LETTER
Bone Density and Vitamin D Intoxication
Malachi J. McKenna, MD, and
Rosemarie Freaney, PhD
15 March 1998 | Volume 128 Issue 6 | Pages 507-508
TO THE EDITOR:
Hypovitaminosis D in the elderly is a worldwide problem [1]. No evidence suggests that supplementation with parent vitamin D (either low-dose continuous or high-dose intermittent therapy) in the elderly is dangerous [2], but high doses taken over long periods predispose recipients to hypercalcemia. Even community-dwelling elderly persons benefit from daily administration of calcium (500 mg) and vitamin D (700 IU) [3]. Adams and Lee [4] report four cases of hypervitaminosis D due to vitamin D intake from multivitamin and dietary supplements. No effort is made to provide even an estimate of vitamin D intake. This is unacceptable at a time when authorities in many countries are recommending vitamin D intakes of 600 to 800 IU daily and when attempts are being made to define the tolerable upper intake level, as mentioned in the editorial accompanying Adams and Lee's report [5].
That the reduction in 25(OH)D levels and the increase in bone mineral density were contemporaneous events does not indicate a causal relation, especially because two of the patients received estrogen. Osteopenia is expected in patients who were referred with suspected osteoporosis. No baseline measurements before initiation of vitamin D and calcium therapy were obtained, and no data are given on bone remodeling. An elevated fasting urine calcium-to-creatinine ratio is a surrogate for hypercalciuria, which is determined by 24-hour urine excretion. It is more plausible to conclude that the increase in bone density was a residual effect of pharmacologic doses of vitamin D in conjunction with calcium supplementation, although the contribution of estrogen cannot be ignored. Thus, there is no need to screen osteopenic patients for hypervitaminosis D unless they are receiving pharmacologic doses of vitamin D.
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Author and Article Information
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St. Vincent's Hospital; Dublin 4, Ireland
1. McKenna MJ. Differences of vitamin D status between various countries in young adults and the elderly. Am J Med. 1992; 93:69-77.
2. Byrne P, Freaney R, McKenna MJ. Vitamin D supplementation in the elderly: safety and effectiveness of various regimes. Calcif Tissue Int. 1995; 56:518-20.
3. Dawson-Hughes B, Harris SS, Krall EA, Dallal GE. Effect of calcium and vitamin D supplementation on bone density in men and women 65 years of age and older. N Engl J Med. 1997; 337:670-6.
4. Adams JS, Lee G. Gains in bone mineral density with resolution of vitamin D intoxication. Ann Intern Med. 1997; 127:203-6.
5. Marriott BM. Vitamin D supplementation: a word of caution [Editorial]. Ann Intern Med. 1997; 127:231-3.
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