Vitamin D in Primary Care

Sources; UpToDate, Audio Digest
Vitamin D is a Fat soluble vitamin with its main role = helps regulate calcium and parathyroid levels and plays a role in immune system and muscle function.
Vitamin D2 (ergocalciferol)= main form circulating with 1/2 life of 2 to 3 weeks
Vitamin D3  ( cholecalciferol) = regulates absorption of Calcium and phosphorus in the intestines
How is it Made?
  1. dermal synthesis by the SUN – uVB
  2. processed in the Liver
  3. functional form activated in Kidney
Other sources
  1. Food -> oily fish, liver, egg yolks
  2. Nutritional supplements
Normal levels of vitamin D (differ by agency) 30 ng/ml is typically agreed upon but some say 20ng/ml
Reasons for deficiency
  1. low intake/sun exposure/ malabsorption
  2. liver disease
  3. kidney disease
  4. end organ sensitivity
Risk factors
  1. darker skin
  2. use of sunscreen ( 30spf blocks 90%)
  3. decrease sun exposure/winter
    1. latitudes greater than 40
    2. whites need 10-15 min between 10 -3
    3. blacks need about 6 to 10 x more than whites
    4. Asian/Indian need about 3 times more than whites
  4. vegetarians
  5. chronic glucocorticoid use
  6. Absorption issues (celiac, IBD, CF, bariatric surgery)
  7. Obesity = stores vitamin D levels in fat
When to supplement with Vitamin D3 -> goals should be 25ng/ml -> recheck in 3 to 4 months
  1. Breastfed infants – 400 IU/daily
  2. History of vitamin D deficiency
  3. low dietary intake
  4. dark skin
Dosing
  1. Infants (breastfed) = 400 IU/daily
  2. 1 – 70  years = 600 IU/daily
  3. >70 = 800 IU/daily
  4. For pregnant and lactating women routinely 400 to 600mg IU/daily
Another approach is dosing by deficiency level
  1. Severe deficiency <10 = 50,000 IU weekly for 8 weeks, then 800IU/daily
  2. 10- 20 = 800 – 1000 IU/daily
  3. 20-30 = 600-800 IU/daily
For postmenopausal women Vit. D may be beneficial if given with Calcium 1200mg in reducing risk of fracture
Screening = lacks evidence if asymptomatic w/ no risk factors. If risk factors can screen.
Lab = Vitamin D, 25 Hydroxy is lab for screening ( total 25(OH)D concentration )
Deficiency can lead to rickets (children) and osteomalacia (adults) at severe levels. Other symptoms can include bone pains/fractures, muscles weakness and difficulty walking.