What is Vitamin D?
Vitamin D is a fat-soluble vitamin that our body makes when the skin is exposed to sunlight. It is also found in certain foods like fish, dairy, and eggs. Vitamin D helps the body maintain strong bones, reduces fracture risk, supports muscle function, and is beneficial for immune function and overall health. In this article, we will share tips on vitamin D dosing and monitoring.
Dosing and Osteoporosis
AACE guidelines and NOGG guidelines recommend that everyone with osteoporosis should maintain adequate vitamin D levels. Taking Vitamin D 1000 – 2000 IU daily helps to maintain vitamin D level above 30 ng/mL in the body. Vitamin D does not replace osteoporosis medication, but it makes them more effective.
What About Fall Prevention?
Low vitamin D can cause muscle weakness, which can increase the fall risk in older people. Studies show that taking 700 – 800 IU daily reduces the fall and fracture risk in seniors. A 700 IU dosage form is not common, and so it is not routinely used in practice.
Vitamin D Deficiency – Monitoring Levels and Dosing
Vitamin D deficiency happens when the body does not have enough vitamin D. Providers usually measure this with a blood test called 25-hydroxyvitamin D [25(OH)D] Test. When vitamin D is low, your body has a reduced capacity to absorb calcium. Bone becomes weak, leading to osteoporosis, fractures, and an increased risk of falls.
| Deficiency | < 20 ng/mL (50 nmol/L) |
| Insufficiency | 20 – 30 ng/mL (50 – 70 nmol/L) |
| Sufficiency | 30 – 50 ng/mL (75-125 nmol/L) |
If your blood test shows a deficiency (<20 ng/mL), treatment often starts with ergocalciferol (D2) 50,000 IU weekly for 8 weeks. After high-dose therapy, initiate vitamin D3 1000 – 2000 IU daily for maintenance therapy. The most common and readily available dosage forms are 400, 800, and 1,000 units.
| Indication | Dose | |
| Osteoporosis | Vit D3 1000 – 2000 IU daily | |
| Fall Prevention | Vit D3 700 – 800 IU daily | |
| Vitamin Deficiency | If deficient (<20 ng/mL), Ergocalciferol (D2) 50,000 IU weekly for 8 weeks → Vit D3 800 – 1000 IU daily | Check the level every 3 months |
| If insufficient (20 – 30 ng/mL), Vit D3 1000 – 2000 IU daily |
This article was written by Jeongmin Lee, PharmD Candidate in collaboration with Eric Christianson, PharmD, BCPS, BCGP
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References
American Association of Clinical Endocrinologists, & American College of Endocrinology. (2020). Clinical practice guidelines for the diagnosis and treatment of postmenopausal osteoporosis—2020 update. Endocrine Practice, 26(Suppl 1), 1–44. https://doi.org/10.4158/GL-2020-0524SUPPL
National Osteoporosis Guideline Group (NOGG). (2024). Clinical guideline for the prevention and treatment of osteoporosis (Updated December 2024). Retrieved from https://www.nogg.org.uk
Płudowski, P., Kos-Kudła, B., Walczak, M., Fal, A., Zozulińska-Ziółkiewicz, D., Sieroszewski, P., Peregud-Pogorzelski, J., Lauterbach, R., Targowski, T., Lewiński, A., Spaczyński, R., Wielgoś, M., Pinkas, J., Jackowska, T., Helwich, E., Mazur, A., Ruchała, M., Zygmunt, A., Szalecki, M., … Misiorowski, W. (2023). Guidelines for preventing and treating vitamin D deficiency: A 2023 update in Poland. Nutrients, 15(3), 695. https://doi.org/10.3390/nu15030695
American Academy of Family Physicians (AAFP). (2009). Recognition and management of vitamin D deficiency. American Family Physician, 80(8), 841–846. Retrieved from https://www.aafp.org
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