Vitamin%20d%20deficiency Treatment

Vitamin D

• Fat-soluble vitamin which acts as a hormone and steroid
• A prohormone synthesized in the skin after ultraviolet radiation exposure or absorbed from food sources
• Provides adequate levels of calcium and phosphorus via increased intestinal absorption
• Normal values: 20-100 ng/mL (50-250 nmol/L)
• Forms of vitamin D:
  
  • Ergocalciferol (Vitamin D₂)
    
    • Found in some plant foods and most vitamin D supplements
    • Formed upon exposure of ergosterol to irradiation
  • Cholecalciferol (Vitamin D₃)
    
    • Produced in sunlight exposed skin
    • Found in animal products
    • Formed when ultraviolet-B (UV-B) radiation converts 7-dehydrocholesterol in epidermal keratinocytes and dermal fibroblasts to pre-vitamin D which isomerizes to vitamin D₃
  • Calcidiol (25-hydroxyvitamin D or 25[OH]D)
    
    • Storage form of vitamin D
    • Formed in the liver after vitamin D bound to vitamin-D-binding protein (DBP)
    • Transported to the liver to undergo 25-hydroxylation to 25(OH)D
    • Major circulating form of vitamin D
    • Preferred monitoring indicator for vitamin D status due to its long circulating half-life of 2-3 weeks
  • Calcitriol (1,25-hydroxyvitamin D or 1,25[OH]₂D)
    
    • Active form of vitamin D
    • Formed in the kidney after 25(OH)D undergoes 1α-hydroxylation to form 1,25(OH)₂ vitamin D
    • Circulating half-life: Approximately 4 hours
    • Regulated by calcium, PTH and phosphate serum levels
    • Used in cases of acquired and inherited metabolic disorders of 25(OH)D and phosphate including chronic kidney disease, chronic granuloma-forming disorders, hereditary phosphate-losing disorders, oncogenic osteomalacia, pseudovitamin D-deficiency rickets and vitamin D-resistant rickets
    • Appears normal or elevated in cases of vitamin D deficiency due to secondary hyperparathyroidism

• Sources:
  
  • Skin exposure to sunlight
    
    • May require at least 3-5x longer exposure to make the same amount of vitamin D with naturally dark skin toned people
  • Food sources: Eggs, meat, mushrooms, oily fish (eg mackerel, salmon, sardines), cod liver oil and other fish oils
  • Fortified food sources: Milk, bread products, orange juices, cereals, yogurts and cheeses

• Suggested dietary intakes of vitamin D
  
  • Infants and children aged 0-1 year old: At least 400 IU/day; at least 1000 IU/day to maintain blood levels >30 ng/mL (75 nmol/L)
  • Children >1-18 year old and adults ≤70: At least 600 IU/day; at least 1500-2000 IU/day to maintain blood levels >30 ng/mL (75 nmol/L)
  • Adults aged >70 years old: At least 800 IU/day; at least 1500-2000 IU/day to maintain blood levels >30 ng/mL (75nmol/L)
  • Pregnancy and lactating women: At least 600 IU/day; at least 1500-2000 IU/day to maintain blood levels >30 ng/mL (75nmol/L)
  • Obese children and adults, children and adults on anticonvulsant medications, antifungals (eg Ketoconazole), antiretrovirals, and glucocorticoids: At least 2-3 times more than doses for their age group to achieve body’s vitamin D requirements

• Major functions:
  
  • Increases intestinal absorption of calcium and phosphorus
  • Prompts osteoclast maturation to resorb calcium from bones

Sunlight exposure

• Mild sunburn is equivalent to 10,000 to 25,000 IU dietary vitamin D
• Infants <6 months should be kept out of direct sunlight
• Full-body exposure in summer months for light pigmented skinned adults should be for 10-15 minutes to generate between 10,000-20,000 IU vitamin D₃ within 24 hours
• For individuals with darker pigmented skin 5-10 times more exposure will generate 10,000-20,000 IU vitamin D₃

Diet

• Rich in vitamin D sources (eg cod, mackerel and salmon)
• Fortified food products (eg diary products, orange juices)