Overview
Vitamin D3 (cholecalciferol) is a fat-soluble vitamin essential for calcium absorption and bone mineralization. It is commonly used to treat and prevent vitamin D deficiency, which can lead to conditions like osteoporosis and rickets. Supplementation helps maintain adequate serum 25-hydroxyvitamin D levels for optimal bone health.
Mechanism of Action
Vitamin D3 is converted in the liver to 25-hydroxyvitamin D and then in the kidneys to its active form, 1,25-dihydroxyvitamin D. This active metabolite increases intestinal absorption of calcium and phosphate, promotes bone mineralization, and regulates parathyroid hormone secretion.
Indications
- Treatment and prevention of vitamin D deficiency
- Management of osteoporosis (as adjunct therapy)
- Prevention and treatment of rickets in children
- Hypoparathyroidism management
- Renal osteodystrophy in chronic kidney disease
Common Doses
- 400 IU
- 800 IU
- 1000 IU
- 2000 IU
- 5000 IU
- 50,000 IU (prescription strength)
Dosage
Typical adult maintenance dose is 600-800 IU daily; higher doses (1,000-4,000 IU daily) may be used for deficiency treatment. Dosage should be individualized based on serum 25-hydroxyvitamin D levels, age, and clinical condition.
Contraindications
- Hypercalcemia
- Vitamin D toxicity
- Hypersensitivity to cholecalciferol or any product components
Side Effects
- Hypercalcemia (symptoms: nausea, vomiting, constipation, weakness)
- Hypercalciuria
- Renal impairment with prolonged excessive use
- Rare allergic reactions
Interactions
- Thiazide diuretics: increased risk of hypercalcemia
- Corticosteroids: may reduce vitamin D effectiveness
- Anticonvulsants (phenytoin, phenobarbital): may increase vitamin D metabolism
- Orlistat: may reduce vitamin D absorption
- Cholestyramine: may decrease absorption
Counseling Points
- Take with food containing fat for optimal absorption
- Do not exceed recommended dosage without medical supervision
- Regular sunlight exposure contributes to vitamin D synthesis
- Inform healthcare provider of all medications and supplements
- Report symptoms of hypercalcemia (nausea, vomiting, excessive thirst)