Hypernatremia MCQ

1) A 42-year-old ultra marathon runner collapsed at the finish of the 100-mile race. She was confused and knew only her name. Blood pressure was 90/60 mmHg and pulse was 130 beats/minute; she could not stand up. No pre-marathon weight was available. Serum sodium concentration was 163 mEq/L. The most likely underlying cause of the hypernatremia is:
a. Loss of hypotonic fluid across skin
b. Lithium use
c. Hereditary nephrogenic diabetes insipidus
d. Pregnancy with increased placental vasopresinase activity

2) A 40-year-old man with a yet undiagnosed systemic disease, including pulmonary lesions, presents with increasing thirst, polydipsia, polyuria, and a serum sodium concentrate of 152 mEq/L. Simultaneous urine osmolality was 100 mosm/kg. He takes no mediation. The most likely systemic disease responsible for the hypernatremia is:
a. Diabetes mellitus
b. Neurosarcoidosis
c. Adrenal insufficiency
d. Primary aldosteronism
e. Hereditary nephrogenic diabetes insipidus

3) A 38-year-old woman with three children below the age of seven is seen by Psychiatry. A diagnosis of bipolar disease with depression is made and medication is prescribed. Four months later, she returns and states that she now is thirsty and is voiding frequently (quantitated as approximately 3.5 liters a day). Serum sodium concentration ranges from 143-145 mEq/L and BUN is 22 mg/dl. The most likely agent/process responsible for the polyuria is:
a. Hypercalcemia
b. Lithium
c. Demeclocycline
d. Sickle cell disease
e. Prolonged low protein diet

4) A 76-year-old man is sent to the hospital from his nursing home because of obtundation, decreased skin turgor, fever and a blood pressure of 140/80 mmHg. The serum sodium concentration is 168 mEq/L (it was 142 mEq/L four months earlier). The most likely cause of the hypernatremia is:
a. Primary hypodipsia
b. Prolonged low protein diet
c. Hypercalcemia
d. Inadequate solute-free water replacement for cutaneous pure water loss
e. Lithium

5) The treatment goal for patient #4 is:
a. Reduce serum sodium concentration to normal in first 12 hours
b. Reduce serum sodium concentration to normal in 24 hours
c. Reduce serum sodium concentration to 150 mEq/L in 24 hours
d. Maintain serum sodium concentration at 165 mEq/L for first 8 hours
e. Reduce serum sodium concentration by 10 mEq/L in 24 hours


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