What is the treatment for a 14-year-old girl with severe vitamin D deficiency (hypovitaminosis D) and a vitamin D level of 6 ng/mL?

Treatment for 14-Year-Old Girl with Severe Vitamin D Deficiency (Level 6 ng/mL)

Start vitamin D3 (cholecalciferol) 50,000 IU once weekly for 8-12 weeks, then transition to maintenance therapy with 2,000 IU daily. 1, 2, 3

Understanding the Severity

• A vitamin D level of 6 ng/mL represents severe deficiency, placing this adolescent at significant risk for impaired bone mineralization, secondary hyperparathyroidism, and compromised skeletal development during a critical period of bone mass accrual. 2, 3, 4
• Severe deficiency is defined as levels below 10-12 ng/mL, which substantially increases risk for rickets and osteomalacia. 1
• The treatment goal is to achieve and maintain a 25(OH)D level of at least 30 ng/mL for optimal bone health and fracture prevention. 1, 2, 3

Loading Phase Protocol (Weeks 1-12)

• Administer vitamin D3 (cholecalciferol) 50,000 IU orally once weekly for 8-12 weeks. 1, 2, 3, 5
• Vitamin D3 is strongly preferred over vitamin D2 (ergocalciferol) because it maintains serum levels longer and has superior bioavailability, particularly important with weekly dosing intervals. 1, 2, 3
• This loading regimen delivers a cumulative dose of 400,000-600,000 IU over the treatment period, which is necessary to rapidly restore depleted vitamin D stores. 1

Essential Co-Interventions During Treatment

• Ensure adequate calcium intake of 1,000-1,300 mg daily from diet plus supplements if needed. 2, 3, 5
• Calcium is absolutely necessary for clinical response to vitamin D therapy—without adequate calcium, the vitamin D treatment cannot effectively improve bone health. 2, 3
• Good dietary calcium sources include milk, yogurt, cheese, fortified plant milks, and leafy greens. 3
• If dietary intake is insufficient, calcium supplements should be taken in divided doses of no more than 600 mg at once for optimal absorption. 1

Maintenance Phase (After Week 12)

• Transition to maintenance therapy with 2,000 IU of vitamin D3 daily. 1, 2, 3
• An alternative maintenance regimen is 50,000 IU monthly (equivalent to approximately 1,600 IU daily), though daily dosing is more physiologic for pediatric patients. 1, 2
• Continue maintenance therapy indefinitely to prevent recurrence of deficiency. 3, 5

Monitoring Protocol

• Recheck 25(OH)D levels at 3 months (after completing the loading phase) to confirm adequate response. 1, 2, 3
• The target level is at least 30 ng/mL, which provides optimal protection for bone health and reduces fracture risk. 1, 2, 3
• If levels remain below 30 ng/mL at 3 months, increase the maintenance dose by 1,000-2,000 IU daily. 1
• Using the rule of thumb: an intake of 1,000 IU vitamin D daily increases serum 25(OH)D by approximately 10 ng/mL, though individual responses vary. 1

Safety Considerations

• Daily doses up to 4,000 IU are considered completely safe for adolescents aged 9 years and older. 1, 2, 3, 6
• The upper safety limit for 25(OH)D is 100 ng/mL; levels above this should be avoided. 1, 2, 3
• Vitamin D toxicity is extremely rare and only occurs with prolonged intake of very high doses (typically over 10,000 IU daily for extended periods). 1, 3
• The prescribed weekly dose of 50,000 IU is well-established as safe with no significant adverse events reported in clinical trials. 1

Critical Pitfalls to Avoid

• Do not use active vitamin D analogs (calcitriol, alfacalcidol, doxercalciferol, paricalcitol) to treat nutritional vitamin D deficiency. 1, 2, 7
• These medications are reserved for specific conditions like chronic kidney disease with impaired 1α-hydroxylase activity and can cause hypercalcemia. 1
• Do not assume that lower daily doses (400-800 IU) will be sufficient for correction—these doses are for prevention in healthy individuals, not treatment of existing severe deficiency. 2, 4, 5
• Avoid single ultra-high loading doses (>300,000 IU) as they may be inefficient or potentially harmful. 1

Special Considerations for Adolescents

• This age represents a critical period for bone mass accrual, making adequate vitamin D status particularly important for long-term skeletal health and peak bone mass achievement. 2, 3, 4
• Dark-skinned adolescents, those with limited sun exposure, or those who are veiled may require ongoing higher maintenance doses due to reduced cutaneous vitamin D synthesis. 1, 2
• Encourage weight-bearing exercise (running, jumping, sports) for at least 30 minutes, 3 days per week to build strong bones during this critical developmental period. 3
• Adequate dietary sources of vitamin D (fatty fish, fortified milk, egg yolks) should be encouraged alongside supplementation. 2, 5, 8

Expected Outcomes

• With the prescribed regimen of 50,000 IU weekly for 12 weeks (total 600,000 IU), expect the 25(OH)D level to increase from 6 ng/mL to approximately 30-40 ng/mL. 1
• Clinical improvement in symptoms (if present), such as bone pain, muscle weakness, or fatigue, should occur within weeks of starting treatment. 5
• Long-term maintenance therapy will prevent recurrence and support optimal skeletal development through the remainder of adolescence. 3, 5