Can vitamin D2 (ergocalciferol) be given to a patient with a solitary kidney (single kidney)?

Vitamin D2 (Ergocalciferol) in Patients with a Single Kidney

Yes, vitamin D2 (ergocalciferol) can be safely administered to patients with a solitary kidney, but vitamin D3 (cholecalciferol) is generally preferred due to its higher bioefficacy. 1, 2

Rationale for Vitamin D Supplementation in Kidney Disease

• Vitamin D insufficiency is highly prevalent (80-90%) in patients with chronic kidney disease (CKD) 1
• Even with a single kidney, maintaining adequate vitamin D levels is important for:
  • Preventing secondary hyperparathyroidism
  • Reducing risk of bone demineralization
  • Supporting extrarenal calcitriol synthesis 1

Vitamin D2 vs. D3 Considerations

• Cholecalciferol (D3) has higher bioefficacy than ergocalciferol (D2), though long-term comparative trials in humans are limited 1, 2
• Research shows vitamin D3 is more effective than D2 in hemodialysis patients:
  • D3 achieved 25(OH)D levels >30 ng/mL in 84% of patients compared to only 15-27% with D2 3
• If using D2, higher doses may be required as one unit of D3 is equivalent to approximately 4 units of D2 4

Dosing Recommendations

For patients with a single kidney (assuming some degree of CKD):

• For vitamin D deficiency/insufficiency treatment:

  • Severe deficiency (<5 ng/mL): 50,000 IU weekly for 8-12 weeks 1, 2
  • Mild deficiency (5-15 ng/mL): 8,000 IU daily for 4 weeks, then 4,000 IU daily for 2 months 1
  • Insufficiency (16-30 ng/mL): 4,000 IU daily for 12 weeks or 50,000 IU every other week for 12 weeks 1, 2

• For maintenance therapy:

  • 2,000 IU daily or 50,000 IU every 4 weeks 1, 2

Monitoring Recommendations

• Check serum 25(OH)D levels after 3-6 months of supplementation 2
• Monitor serum calcium and phosphorus levels regularly 1, 2
• Target 25(OH)D level: ≥30 ng/mL (75 nmol/L) 2
• Annual monitoring of 25(OH)D levels is recommended, preferably at the end of darker months 2

Important Considerations and Cautions

• Patients with CKD may require higher doses due to resistance to vitamin D replacement therapy 5
• Avoid using calcitriol, alfacalcidol, or other synthetic active vitamin D analogs to treat 25(OH)D deficiency 1, 2
• Watch for signs of vitamin D toxicity (hypercalcemia, hypercalciuria) 2
• Short-term treatment with high-dose ergocalciferol has not shown harmful effects on markers of mineral homeostasis in CKD patients 6

Clinical Pearls

• The presence of CKD and diabetes mellitus is associated with resistance to correction of vitamin D deficiency 5
• Ensure adequate calcium intake (1,000-1,200 mg daily) alongside vitamin D supplementation 2
• Vitamin D supplementation may be particularly important in patients with a single kidney to help maintain bone health and mineral homeostasis 1, 7