Dosing Guidelines for Vitamin D Deficiency

• The preferred test for Vitamin D deficiency is a serum 25-hydroxy Vitamin D level:
• In the past, the lower limit of normal for most 25-OH Vitamin D assays was 8-10 ng/ml
• <20 ng/ml- Vitamin D deficiency; treatment is strongly recommended
• 20-30 ng/ml- Vitamin D insufficiency, treatment is recommended
• >30 to 100 ng/ml-optimum Vitamin D level
• >100 ng/ml-high Vitamin D level, treatment should be adjusted downward


• Biochemical picture of advanced (severe) Vitamin D deficiency:
• Low serum calcium (especially ionized calcium)
• Low phosphorus
• Elevated PTH
• Low urinary calcium
• Elevated alkaline phosphatase


• Risk factors for Vitamin D deficiency:
• Increasing age
• Chronic steroid use
• Chronic anticonvulsant drug use
• Malabsorption syndromes (including particularly Celiac Disease)
• Little sun exposure (including institutionalized patients)
• Chronic low intake of calcium (low dairy product intake; especially patients with lactose intolerance)


• Clinical situations where Vitamin D deficiency should be considered:
• Anyone found to have reduced BMD (Osteopenia OR Osteoporosis)
• Hx of risk factors for Vitamin D deficiency
• Hx of an elevated PTH level with normal or low calcium
• Hx of elevated alkaline phosphatase level


• Suggested treatment of Vitamin D deficiency
• Vitamin D deficiency (25-OH Vitamin D level <20): Vitamin D 50,000 units twice a week for 3 months, repeat 25-OH Vitamin D level
• If >20 ng/ml, change the Vitamin D supplement to 50,000 units once a week
• If still <20 ng/ml, continue Vitamin D 50,000 units twice a week OR consider giving it more frequently (with certain clinical situations, especially with malabsorption syndromes, up to 50,000 units daily may be needed)
• Vitamin D insufficiency (25-OH Vitamin D level 20-30 ng/ml):Vitamin D 50,000 units once a week for 3 months, repeat 25 OH Vitamin D level
• If <30 ng/ml, continue Vitamin D 50,000 units once a week
• If >30 ng/ml, change to Vitamin D as part of a calcium supplement and/or as multiple vitamin (give at least 800 IU/day)


• NOTE: Treatment for Vitamin D deficiency should ALWAYS include a calcium supplement (possible exception: a patient with a history of kidney stones)