Treating vitamin D deficiency
Treatment of vitamin D deficiency or insufficiency (low D) is usually achieved either through sunlight exposure or vitamin D supplements. Sunlight exposure requirements vary based on skin pigmentation. For example, a white infant clothed in a diaper can achieve adequate amounts of sunlight exposure in 30 minutes compared with a black person, who would require nearly three times this amount of exposure to obtain the same benefits.6 Such exposure will provide an estimated 1,000 IU of vitamin D3, an amount that is likely to be inadequate for those with darker skin and the elderly because of decreased dermal conversion.Available vitamin D supplements include ergocalciferol and cholecalciferol. Ergocalciferol, which is available by prescription, is supplied as 50,000 IU and usually dosed weekly or monthly, depending on the degree of deficiency. Cholecalciferol is available OTC in doses ranging from 400-5,000 IU and usually taken as a daily supplement. Recommendations from the IOM and The Endocrine Society guidelines indicate that the daily vitamin D intake for adults aged 18-50 years should be 600 IU, with an upper limit of 4,000 IU per day.7 The recommended amount for persons who are at high risk (those with dark skin and the elderly) and lack adequate sun exposure is 800-1,000 IU daily.
Once vitamin D deficiency or insufficiency has been determined, treatment with the appropriate amount of vitamin D is necessary. For those who are deficient, the recommendation is for initial treatment with 50,000 IU of ergocalciferol or cholecalciferol weekly for six to eight weeks, then 800-1,000 IU of cholecalciferol daily or IM cholecalciferol (300,000 IU) once or twice a year. In cases of insufficiency, treatment with 800-1,000 IU of cholecalciferol daily should improve vitamin D levels in about three months. The IOM provides recommendations for daily calcium and vitamin D intakes during various life stages (Table 5).
Among the available supplements, calcium citrate is the most easily absorbed and best tolerated by patients with low levels of stomach acid. Recommendations also limit the amount of calcium taken at one time to no more than 500 mg in order to enhance absorption. Therefore, patients who require 1,000 mg of calcium per day should take it in divided doses. Sustained-release calcium is available, which allows for once-daily dosing.
Cautions and intoxication
Although intoxication with vitamin D is rarely seen, it is a possibility. Intoxication usually occurs at levels >150 ng/mL. According to NIH, levels consistently greater than 200 ng/mL are considered toxic. The intoxication syndrome comprises hypercalciuria, hypercalcemia, renal stones, renal calcifications, renal failure, and death. Nonspecific symptoms of intoxication include anorexia, weight loss, polyuria, arrhythmias, and hypercalcemia—resulting in damage to the cardiac blood vessels and kidneys. The use of calcium and vitamin D supplements by postmenopausal women has been associated with a 17% increased risk of kidney stones over seven years.8Exercise caution when initiating ergocalciferol in patients with hypophosphatemia, malabsorption syndromes, CVD, renal stones, and impaired renal function. The use of ergocalciferol is contraindicated in persons with hypercalcemia, hypersensitivity to the drug, its components, or class; renal osteodystrophy; and hypervitaminosis D.
Maintenance of adequate vitamin D levels appears to be beneficial to patients across the life span. While obtaining a 25(OH)D level at each office visit is currently not the standard of care, exploration of the health benefits of adequate levels of vitamin D may result in a change in recommended care in the very near future. If there is a family history of vitamin D deficiency or if the patient falls into one of the risk categories indicated in Table 3, he or she may well benefit from being screened. Although no guidelines state clearly how often vitamin D level determinations should be repeated, our practice at MD Anderson Cancer Center is to monitor every three to six months until sufficient levels are obtained and then at least yearly thereafter. Once serum vitamin D levels are satisfactory, a maintenance dose of vitamin D should be taken daily (or weekly). Along with adequate intake of vitamin D and calcium, patients should be encouraged to perform weight-bearing exercise and stop smoking. Preventing falls is key among the elderly population, and moderation in alcohol intake should be discussed.
Veronica Brady, MSN, FNP-BC, BC-ADM, CDE, is a nurse practitioner in the Department of Endocrine Neoplasia and Hormonal Disorders at the University of Texas, MD Anderson Cancer Center, in Houston.
- Khan QJ, Fabian CJ. How I treat vitamin D deficiency. J Oncol Pract. 2010;6:97-101.
- Rao DS. Clinical practitioner perspective. In: Burnstein KL, Ehrmann D, eds. Vitamin D: Beyond Bone: Other Benefits. Endocrine News. 2010;35:18-23.
- Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2011;96:1911-1930.
- Epplin J, Thomas SA. Vitamin D: it does a body good. Ann Long Term Care: Clin Care and Aging. 2010;18:39-45.
- Agency for Healthcare Research and Quality. Recommendations for the diagnosis and management of vitamin D deficiency in adults. 2009.
- Pazirandeh S, Burns DL, Lipman, TO, et al. Overview of vitamin D.
- Ross AC, Manson JE, Abrams SA, et al. The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know. J Clin Endocrinol Metab. 2011;96:53-58.
- Jackson RD, LaCroix AZ, Gass M, et al. Calcium plus vitamin D supplementation and the risk of fractures. N Engl J Med. 2006;354:669-683.
All electronic documents accessed August 15, 2012.