vitamin%20d%20deficiency
VITAMIN D DEFICIENCY

Vitamin D deficiency is a condition wherein there is low circulating levels of vitamin D. Vitamin D is an essential steroid hormone found in the body.

It results from inadequate sunlight exposure, malabsorptions &/or inadequate nutrition.

Vitamin D insufficiency is a less severe state of calcidiol deficiency and associated w/ parathyroid hormones and osteoporosis.

 

Pharmacotherapy

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

Non-Pharmacological Therapy

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)
Digital Edition
Asia's trusted medical magazine for healthcare professionals. Get your MIMS Endocrinology - Malaysia digital copy today!
Sign In To Download
Editor's Recommendations
Most Read Articles
Pearl Toh, 6 days ago
Every-two-month injections of the long-acting cabotegravir + rilpivirine were noninferior to once-monthly injections for virologic suppression at 48 weeks in people living with HIV*, according to the ATLAS-2M** study presented at CROI 2020 — thus providing a potential option with more convenient dosing.
Stephen Padilla, 19 Mar 2020
The assumption that children are less vulnerable to the coronavirus disease 2019 (COVID-19) compared to adults is not quite true and may even be dangerous, suggests a recent study.
22 Mar 2020
Sustained use of lopinavir-combined regimen appears to confer benefits among patients with the novel coronavirus disease (COVID-19), with improvement possibly indicated by increasing eosinophils, suggests a recent study.
24 Mar 2020
COVID-19 is a novel disease, with no existing immunity. The virus can be transmitted from person to person, quickly and exponentially. Here’s what we can do to slow down the spread, if not contain the outbreak.