply and rapidly and has crackles bilaterally on auscultation. Laboratories studies reveal the following:
Laboratory studies:
| Parameter | Patient Value | Reference Range |
| Glucose (mg/dL) | 67 | 70-99 |
| Arterial pH | 7.54 | 7.36-7.44 |
| PaCO2 (mm Hg) | 31 | 38-42 |
| PaO2 (mm Hg) | 86 | 75-100 |
| HCO3 (mmol/L) | 21 | 23-26 |
Which one of the following is the most appropriate next step in management?
- A. Activated charcoal
- B. Atropine
- C. Deferoxamine
- D. Ethanol
- E. Lorazepam
The Answer and Explanation
Did you get it right? The correct answer is: A
The patient in this scenario is likely suffering from acute salicylate toxicity. On the basis of her arterial blood gas (ABG) results, this patient has an alkalosis (pH > 7.4). Her PaCO2 is low (< 40 mm Hg), and she has increased her minute ventilation by increasing both her tidal volume and respiratory rate, making this a respiratory alkalosis. Given the acute onset, one should have a high index of suspicion for toxic ingestion.
Tinnitus is classic for salicylate toxicity. Other symptoms are relatively nonspecific and include nausea, vomiting, seizures, and fever. Salicylate toxicity can present as a high-anion-gap metabolic acidosis, particularly in children, or respiratory alkalosis, especially within the first few hours after ingestion in adolescents and adults. Alternatively, if the ingestion occurred several hours ago, patients may have near-normal pH with low bicarbonate and/or low PaCO2 levels.
Treatment of salicylate toxicity includes supporting airway, breathing, and circulation with intubation and/or vasopressors as needed. Other modalities are directed at clinical sequelae (ex. sodium bicarbonate to alkalinize the urine, supplemental glucose for hypoglycemia, etc.). Activated charcoal binds aspirin very well and should be administered in patients who present within 2 hours of ingestion and are alert and cooperative or intubated with an orogastric tube. Hemodialysis is used in severe cases.
Incorrect Answer Explanations
Answer B: Atropine is an antidote for organophosphate poisoning, which presents with salivation, lacrimation, urination, diarrhea, gastrointestinal upset, and emesis.
Answer C: Deferoxamine is used for iron poisoning, which has a nonspecific acute presentation including gastrointestinal upset and nausea. Respiratory alkalosis is not common.
Answer D: Ethanol is used in methanol poisoning, which is a cause of an anion gap metabolic acidosis and rarely associated with respiratory alkalosis.
Answer E: Lorazepam may be used in patients presenting with seizures, which may occur in patients with salicylate toxicity, but they are not used as seizure prophylaxis in patients who are not actively seizing.
Bottom Line
Salicylate toxicity can present as a high-anion-gap metabolic acidosis, respiratory alkalosis, or near-normal pH with low bicarbonate and/or low PaCO2 levels. If the ingestion occurred recently, activated charcoal may be an important component of treatment.
For more information, see:
Nelson LS. “Acute poisoning.” Goldman-Cecil Medicine. 26th ed. Philadelphia: Saunders, 2020. 664-679. Print.
“Salicylate (aspirin) poisoning in adults.” On UpToDate.
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