Diagnostic Procedure

The Task Force recommends screening for vitamin D deficiency using the serum circulating 25-hydroxyvitamin D [25(OH)D] level, measured by a reliable assay in individuals who are at risk for vitamin D deficiency. Population screening for individuals who are not at risk is not recommended. Vitamin D deficiency is defined as a 25(OH)D level below 20 ng/ml (50 nmol/L). Vitamin D insufficiency is defined as a 25(OH)D level of 21–25 ng/ml (>5 nmol/L). The Task Force recommended against using the serum 1,25(OH)₂D assay to screen for deficiency. Rather, it should only be used to monitor certain conditions, such as acquired and inherited vitamin D and phosphate metabolism disorders.

Recommended Dietary Intakes for Patients at Risk for Vitamin D Deficiency

Maintenance Tolerable Upper Limits

Maintenance tolerable upper limits (UL) of vitamin D are not to be exceeded without medical supervision. These should be 1000 IU/day for infants aged up to 6 months; 1500 IU/day for infants aged from 6 months to 1 year; at least 2500 IU/day for children aged 1 to 3 years; 3000 IU/day for children aged 4 to 8 years; and 4000 IU/day for everyone aged >8 years. Higher levels of 2000 IU/day for children aged 0 to 1 year, 4000 IU/day for children aged 1 to 18 years, and 10,000 IU/day for children and adults aged ≥19 years might be needed to correct vitamin D deficiency.

Treatment and Prevention Strategies for Those Who Are Vitamin D-Deficient

Either vitamin D₂ or vitamin D₃ should be used for the treatment and prevention of vitamin D deficiency.

• Infants and toddlers (0 to 1 year) who are vitamin D-deficient should be treated with 2000 IU/day of vitamin D₂ or vitamin D₃ or with 50,000 IU of vitamin D₂ or vitamin D₃ once weekly for 6 weeks to achieve a blood level of 25(OH)D above 30 ng/ml; maintenance therapy should be 400–1000 IU/day

• Children aged 1 to 18 years who are vitamin D-deficient should be treated with 2000 IU/day of vitamin D₂ or vitamin D₃ for at least 6 weeks or with 50,000 IU of vitamin D₂ once a week for at least 6 weeks to achieve a blood level of 25(OH)D above 30 ng/ml, followed by maintenance therapy of 600 to 1000 IU/day

• All adults who are vitamin D-deficient should be treated with 50,000 IU of vitamin D₂ or vitamin D₃ once a week for 8 weeks or the equivalent of 6000 IU of vitamin D₂ or vitamin D₃ daily to achieve a blood level of 25(OH)D above 30 ng/ml, followed by maintenance therapy of 1500–2000 IU/day

• Patients who are obese, have malabsorption syndromes, and those on medications affecting vitamin D metabolism should receive a higher dose (2 to 3 times higher; ie, at least 6000 to 10,000 IU/day) of vitamin D₂ or vitamin D₃ to treat deficiency and maintain a 25(OH)D level above 30 ng/ml; maintenance therapy should be 3000 to 6000 IU/day

• Patients with extrarenal production of 1,25(OH)2D should receive serial monitoring of 25(OH)D levels and serum calcium levels during treatment with vitamin D to prevent hypercalcemia

• Patients with primary hyperparathyroidism and vitamin D deficiency should receive treatment with vitamin D as needed; serum calcium levels should be monitored

Noncalcemic Benefits of Vitamin D

The Task Force recommended prescribing vitamin D supplementation for fall prevention. It did not recommend vitamin D supplementation beyond recommended daily needs for the purpose of preventing cardiovascular disease or death or improving quality-of-life (Table 1).

The major source of vitamin D for adults and children is unprotected sun exposure; without it, it is difficult, if not impossible, to obtain an adequate amount of vitamin D from dietary sources without supplementation. Concerns about melanoma and other types of skin cancer make it necessary to avoid excessive exposure to midday sun. Such worries strengthen the case for supplementation, especially among those who live at about 33° latitude [Grant WB et al. Prog Biophys Mol Biol 2009].