VetOne Cyanocobalamin Vitamin B 12 Sterile Solution, 1,000 mcg mL, 100 mL 100 mL Vitamin B 12 Injection, 1,000 mcg mL Giving vitamin B12 parenterally? Which electrolyte should you check first? Answer: Potassium. And why does it matter? Because rapid correction of severe B12 deficiency can trigger a surge in Vitamin B12, Cyanocobalamin, Injection, 1000mcg mL, 1mL Vial, 25 Vials Med Vet International Cyanocobalamin (B12) Injection 1000 mcg mL, Multiple Dose Vial 30 mL McGuff