NOTE: this is a USMLE Consult-"inspired" question, so look away if you plan on using USMLE Consult as a measure of your progress.
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A 25-year-old woman undergoes neurosurgery for a subarachnoid hemorrhage after being involved in a motor vehicle collision. Thirty hours after the surgery, she has extreme thirst, headache, and nausea.
Laboratory results:
Blood Studies
White Blood Cell: 5.3*10^3mm3
Red Blood Cell: 4.3* 10^6mm3
Hemoglobin: 9.6 gm/dL
Hematocrit: 28.1
Platelets: 277*10^3mm3
Sodium: 131.mEq/L
Potassium: 4.3 mEq/L
Chloride: 104 mEq/L
CO: 2104 mEq/L
Blood urea nitrogen: 9 mg/dL
Creatinine: 0.6 mg/dL
Blood glucose: 99 mg/dL
Calcium: 9.2 mg/dL
Total Protein: 7.3 gm/dL
Albumin: 4.4 gm/dL
Bilirubin: 0.7 mg/dL
Alkaline phosphatase: 120 IU/L
ALT: 33 IU/L
AST: 16 IU/L
Urinary Data
Volume (since operation): 20 mL
Osmolality: 70 mOsm
pH: 6.0
Specific Gravity: 1.010
Ketones: Negative
Glucose: Trace
Blood: Negative
Protein: Trace
Nitrite: Negative
Leukocyte esterase: Negative
Which of the following is the most likely explanation for her condition?
A. Increased extracellular fluid volume
B. Increased extracellular fluid acid
C. Increased extracellular fluid potassium
D. Increased urinary fluid volume
E. Increased urinary fluid acid
F. Increased urinary fluid potassium
(please explain your choice).
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A 25-year-old woman undergoes neurosurgery for a subarachnoid hemorrhage after being involved in a motor vehicle collision. Thirty hours after the surgery, she has extreme thirst, headache, and nausea.
Laboratory results:
Blood Studies
White Blood Cell: 5.3*10^3mm3
Red Blood Cell: 4.3* 10^6mm3
Hemoglobin: 9.6 gm/dL
Hematocrit: 28.1
Platelets: 277*10^3mm3
Sodium: 131.mEq/L
Potassium: 4.3 mEq/L
Chloride: 104 mEq/L
CO: 2104 mEq/L
Blood urea nitrogen: 9 mg/dL
Creatinine: 0.6 mg/dL
Blood glucose: 99 mg/dL
Calcium: 9.2 mg/dL
Total Protein: 7.3 gm/dL
Albumin: 4.4 gm/dL
Bilirubin: 0.7 mg/dL
Alkaline phosphatase: 120 IU/L
ALT: 33 IU/L
AST: 16 IU/L
Urinary Data
Volume (since operation): 20 mL
Osmolality: 70 mOsm
pH: 6.0
Specific Gravity: 1.010
Ketones: Negative
Glucose: Trace
Blood: Negative
Protein: Trace
Nitrite: Negative
Leukocyte esterase: Negative
Which of the following is the most likely explanation for her condition?
A. Increased extracellular fluid volume
B. Increased extracellular fluid acid
C. Increased extracellular fluid potassium
D. Increased urinary fluid volume
E. Increased urinary fluid acid
F. Increased urinary fluid potassium
(please explain your choice).