We need you! Join our contributor community and become a WikEM editor through our open and transparent promotion process.
Vitamin D deficiency
From WikEM
Contents
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), 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
- 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
- Rickets in children
- Associated with advancement of cancers, particularly of breast, colon, ovarian, and prostate
Differential Diagnosis
- Hypocalcemia
- Hyperparathyroidism
- Hypophosphatemia
- Malignancy
- Nonaccidental trauma
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.>
