A 64 year old man with multiple myeloma has been vomiting since the past 2days. Laboratory investigations: Ca2+=3.2mmol/l, K+=5mmol/l, Na+=149mmol/l and PCV=55%. What is the most appropriate next step?

The key is C. IV fluids. [Multiple myeloma itself is a cause of vomiting and also associated hypercalcemia can cause sickness. As the patient is vomiting for 2 days there may be considerable dehydration and also the hypercalcemia needs treatment with IV fluid].