Should Vitamin D Screening Be Routine in All CVD Patients?

Abstract & Commentary

By Harold L. Karpman, MD, FACC, FACP. Dr. Karpman is Clinical Professor of Medicine, UCLA School of Medicine; he reports no financial relationship to this field of study. This article originally appeared in the Feb. 29, 2009, issue of Internal Medicine Alert. For that publication, it was peer reviewed by Gerald Roberts, MD, Assistant Clinical Professor of Medicine, Albert Einstein College of Medicine, Bronx, NY; Dr. Roberts reports no financial relationship to this field of study.

Synopsis: Hypovitaminosis D was found to be highly prevalent in U.S. adults with CVD, particularly those with both coronary heart disease and heart failure.

Source: Kim DH, et al. Prevalence of hypovitaminosis D in cardiovascular diseases (from the National Health and Nutrition Examination Survey 2001 to 2004). Am J Cardiol 2008;102:1540-1544.

Vitamin d deficiency occurs in one-third to one-half of otherwise healthy middle-aged and elderly adults in the United States and worldwide. There is a growing body of evidence that hypovitaminosis D is highly prevalent in patients with various cardiovascular diseases (CVDs)1-4 and, in fact, it may actually play a role in the pathogenesis of these illnesses.5-9 Inadequate exposure to sunlight and/or inadequate vitamin D intake will result in abnormally low serum vitamin D levels, which have been found to be associated with cardiovascular risk factors such as hypertension, diabetes mellitus, obesity, and dyslipidemia;10,11 however, it must be recognized that many of these observations were from the results of relatively small studies.

Because the degree of occurrence of hypovitaminosis D in adults in the United States with a diagnosis of CVD was largely unknown, Kim and his colleagues examined its prevalence in U.S. adults with CVDs using data from the National Health and Nutrition Examination Surveys (NHANES) from 2001 to 2004.12 Hypovitaminosis D was found to be present in 74% of the 8,351 adults who had 25-hydroxyvitamin D (25-OH D) blood levels measured. Among CVD patients it was more common in blacks than it was in Hispanic or Caucasian patients and it did not differ by gender. However, although it was found to be present in 68% of persons at low risk for CVDs, low vitamin D levels were more prevalent in high-risk patients (75%), in patients with coronary heart disease (77%), and in subjects with both coronary heart disease and heart failure (89%) after controlling for age, race, and gender.

Commentary

Several lines of evidence have suggested that hypovitaminosis D may contribute to CVDs by stimulating renin expression,13 proliferation of cardiomyocytes,14 and smooth muscle cells15 and by producing secondary hyperparathyroidism16 and inflammation.17 Although the higher prevalence of hypovitaminosis D in patients with coronary heart disease and heart failure may have been caused by limited physical activity and sunlight exposure, studies have demonstrated that patients with heart failure compared to healthy controls differed in their lifestyle factors even in their earlier years, suggesting that hypovitaminosis D may occur earlier in life and precede the onset of CVDs.18

The Kim observational study revealed that hypovitaminosis D was highly prevalent in U.S. adults with CVDs, particularly those with both coronary heart disease and heart failure.12 In addition, the results raise the clinical possibility that treatment of vitamin D deficiency with vitamin D supplements and/or lifestyle measures might reduce the frequency of CVDs; however, it must be clearly recognized that treatment strategies suggested by observational data are not always supported by randomized trials. Despite the positive results in small clinical trials in which vitamin D supplementation has promoted reductions in blood pressure,19,20 left ventricular hypertrophy,21 and inflammatory cytokines,22 vitamin D supplementation was not associated with a reduction in cardiovascular events in the Woman's Health Initiative,23 although it should be noted that that particular trial was not designed to evaluate cardiovascular risk.24 Obviously, although well constructed, randomized, double-blinded clinical studies are needed to conclusively determine whether correction of vitamin D deficiency is able to contribute to the prevention and treatment of CVDs, at the present time there seems to be little risk for clinicians to recommend at least 800 IU of vitamin D daily for their adult (and especially elderly) patients and to consider prescribing even higher doses of vitamin D if needed to correct persistently abnormally low vitamin D blood levels, especially for those patients whose lifestyle and/or illnesses prevent them from being outdoors.

References

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19. Lind L, et al. Reduction of blood pressure during long-term treatment with active vitamin D (alphacalcidol) is dependent on plasma renin activity and calcium status; a double-blind placebo-controlled study. Am J Hypertens 1989;2:20-25.

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21. Park CW, et al. Intravenous calcitriol regresses myocardial hypertrophy in hemodialysis patients with secondary hyperparathyroidism. Am J Kidney Dis 1999;33:73-81.

22. Schleithoff SS, et al. Vitamin D supplementation improves cytokine profiles in patients with congestive heart failure: A double-blind, randomized, placebo-controlled trial. Am J Clin Nutr 2006;83:754-759.

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24. Michos ED, et al. Vitamin D supplementation and cardiovascular disease risk. Circulation 2007;115: 827-828.