This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fluid and electrolytes, Subject name: Medicine
Acute hyponatremia becomes symptomatic at 
Select and explain. 
A. <135 mEq, B. <125 mEq, C. <120 mEq, D. <115 mEq
B: <125 mEq
Answer: B: <125 mEq 
Explanation: Severe symptoms (e.g., coma, seizures) typically occur when the sodium level falls below 120 mEq per L, but can occur at less than 125 mEq per L. Severe symptomatic hyponatremia must be corrected promptly because it can lead to cerebral edema, irreversible neurologic damage, respiratory arrest, brainstem herniation, Ref Davidson 23rd edition pg 350