Vitamin D deficiency: Difference between revisions
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*Vitamin D deficiency leads to impaired bone mineralization and diseases such as: | *Vitamin D deficiency leads to impaired bone mineralization and diseases such as: | ||
**[[Rickets]] in children | **[[Rickets]] in children | ||
**[[Osteomalacia]] and [[ | **[[Osteomalacia]] and [[osteoporosis]] in adults | ||
===Metabolism and Physiology of Vitamin D=== | ===Metabolism and Physiology of Vitamin D=== | ||
*Gained from diet, supplements, or sunlight exposure | *Gained from diet, supplements, or sunlight exposure | ||
**Fortified foods (mainstay), supplements, fatty fish, egg yolks, fish liver oil, and some mushrooms | **Fortified foods (mainstay, eg milk, cereals), supplements, fatty fish, egg yolks, fish liver oil, and some mushrooms | ||
**Synthesis of vitamin D occurs in the skin through exposure to ultraviolet B radiation from sunlight | **Synthesis of vitamin D occurs in the skin through exposure to ultraviolet B radiation from sunlight | ||
*Hydroxylated in liver→ 25-hydroxyvitamin D, which is further hydroxylated in kidney or extrarenally→ 1,25-dihydroxyvitamin D (active form) | *Hydroxylated in liver→ 25-hydroxyvitamin D, which is further hydroxylated in kidney or extrarenally→ 1,25-dihydroxyvitamin D (active form) | ||
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**Regulate cell growth proliferation and apoptosis | **Regulate cell growth proliferation and apoptosis | ||
**Modulate immune function and inflammation reduction | **Modulate immune function and inflammation reduction | ||
===Etiology of Vitamin D Deficiency=== | ===Etiology of Vitamin D Deficiency=== | ||
*Inadequate dietary intake, inadequate sunlight exposure | *Inadequate dietary intake, inadequate sunlight exposure | ||
**Especially individuals with higher melanin content living in colder climates | |||
*Impaired vitamin D absorption | *Impaired vitamin D absorption | ||
**[[Crohn's disease]], [[cystic fibrosis]] | **[[Crohn's disease]], [[cystic fibrosis]], pancreatic insufficiency | ||
*Impairment in conversion of vitamin D into active metabolites | *Impairment in conversion of vitamin D into active metabolites | ||
**[[Renal Failure]], [[Liver failure]] | **[[Renal Failure]], [[Liver failure]] | ||
Revision as of 19:18, 23 February 2021
Background
- AKA: Hypovitaminosis D
- Vitamin D deficiency leads to impaired bone mineralization and diseases such as:
- Rickets in children
- Osteomalacia and osteoporosis in adults
Metabolism and Physiology of Vitamin D
- Gained from diet, supplements, or sunlight exposure
- Fortified foods (mainstay, eg milk, cereals), supplements, fatty fish, egg yolks, fish liver oil, and some mushrooms
- Synthesis of vitamin D occurs in the skin through exposure to ultraviolet B radiation from sunlight
- Hydroxylated in liver→ 25-hydroxyvitamin D, which is further hydroxylated in kidney or extrarenally→ 1,25-dihydroxyvitamin D (active form)
- Second hydroxylation regulated by PTH, serum calcium, and phosphorus levels
- Vitamin D acts to:
- Stimulate intestinal calcium absorption
- Maintain adequate phosphate levels for bone development
- Regulate cell growth proliferation and apoptosis
- Modulate immune function and inflammation reduction
Etiology of Vitamin D Deficiency
- Inadequate dietary intake, inadequate sunlight exposure
- Especially individuals with higher melanin content living in colder climates
- Impaired vitamin D absorption
- Crohn's disease, cystic fibrosis, pancreatic insufficiency
- Impairment in conversion of vitamin D into active metabolites
Clinical Features
- Bone pain
- Muscle weakness
- Brittle bones
- Rickets in children
- Soft bones, skeletal deformities
- Craniotabe: abnormal softening or thinning of the skull
- Osteomalacia and Osteoporosis in adults leading to increased risk of fractures
- Rickets in children
- Associated with advancement of cancers, particularly of breast, colon, ovarian, and prostate
Differential Diagnosis
Evaluation
- Assess for fractures, if indicated
- BMP, Mg/Phos, serum calcium
- Vitamin D assessed by measuring serum concentration of 25-hydroxyvitamin D (precursor to hormonally active 1,25-dihydroxyvitamin D)
- Normal range: 75-250 nmol/L
- Insufficiency: 25-75 nmol/L
- Deficiency: <25 nmol/L
- Screening adults not at risk and without symptoms not recommended
Management
- Treat complications (e.g. fractures, pain)
- Supplemental vitamin D
- Initial high-dosage treatment phase: 1,000 IU cholecalciferol per 10 nmol/L required serum increase given daily for 2-3 months
- Maintenance: 400 IU daily
- Double dosage for premature infants, infants/children with dark pigmentation, children with limited sun exposure, and obese patients
- Some populations may require higher dosing (i.e. parathyroid disease, chronic liver disease, renal failure, and malabsorption disorders)
See Also
External Links
References
- <Health Quality Ontario. Clinical utility of vitamin d testing: an evidence-based analysis. Ont Health Technol Assess Ser. 2010;10(2): 1–93.>
- <Holick MF, Binkley NC, Bischoff-Ferrari HA, Gordon CM, Hanley DA, Heaney RP, Murad H, and Weaver CM. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society Clinical Practice Guideline. "J Clin Endocrinol Metab". Jul 2011; 96(7): 1911–1930.>