Which electrolyte disturbance presents with polydipsia, irritability, tremulousness, ataxia, and lethargy?

Which electrolyte disturbance presents with polydipsia, irritability, tremulousness, ataxia, and lethargy?

• A. Hyponatremia
• B. Hypernatremia
• C. Hypokalemia
• D. Hypocalcemia

Answer: (B)

Hypernatremia best explains this presentation. When serum sodium is elevated, plasma osmolality rises, pulling water out of brain cells. The brain responds with neurologic signs due to cellular dehydration—irritability, tremulousness, ataxia, and lethargy—along with polydipsia as the body tries to replace the free water deficit. Hyponatremia would more commonly cause confusion or seizures from cerebral edema; hypokalemia brings weakness and cramps; hypocalcemia causes tingling, tetany, and different neuromuscular irritability. The pattern here—the thirst with prominent dehydration and neurobehavioral symptoms—points to high sodium and high osmolality.

Hypernatremia best explains this presentation. When serum sodium is elevated, plasma osmolality rises, pulling water out of brain cells. The brain responds with neurologic signs due to cellular dehydration—irritability, tremulousness, ataxia, and lethargy—along with polydipsia as the body tries to replace the free water deficit. Hyponatremia would more commonly cause confusion or seizures from cerebral edema; hypokalemia brings weakness and cramps; hypocalcemia causes tingling, tetany, and different neuromuscular irritability. The pattern here—the thirst with prominent dehydration and neurobehavioral symptoms—points to high sodium and high osmolality.