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
Immediate antagonism of the cardiac effects of hyperkalemia is done by 
Select and explain. 
A. IV Calcium, B. Dextroversion, C. Dialysis, D. Glucose + Insulin
A: IV Calcium
Answer: A: IV Calcium 
Explanation: Intravenous calcium serves to protect the hea. Calcium raises the action potential threshold and reduces excitability, without changing the resting membrane potential. By restoring the difference between resting and threshold potentials, calcium reverses the depolarization blockade due to hyperkalemia. The recommended dose is 10 mL of 10% calcium gluconate (3-4 mL of calcium chloride), infused intravenously over 2-3 min with cardiac monitoring. Ref: Harrison 19e pg: 312