George James | PubMed Health

PubMed2004

Decrease in thoracic vertebral bone attenuation with calcium-based phosphate binders in hemodialysis.

UNLABELLED: We performed a post hoc analysis of a 52-week randomized trial conducted in adult hemodialysis patients that compared the effects of calcium-based phosphate binders and sevelamer, a nonabsorbable polymer, on parameters of mineral metabolism and vascular calcification by electron beam tomography. In this analysis, we evaluated the relative effects of calcium and sevelamer on thoracic vertebral attenuation by CT and markers of bone turnover. Subjects randomized to calcium salts experienced a significant reduction in trabecular bone attenuation and a trend toward reduction in cortical bone attenuation, in association with higher concentrations of serum calcium, lower concentrations of PTH, and reduced total and bone-specific alkaline phosphatase. INTRODUCTION: In patients with chronic kidney disease, hyperphosphatemia is associated with osteodystrophy, vascular and soft tissue calcification, and mortality. Calcium-based phosphate binders are commonly prescribed to reduce intestinal phosphate absorption and to attenuate secondary hyperparathyroidism. Clinicians and investigators have presumed that, in hemodialysis patients, calcium exerts beneficial effects on bone. MATERIALS AND METHODS: We performed a post hoc analysis of a 52-week randomized trial conducted in adult hemodialysis patients that compared the effects of calcium-based phosphate binders and sevelamer, a nonabsorbable polymer, on parameters of mineral metabolism and vascular calcification by electron beam tomography. In this analysis, we evaluated the relative effects of calcium and sevelamer on thoracic vertebral attenuation by CT and markers of bone turnover. RESULTS AND CONCLUSIONS: The average serum phosphorus and calcium x phosphorus products were similar for both groups, although the average serum calcium concentration was significantly higher in the calcium-treated group. Compared with sevelamer-treated subjects, calcium-treated subjects showed a decrease in thoracic vertebral trabecular bone attenuation (p = 0.01) and a trend toward decreased cortical bone attenuation. More than 30% of calcium-treated subjects experienced a 10% or more decrease in trabecular and cortical bone attenuation. On study, sevelamer-treated subjects had higher concentrations of total and bone-specific alkaline phosphatase, osteocalcin, and PTH (p < 0.001). When used to correct hyperphosphatemia, calcium salts lead to a reduction in thoracic trabecular and cortical bone attenuation. Calcium salts may paradoxically decrease BMD in hemodialysis patients.

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PubMed2004

Coronary calcium screening and coronary risk stratification.

Current vital statistics clearly indicate a continuing epidemic of cardiovascular disease in the Western hemisphere and strongly suggest that the most desirable approach to this ailment is prevention rather than delayed treatment. Over 7 million people in the United States suffer from coronary artery disease and more than 500,000 die from its complications annually. In the majority of cases, the event announcing the presence of atherosclerosis is either sudden death or a disabling myocardial infarction or stroke. Though recent trials indicate a need for treatment of very large segments of the population, a review of current clinical practices indicates that the preventive attitude of the majority of physicians is not sufficiently developed and remains limited in most training programs. Additionally, although traditional risk factors are very helpful in predicting the development of cardiovascular disease, many individuals suffer events in the absence of established risk factors for atherosclerosis. To meet the challenge of coronary artery disease, several tools have been developed to identify atherosclerotic disease in its preclinical stages, with the hope of modifying its natural history. In this article, we review the current literature on utilization of electron beam tomography for detection of coronary artery calcification as a tool to conduct risk stratification for coronary artery disease events in the general population.

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