Serum calcium should be measured often (weekly at first, then monthly) in all patients receiving large doses of vitamin D, particularly the potent 1, 25-dihydroxyvitamin D Treatment of Vitamin D Toxicity IV hydration plus corticosteroids or bisphosphonates After stopping vitamin D intake, hydration (with IV normal saline) and corticosteroids or bisphosphonates (which inhibit bone resorption) are used to reduce blood calcium levels.