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Category: Critical Care Medicine-Renal, Electrolyte and Acid Base Disorders--->Sodium
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Question 1#Print Question

A 78-year-old man is brought to the hospital after being found down by his daughter at his home this morning. He was functional at baseline and last seen normal yesterday. He is a life-time smoker with chronic obstructive pulmonary disease (COPD) and was recently diagnosed with lung cancer. On physical examination, he is lethargic, has unsteady gait, and is confused. His temperature is 37.4°C, blood pressure is 127/94 mm Hg, pulse rate is 74 beats/min, and respiratory rate is 11 breaths/min. On examination, he has a normal jugular venous pressure, but he has decreased air entry at the lung bases. A CT head obtained shows age-related atrophic changes. Laboratory studies obtained are as follows:

  • Sodium 120 mEq/L (mmol/L)
  • BUN 9 mg/dL
  • Bicarbonate 30 mmol/L
  • Creatinine 1.0 mg/dL
  • Urine osmolality 275 mOsm/kg H2O
  • Urine sodium 45 mEq/L (mmol/L)
  • Serum osmolality 264 mOsm/kg H2O
  • Glucose 84 mg/dL (4.6 mmol/L)

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

A. Fluid restriction to 800 mL
B. Desmopressin
C. Isotonic saline infusion
D. Tolvaptan
E. Hypertonic saline infusion


Question 2#Print Question

A 17-year-old college student is admitted to the hospital after sustaining a traumatic hit to the head during football practice, resulting in subdural hemorrhage. Upon arrival, his Glasgow Coma Scale is 4. He is started on hypertonic saline and undergoes emergent neurosurgical intervention. His exam remains unchanged overnight, but during morning rounds, the nurse reports that his urine output increased to over 300 mL/h. 

Laboratory studies obtained show:

  • serum sodium 167 mEq/L
  • specific gravity 1.013
  • random urine sodium 55 mEq/L (mmol/L)
  • random urine creatinine 51 mg/dL
  • urine osmolality 199 mOsm/kg H2O
  • serum osmolality 338 mOsm/kg H2O

Which is the MOST likely cause of his increased urine output? 

A. Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
B. Central diabetes insipidus (DI)
C. Cerebral salt wasting (CSW) syndrome
D. Nephrogenic diabetes insipidus (NDI)
E. Osmotic diuresis


Question 3#Print Question

A 68-year-old man presents to his primary care physician complaining of frequent urination at night. He reports a strong urinary stream without any feeling of incomplete emptying. His medications include aspirin, pravastatin, lithium, and amlodipine. On physical examination, he is afebrile, his blood pressure 138/75 mm Hg, pulse rate 74 beats/min, and respiratory rate 18 breaths/min.

Which of the following laboratory studies are MOST consistent with the patient’s clinical presentation?

A. A
B. B
C. C
D. D


Question 4#Print Question

A 58-year-old woman with past medical history of alcohol abuse and bipolar schizophrenia presents to the hospital after a fall complicated by numerous rib fractures seen on chest x-ray. She is currently not taking any medications. On physical examination, her temperature is 37.1°C, blood pressure is 138/88 mm Hg, pulse rate is 99 beats/min, and respiratory rate is 14 breaths/min, oxygen saturation is 95% on room air. Her neurological, cardiovascular, and abdominal examinations are normal. She exhibits tenderness to palpation over the left chest wall with decreased bibasilar breath sounds. Her chemistry panel is as follows: 

  • Sodium 122 mEq/L (mmol/L)
  • Potassium 2.8 mEq/L (mmol/L)
  • BUN 5 mg/dL
  • Creatinine 0.7 mg/dL
  • Urine osmolality 117 mOsm/kg
  • Urine sodium 18 mEq/L (mmol/L)
  • Serum osmolality 266 mOsm/kg
  • Glucose 105 mg/dL
  • Thyroid stimulating hormone 2.20 mIU/L
  • Morning cortisol 16 µg/dL
  • Total cholesterol 140 mg/dL
  • HDL cholesterol 55 mg/dL
  • LDL cholesterol 124 mg/dL
  • Triglycerides 162 mg/dL

What is the MOST appropriate management of her hyponatremia?

A. Conivaptan
B. Desmopressin
C. Normal saline infusion
D. Fluid restriction
E. Observation with repeat laboratory testing in 4 to 6 hours


Question 5#Print Question

A 62-year-old woman is brought to the hospital with sudden onset headache followed by nausea and vomiting. Upon arrival to the emergency room, she is lethargic with a Glasgow Coma Scale of 5. Significant vital signs include a blood pressure of 220/130 mm Hg. She is emergently intubated. CT scan of the head reveals subarachnoid hemorrhage in the basilar cisterns. She undergoes placement of a right frontal extraventricular device and coiling with improvement of her neurological examination. Over the following days, she is weaned off propofol. However, on the seventh day, her urine output increases to 4 L/d and she becomes hypotensive with blood pressure of 89/60 mm Hg and pulse rate of 118 beats/min. Laboratory data show:

  • hyponatremia with a sodium level of 130 mEq/L
  • potassium of 3.3 mEq/L
  • plasma osmolality of 269 mOsm/kg
  • urine sodium concentration of 71 mEq/L
  • urine osmolality of 93 mmol/L
  • glucose 172 mg/dL
  • TSH 3.1 mIU/L
  • triglyceride of 118 mg/dL

What is the MOST likely cause for the patient’s acute changes? 

A. CSW syndrome
B. Central DI
C. Osmotic diuresis
D. SIADH
E. Pseudohyponatremia




Category: Critical Care Medicine-Renal, Electrolyte and Acid Base Disorders--->Sodium
Page: 1 of 2