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
A 9 year old girl was admited for dialysis. On laboratory examination her potassium levels were 7.8 mEq/L. Which of the following would quickly lower her increased potassium levels- 
Select and explain. 
A. IV calcium gluconate, B. IV Glucose and insulin, C. Oral kayexalate in sorbitol, D. IV NaHCO3
B: IV Glucose and insulin
Answer: B: IV Glucose and insulin 
Explanation: Insulin lowers plasma K+ concentration by shifting K+ into cells. The recommended dose is 10 units of intravenous regular insulin followed immediately by 50 mL of 50% dextrose (D50W, 25 g of glucose total); the effect begins in 10-20 min, peaks at 30-60 min, and lasts for 4-6 h. (ref: harrisons. 19E pg 312)