Outpatient / Endocrinology

Vitamin D Deficiency

Last Updated: 5/5/2023

# Vitamin D Deficiency

History: *** (osteoporosis, falls, 

Etiology: *** (hyperPTH, lack of sunlight, alcohol, malabsorption from IBD, celiac, gastrectomy, impaired synthesis from CKD or ESLD, drugs (steroids, AED both increase metabolism of VitD)


  • f/u Calcium, PTH, CMP, Phos
  • 25(OH)D <12 - load 50,000 U cholecalciferol weekly for 8 weeks, then 800-1000 units daily
  • 25(OH)D 12-20 - 1000-2000 units cholecalciferol daily
  • 25(OH)D 20-30 - 600-800 units cholecalciferol daily
  • f/u repeat level in 3-4 months

Template coming soon!

Patient Guidance and Information

New Diagnosis of Vitamin D Deficiency

Based on your recent lab results, you have been diagnosed with a vitamin D deficiency. Vitamin D is essential for maintaining healthy bones and supporting your immune system. Your body naturally produces vitamin D when exposed to sunlight, but it can also be obtained through certain foods and supplements.

I recommend taking a vitamin D supplement called ***. Please take *** with food. We can plan to follow up your Vitamin D levels in 3-4 months.

Additionally, consider spending more time outdoors in sunlight and incorporating vitamin D-rich foods, such as fatty fish and dairy products, into your diet.

If You Remember Nothing Else

Vitamin D should be supplemented when 25(OH)D (calcidiol - the strorage form) is less than 20-30. You should supplement with D3 (cholecalciferol) instead of D2 (ergocalciferol).

Clinical Pearls

  • No regular screening - send if fractures, calcium disorders, hyperPTH
  • Send 25(OH)D - calcidiol (storage form, long half-life)
  • Vitamin D - 25(OH)D is calcidiol which is the storage form  used to assess for insufficiency; 1,25(OH)D is the active form
  • Vitamin D2 (ergocalciferol) comes from plant sources; D3 (cholecalciferol) is formed in skin and comes from animal sources and is more effective at raising levels when supplemented and is thus preferred; difference is at the level of liver metabolism
  • It is very hard to get Vitamin D from diet so if you can’t get from sun will have to supplement
  • It is very hard to get too much Vitamin D to the point of toxicity - pretty much always okay to supplement
  • Liver hydroxylates calecalciefrol (D3) to calcidiol which is again hydroxylated in kidney to active form of 1,25(OH)D
  • Higher likelihood of VitD deficiency in those with heavily pigmented skin - more UV absorbed by melanin, lower rates of VitD synthesis
  • Breastmilk is low in VitD, so infants <1 exclusively breast fed should be supplemented
  • Breastmilk is low in VitD, so infants <1 exclusively breast fed should be supplemented
  • Cholecalciferol (D3) synthesized in stratum basale when exposed to UV light
  • 1-alpha hydroxylase in kidney is regulated by calcium, phosphate, PTH levels
  • Vitamin D leads to increased absorption of calcium and phosphate in intestines and stimulates bone mineralization

Trials and Literature

  • Review of Vitamin D Deficiency in NEJM

Other Resources