Treatment for Vitamin D Level of 18 ng/mL
For a patient with a vitamin D level of 18 ng/mL, prescribe 50,000 units of vitamin D2 (ergocalciferol) or D3 (cholecalciferol) weekly for 8-12 weeks to correct the deficiency. 1, 2
Assessment and Classification
This vitamin D level of 18 ng/mL indicates vitamin D deficiency, which is defined as:
- Deficiency: <20 ng/mL (50 nmol/L)
- Insufficiency: 20-30 ng/mL (50-75 nmol/L)
- Optimal: >30 ng/mL (75 nmol/L)
Treatment Protocol
Initial Treatment Phase
- Dosage: 50,000 IU of vitamin D2 or D3 weekly
- Duration: 8-12 weeks
- Monitoring: Check 25(OH)D levels at the end of treatment period
This regimen is supported by multiple guidelines and is considered standard practice for correcting vitamin D deficiency 1, 2.
Special Considerations
- For patients with chronic kidney disease (GFR <30 ml/min/1.73 m²), guidelines specifically recommend vitamin D2 50,000 units orally every month for 6 months 2
- For patients with HIV infection, either D2 50,000 IU weekly for 8-12 weeks or D3 2,000 IU daily for 12 weeks is recommended 2
- For patients with obesity, malabsorption, or on medications affecting vitamin D metabolism, higher or more frequent dosing may be required 3
Maintenance Phase
After completing the initial treatment phase and normalizing vitamin D levels (>30 ng/mL), transition to a maintenance regimen:
- Standard maintenance: 800-1,000 IU of vitamin D3 daily 1, 4
- Higher-risk patients: 2,000-4,000 IU daily may be required 5
Monitoring
- Recheck 25(OH)D levels 3-4 months after initiating therapy 4
- If the patient has other conditions such as hyperparathyroidism or kidney disease, also monitor:
- Serum calcium and phosphorus: monthly for first 3 months, then every 3 months
- Parathyroid hormone (PTH): every 3 months 4
Important Clinical Pearls
- Vitamin D supplementation is generally very safe, with toxicity being rare even at doses up to 50,000-100,000 IU weekly 6, 7
- Ensure adequate calcium intake (1,000-1,500 mg daily) alongside vitamin D supplementation for optimal bone health 4
- The goal of treatment is to achieve 25(OH)D levels >30 ng/mL to reduce risk of fractures, falls, and other adverse health outcomes 1
- Research has shown that 2,000 IU daily as maintenance therapy may be insufficient to maintain levels above 30 ng/mL in some patients, particularly those with obesity or malabsorption 5
This treatment approach is designed to safely and effectively correct vitamin D deficiency while minimizing the risk of adverse effects and optimizing long-term health outcomes.