Vitamin D deficiency: Difference between revisions

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==Background==
==Background==
*AKA: Hypovitaminosis D
*AKA: Hypovitaminosis D
*Vitamin D
*Vitamin D deficiency leads to impaired bone mineralization and diseases such as:
**Lipid soluble
**Acts as a hormone which:
***Stimulates intestinal calcium absorption
***Maintains adequate phosphate levels for bone development
***Regulates cell growth proliferation and apoptosis
***Modulates immune function and inflammation reduction
*Deficiency leads to impaired bone mineralization and disease such as:  
**[[Rickets]] in children
**[[Rickets]] in children
**[[Osteomalacia]] and [[Osteoporosis]] in adults
**[[Osteomalacia]] and [[osteoporosis]] in adults


==Metabolism and Physiology of Vitamin D==
===Metabolism and Physiology of Vitamin D===
*Vitamin D gained from diet, supplements, or sunlight exposure
*Gained from diet, supplements, or sunlight exposure
*Vitamin D undergoes hydroxylation in the liver producing 25-hydroxyvitamin D
**Fortified foods (mainstay, eg milk, cereals), supplements, fatty fish, egg yolks, fish liver oil, and some mushrooms
*A second hydroxylation occurs in the kidney producing 1,25-dihydroxyvitamin D which is the active form of vitamin D
**Synthesis of vitamin D occurs in the skin through exposure to ultraviolet B radiation from sunlight
**This step can occur extrarenally
*Hydroxylated in liver→ 25-hydroxyvitamin D, which is further hydroxylated in kidney or extrarenally→ 1,25-dihydroxyvitamin D (active form)
**Regulated by PTH, serum calcium, and phosphorus levels
**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==
===Etiology of Vitamin D Deficiency===
*Inadequate intake
*Inadequate dietary intake, inadequate sunlight exposure
**Dietary sources such as fortified foods and supplements are the mainstay of vitamin D intake
**Especially individuals with higher melanin content living in colder climates
**Foods rich in vitamin D include fatty fish, egg yolks, fish liver oil, and some mushrooms
*Impaired vitamin D absorption
*Inadequate sunlight exposure
**[[Crohn's disease]], [[cystic fibrosis]], pancreatic insufficiency
**Synthesis of vitamin D occurs in the skin through exposure to ultraviolet B radiation from sunlight
*Impairment in conversion of vitamin D into active metabolites
**Factors associated with vitamin D deficiency include darker skin pigmentation, prolonged winter season, and skin coverage
**[[Renal Failure]], [[Liver failure]]
*Disorders limiting vitamin D absorption
**[[Crohn's disease]]
**[[Cystic fibrosis]]
*Conditions preventing vitamin D conversion into active metabolites
**[[Renal Failure]]
**[[Liver failure]]


==Clinical Features==
==Clinical Features==
*Bone pain and muscle weakness
*Bone pain
*Muscle [[weakness]]
*Brittle bones
*Brittle bones
**[[Rickets]] in children
**[[Rickets]] in children
***Soft bones, skeletal deformities
***Soft bones, skeletal deformities
***Craniotabe: abnormal softening or thinning of the skull  
***Craniotabe: abnormal softening or thinning of the skull  
**[[Osteomalacia]] and [[Osteoporosis]] in adults leading to increased risk of fractures
**[[Osteomalacia]] and [[osteoporosis]] in adults leading to increased risk of fractures
*Associated with advancement of cancers
*Associated with advancement of cancers, particularly of breast, colon, ovarian, and prostate
**Breast, colon, ovarian, and prostate


==Differential Diagnosis==
==Differential Diagnosis==
*[[Hypocalcemia]]
*[[Hypocalcemia]]
*Hyperparathyroidism
*[[Hyperparathyroidism]]
*[[Hypophosphatemia]]
*[[Hypophosphatemia]]
*Malignancy
*Malignancy
*[[Nonaccidental trauma]]


==Evaluation==
==Evaluation==
*Diagnosed by measuring the concentration of 25-hydroxyvitamin D
*Assess for [[fractures]], if indicated
**This is the pre hormone, calcidiol, which is a precursor to the active form 1,25-dihydroxyvitamin D
*BMP, Mg/Phos, serum calcium
*Insufficient vitamin D defined as a 25-hydroxyvitamin level 25-75 nmol/L (normal range 75-250 nmol/L)
*Vitamin D assessed by measuring serum concentration of 25-hydroxyvitamin D (precursor to hormonally active 1,25-dihydroxyvitamin D)
*Vitamin D deficiency defined as a 25-hydroxyvitamin level <20-25 nmol/L
**Normal range: 75-250 nmol/L
*Screening adults not at risk and without symptoms not recommended
**Insufficiency: 25-75 nmol/L
**Deficiency: <25 nmol/L
**Screening adults not at risk and without symptoms not recommended


==Management==
==Management==
*Treat complications (e.g. [[fractures]], [[analgesia|pain]])
*Supplemental vitamin D
*Supplemental vitamin D
**Initial high-dosage treatment phase
**Initial high-dosage treatment phase: 1,000 IU cholecalciferol per 10 nmol/L required serum increase given daily for 2-3 months
***1,000 IU cholecalciferol per 10 nmol/L required serum increase given daily for 2-3 months
**Maintenance: 400 IU daily
**Followed by maintenance dosage
***Double dosage for premature infants, infants/children with dark pigmentation, children with limited sun exposure, and obese patients
***400 IU daily for all age groups
**Some populations may require higher dosing (i.e. parathyroid disease, chronic liver disease, renal failure, and malabsorption disorders)
***Double dosage for premature infants, dark pigmented infants/children, children with limited sun exposure, and obese patients
**Special populations may require higher dosing (i.e. parathyroid disease, chronic liver disease, renal failure, and malabsorption disorders


==See Also==
==See Also==
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*[[Hypocalcemia]]
*[[Hypocalcemia]]
*[[Hypophosphatemia]]
*[[Hypophosphatemia]]
{{template:vitamin deficiencies DDX}}


==External Links==
==External Links==
Line 74: Line 70:
==References==
==References==
<references/>
<references/>
*1. <Health Quality Ontario. Clinical utility of vitamin d testing: an evidence-based analysis. ''Ont Health Technol Assess Ser''. 2010;10(2): 1–93.>
#<Health Quality Ontario. Clinical utility of vitamin d testing: an evidence-based analysis. ''Ont Health Technol Assess Ser''. 2010;10(2): 1–93.>
*2. <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.>
#<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.>


[[Category:Misc/General]]
[[Category:FEN]]

Latest revision as of 19:20, 23 February 2021

Background

  • AKA: Hypovitaminosis D
  • Vitamin D deficiency leads to impaired bone mineralization and diseases such as:

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
  • 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
  • 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

Vitamin deficiencies

External Links

References

  1. <Health Quality Ontario. Clinical utility of vitamin d testing: an evidence-based analysis. Ont Health Technol Assess Ser. 2010;10(2): 1–93.>
  2. <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.>
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