Vitamin D Supplementation

Jordan Dimmerling, Pharm D Candidate, Ohio Northern University

 
Vitamin D supplementation has become commonplace among adults, with increasing popularity among elderly individuals for a multitude of reasons. It has been shown to not only have positive benefits in osteoporosis prevention and treatment by aiding calcium absorption and improving balance, but is also linked with improved muscle strength and CV function, lowered cancer risk (breast, colon, and prostate), and positive effects on immune-oriented diseases (MS, T1DM, and RA). The seemingly endless availability of vitamin D to consumers also makes it convenient to supplement. It can be found in different strengths allowing for a wide range of dosing frequencies, from multiple times daily to once monthly, OTC or Rx only, and alone, or in multi-vitamin formulations.
Screening for low levels of vitamin D should only occur in those patients who are at risk or have a compelling medical history such as: persistent musculoskeletal pain, osteoporosis, Rheumatoid arthritis, malabsorption syndromes, CV disease, elderly (patients >71 years old), persons with dark skin, chronic corticosteroid use, history of insufficient sun exposure, lack of vitamin D in the diet and only possibly if the patient has a positive history of: obesity, T2DM, CKD, hyperparathyroidism, and depression. Once the at-risk patient has been identified, the preferred test is the serum 25-hydroxyvitamin D (25OHD) assay. Acceptable levels would be greater than 30 ng/mL, an insufficiency would be in the 21-29 ng/mL range, and a deficiency would be a value of less than 20 ng/mL. Testing of the 25 (OH) levels should only be preformed every 3 months; this is due to vitamin D having a half life of almost 1 month and a new steady state being reached in approximately 3 months.
Recommended intake of vitamin D for the high-risk elderly population is anywhere from 800-1000 IU daily, which is enough to see benefits in bone and muscle, but could be as much as 1500-2000 IU daily. This amount is known as the maintenance dose, but it’s unsure if the patient will benefit from the non-skeletal effects of vitamin D at this dose. For patients with AIDS, on chronic corticosteroid therapy, or taking anti-convulsants, or anti-fungals the daily dose of vitamin D should be anywhere from double to triple the normal suggested value for that patients age group. If the patient would happen to be deficient, the suggested replacement regimen is 50,000 IU of vitamin D2 or D3 orally once weekly for 6-8 weeks followed by the routine maintenance dose. This may vary based on patient specific parameters such as absorption. For every 100 IU of vitamin D3 given to the pt, it is expected to increase the 25 (OH) lab value by 1 ng/mL. 
As with any medication, there are associated risks that accompany the benefits.  Although vitamin D toxicities are rare, it is a possibility with the ingestion of large amounts of high strengths of the vitamin. When 25 (OH) levels are >150 ng/mL the patient is at risk for hypercalcemia, hypercalciuria, kidney stones, calcification of the kidney with renal failure, which can ultimately lead to death.  Also before recommending any medication, it is important to obtain a complete medication list that includes prescription, OTC, herbals, and supplements which could also contain vitamin D. Caution should be used with vitamin D2 supplementation in patients with impaired kidney function/kidney stones, high phosphate, calcium, or vitamin D levels, malabsorption syndrome, CV disease, hypersensitivity/allergy to components of the drug. These recommendations are only meant to serve as template of treatment for the supplementation of vitamin D and therapy should be individualized to each specific patient with collaboration of the physician, pharmacist, or other health care provider.

References:
Holick MF, Binkley NC, Bischoff-Ferrari HA, Gordon CM, Hanley DA, Heaney RP, Murad MH, Weaver CM, Endocrine Society. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline.  J Clin Endocrinol Metab. 2011 Jul; 96(7):1911-30.
Lexicomp Online [database on the internet]. Hudson (OH): Lexicomp. 2013 [cited 2013 June 25]. Available from: http://0-online.lexi.com.polar.onu.edu/lco/action/home;
O’Connell MB, Vondracek SF. Chapter 99. Osteoporosis and Other Metabolic Bone Diseases. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 8th ed. New York: McGraw-Hill; 2011. http://0-www.accesspharmacy.com.polar.onu.edu/content.aspx?aID=7996689. Accessed June 25, 2013
University of Texas at Austin, School of Nursing, Family Nurse Practitioner Program. Recommendations for the diagnosis and
management of vitamin D deficiency in adults. Austin (TX): University of Texas at Austin, School of Nursing; 2009 May. 16 p.

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