WBR1066
| Author | [[PageAuthor::Mohamed Moubarak, M.D. [1]]] |
|---|---|
| Exam Type | USMLE Step 3 |
| Main Category | Emergency Room |
| Sub Category | Electrolytes |
| Prompt | A 67 year-old male brought to ED by his son after he became disoriented and confused. His son mentioned that he is living alone, ¬¬and he was okay at his last visit 2 days ago, and he showed some seizures while on the way. The patient has a past medical history of alcoholic liver cirrhosis. On examination, the patient is confused, disoriented to time and place. His blood pressure is 90/60 mmHg, pulse 120 beat per minute, respiration 23/m, and temperature 37 C. Cardiopulmonary exam was unremarkable. Abdominal exam shows tense ascites and a shrunken liver. Lower extremities had 3+ pitting edema. His laboratory tests are shown below.
• Sodium 110 (N: 135-146 mmol/L) • Potassium 3.8 (N: 3.5-5.3 mmol/L) • Glucose 100 (N: 70-110 mg/dl) • Chloride 98 (N: 98-108 mmol/L) • Total CO2 25 (N: 23-27 mmol/L) Which of the following is the cause of the patient’s altered mental status? |
| Answer A | Hypotension |
| Answer A Explanation | Incorrect
The patient blood pressure is borderline, instead hyponatremia lead to increased water shifting into the brain, resulting in cerebral edema. |
| Answer B | Cerebral edema |
| Answer B Explanation | Correct
Hyponatremia, which can lead to increased water shifting into the brain, resulting in cerebral edema. |
| Answer C | Stroke |
| Answer C Explanation | Incorrect
Nothing in this patient history suggest the diagnosis of stroke |
| Answer D | Central pontine myelinolysis |
| Answer D Explanation | Incorrect
Central pontine myelinolysis is a potentially neurologic complication that can result from the treatment of hyponatremia, not hyponatremia itself. |
| Answer E | Hypoglycemia |
| Answer E Explanation | Incorrect
This patient doesn’t have hypoglycemia |
| Right Answer | B |
| Explanation | The patient has hyponatremia, which can lead to increased water shifting into the brain, resulting in cerebral edema. Educational Objective: Severe hyponatremia may cause osmotic shift of water from the plasma into the brain cells. Typical symptoms include nausea, vomiting, headache and malaise. As the hyponatremia worsens, confusion, diminished reflexes, convulsions, stupor or coma may occur. |
| Approved | No |
| Keyword | [[WBRKeyword::Hyponatremia]] |
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