UMLS:C0020437 - FACTA Search

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Query: UMLS:C0020437 (hypercalcemia)
10,293 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Renal osteodystrophy is the term used to describe the spectrum of bone diseases associated with chronic renal failure. Deficiency of 1,25-dihydroxycholecalciferol (calcitriol) plays a major role in the development of renal osteodystrophy, in particular the evolution of secondary hyperparathyroidism. In recent decades, our understanding of the complex interactions between calcium, phosphorus, vitamin D, and parathyroid hormone (PTH) has increased, resulting in a rational approach to therapy in which vitamin D analogs have become an essential component. The initial vitamin D analogs that have been in widespread clinical use include calcitriol (1,25-[OH](2)D(3)) and alfacalcidol (1alpha-[OH]D(3)). These agents have been extensively studied to optimize their effects on secondary hyperparathyroidism. The occurrence of significant hypercalcemia and hyperphosphatemia limiting their use has led to the development of alternative vitamin D analogs that effectively reduce PTH secretion without causing these complications. Recently, 3 such analogs, 22-oxa-1,25-(OH)(2)D(3) (OCT), 1alpha-(OH)D(2) (doxercalciferol), and 19-nor-1,25-(OH)(2)D(2) (paricalcitol), have been released for clinical use. Only paricalcitol has been studied in comparative human clinical trials with calcitriol in dialysis patients. Preliminary findings suggest a clinical advantage over calcitriol, however, analysis of the larger comparative studies are forthcoming.
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PMID:Use of vitamin D analogs in chronic renal failure. 1220 99

Musculoskeletal problems remain among the main limitations of the quality of life of renal failure patients, in particular of those treated with long-term maintenance dialysis. Renal osteodystrophy continues to receive great attention. The mechanisms of uremic skeletal resistance to parathormone (PTH) are further investigated. The assay used for the dosage of "intact PTH" has been found to detect 7-84 fragments with an inhibitory effect on the action of the whole hormone. A decrease in the density of PTH receptor on osteoblasts is another recently evidenced factor. Investigations of the recently described RANK-RANKL system have demonstrated an increase in serum osteprotegerin levels, which, together with the two above-mentioned abnormalities, may explain bone resistance to PTH. These are important advances in the understanding of renal osteodystrophy as skeletal resistance to PTH appears to play an important part in the pathophysiology of secondary hyperparathyroidism and of adynamic bone disease. Because of this skeletal resistance, it has been recommended for several years that serum PTH level be monitored and kept twofold to threefold above the upper value of the normal level to maintain normal bone turnover in dialysis patients. Relative hypoparathyroidism has recently been found to be associated with increased spontaneous fracture rate and mortality, so this recommendation appears to hold adequate, despite the demonstration that serum PTH levels in this range are a poor predictor of bone turnover and that chronic parathyroid gland hyperplasia is likely to favor parathyroid gland autonomization. Recent publications have insisted on the role that hyperphosphatemia plays not only in the development of secondary hyperparathyroidism, but also of vascular, especially coronary, calcification and as a predictor of mortality. This "silent killer" of uremic patients is one of the main targets for therapeutic intervention. Extensive use of calcium-containing phosphate binders has been recently criticized as calcium overload appears to favor vascular calcification. Sevelaner (RenaGel) is a calcium- and aluminum-free phosphate binder that is an important advance in the management of renal osteodystrophy, especially in patients with extraskeletal calcification and hypercalcemia. The use of vitamin D derivatives has also raised concern because they enhance calcium and phosphorus absorption and reduce bone turnover. New metabolites with fewer hypercalcemic effects have been developed. Calcium-sensing receptor agonists are stimulating interest and are likely to take an important place in the future management of renal osteodystrophy. Uremic myopathy has received recent attention. Impaired muscle capillary oxygen transfer has been identified as a pathophysiologic factor, and progressive resistance training has been shown to improve the condition. Finally, a new entity, nephrogenic fibrosing dermopathy, has been described, which must be distinguished from calciphylaxis and scleromyxedema.
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PMID:Musculoskeletal manifestations of chronic renal failure. 1249 10

Abnormalities in calcium and phosphorus metabolism are common, and metabolic bone disease develops often in patients with chronic renal failure (CRF). Effective clinical management includes measures to control phosphorus retention and prevent hyperphosphataemia, to maintain serum calcium concentrations within the normal range and to prevent excess parathyroid hormone (PTH) secretion by the judicious use of vitamin D sterols. Certain of these interventions appear to increase the risk of soft tissue and vascular calcification in patients with end-stage renal disease (ESRD), changes that may contribute to the development of cardiovascular disease. Current therapeutic approaches are thus being re-evaluated in an effort to limit these risks. Despite the importance of controlling phosphorus retention and preventing hyperphosphataemia in patients with CRF, current management strategies often are inadequate, particularly in those ingesting diets containing adequate amounts of protein. Results from clinical trials using daily haemodialysis strongly suggest that thrice-weekly haemodialysis regimens are only marginally adequate for achieving weekly phosphorus balance in many patients with ESRD. The safety of large oral doses of calcium as a phosphate-binding agent in patients with ESRD has also been questioned because excess amounts of calcium that are absorbed from the gastrointestinal tract may lead to ongoing calcium retention in those with little or no residual renal function. Arterial calcification and cardiac valve calcification are two serious complications that adversely affect cardiovascular haemodynamics. The use of large, often supraphysiological, doses of calcitriol or other vitamin D sterols to treat secondary hyperparathyroidism may aggravate hypercalcaemia and hyperphosphataemia, further increasing the risk of soft tissue and vascular calcification. Phosphate-binding agents that do not contain calcium, new vitamin D analogues and calcimimetic compounds offer new therapeutic alternatives for managing renal osteodystrophy. The integration of these novel agents into existing treatment regimens may provide safer and more effective methods for controlling secondary hyperparathyroidism and renal bone disease, while limiting the risks of soft tissue and vascular calcification in patients with CRF.
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PMID:Medical management of secondary hyperparathyroidism in chronic renal failure. 1277 Dec 90

It has become readily apparent to many scientists and pharmaceutical companies that the vitamin D endocrine system offers a wide array of drug development opportunities. There are already successes, as noted by 1alpha,25(OH)2D3 (Roche, and Abbott) for renal osteodystrophy and osteoporosis and 1alpha(OH)D3 (Leo, Chugai, Teijin) for renal osteodystrophy and (in Japan) osteoporosis, 1alpha,24(OH)2-24-cyclopropyl-D3 (Dovonex) and 1alpha,24(OH)2D3 (Teijin) for psoriasis, and 19-nor-1alpha,25(OH)2D2 (Abbott) for renal osteodystrophy, as well as drugs under active development. Yet there are still many important and challenging drug development frontiers, particularly in the area of cancer treatment and immune system disorders where exploration is only in the initial early stages. In addition, the application of vitamin D-related drugs in neurology and brain pathology should not be overlooked. It is to be hoped that the cellular and molecular basis for the vexing problem of analog-induced hypercalcemia will be elucidated. Given that there are believed to be over 2000 analogs of 1alpha,25(OH)2D3 already available for consideration, it is to be expected that over the next decade a significant number of new vitamin D structure-function drug development projects will be brought to conclusion.
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PMID:Ligand structure-function relationships in the vitamin D endocrine system from the perspective of drug development (including cancer treatment). 1289 14

Phosphate (Pi) retention is a common problem in patients with chronic kidney disease, particularly in those who have reached end-stage renal disease (ESRD). In addition to causing secondary hyperparathyroidism and renal osteodystrophy, recent evidence suggests that, in ESRD patients, high serum phosphorus concentration and increased calcium and phosphorous (Ca x P) product are associated with vascular and cardiac calcifications and increased mortality. Dietary phosphorus restriction and Pi removal by dialysis are not sufficient to restore Pi homeostasis. Reduction of intestinal Pi absorption with the use of Pi binders is currently the primary treatment for Pi retention in patients with ESRD. The use of large doses of calcium-containing Pi binders along with calcitriol administration may contribute to over-suppression of parathyroid hormone secretion and adynamic bone disease as well as to a high incidence of vascular calcifications. When used in patients with impaired renal function, aluminium salts were found to accumulate in bone and other tissues, resulting in osteomalacia and encephalopathy.Sevelamer, an aluminium- and calcium-free Pi binder can reduce serum phosphorus concentration and is associated with a significantly lower incidence of hypercalcaemia, while maintaining the ability to suppress parathyroid hormone production. An additional benefit of sevelamer is its ability to lower low density lipoprotein-cholesterol and total cholesterol levels. Sevelamer attenuates the progression of vascular calcifications in haemodialysis patients, which may lead to lower mortality. The use of sevelamer in non-dialysed patients might aggravate metabolic acidosis, common in these patients. Several other calcium-free Pi binders are in development. Lanthanum carbonate has shown significant promise in clinical trials in ESRD patients. Magnesium salts do not offer a significant advantage over currently available Pi binders. Their use is restricted to patients receiving dialysis since excess magnesium must be removed by dialysis. Iron-based compounds have shown variable efficacy in short-term clinical trials in small numbers of haemodialysis patients. Mixed metal hydroxyl carbonate compounds have shown efficacy in animals but have not been studied in humans. Major safety issues include absorption of the metal component with possible tissue accumulation and toxicity.
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PMID:Safety of new phosphate binders for chronic renal failure. 1464 Jul 73

A preliminary study of the intact-parathyroid hormone (i-PTH) measurements from haemodialysis patients was conducted to determine the prevalence of renal bone diseases at the Dr Soetomo Hospital. The objective of this study is to evaluate the osteodystrophy renal pattern in haemodialysis patients using i-PTH and radiological parameters. The selected populations of 48 (32 males and 16 females), the mean age 48 +/- 10.3 years, was evaluated to conduct a cross-sectional study. The calorimetric method was applied to measure serum P and Ca, while a radioimmunoassay was used to assay the i-PTH level. Of those 48 patients receiving haemodialysis, with a duration ranging from 4 to 432 weeks, 61% had hypocalcaemia and 10% had hypercalcaemia. The i-PTH levels below 100 pg/mL (normal, 10-65 pg/mL) suggested 'aplastic' bone, and values of 100-200 pg/mL most commonly indicated 'normal' bone turnover. The i-PTH levels over 200 pg/mL suggested hyperparathyroidism. The results of this study demonstrated that 42% of those patients had <100 pg/mL (low turnover bone presumed, no biopsy), 23% had 100 - <200 pg/mL ('normal' bone turnover) and 35% of them had >200 pg/mL ('hyperparathyroidism'). In addition, the radiological study showed that 10% of those patients were positive for renal bone diseases. In conclusion, this study shows that the common type of renal osteodystrophy was of a low turnover type, which was different from the findings in other previous studies. It is postulated that this difference is likely to be caused by some factors such as the general health condition of the population those patients belong to and, in particular, the nutritional status of those patients.
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PMID:Osteodystrophy in Indonesian haemodialysis patients. 1501 15

In the early stages of renal failure, hyperparathyroidism develops as a compensatory mechanism to control serum levels of calcium, phosphorus and calcitriol. As kidney disease progresses, this ability to maintain mineral homeostasis is lost, leading to the development of renal osteodystrophy (ROD). Over the past decade, the pattern of ROD seen in patients with chronic kidney disease (CKD) has changed. Previously, the majority of patients had mixed uraemic osteodystrophy or aluminium-related osteomalacia. The decreased use of aluminium-based phosphate binders, coupled with improvements in the management of hyperphosphataemia, led to a reduction in the prevalence of these types of ROD. Since the mid-1990s, there has been an increase in the prevalence of adynamic bone disease as a result of increased suppression of parathyroid hormone through the use of calcium-based phosphate binders and calcitriol therapy. Adynamic bone disease is also associated with several clinical factors, such as older age, use of continuous ambulatory peritoneal dialysis and the presence of diabetes mellitus, as well as the use of calcitriol therapy. Studies of calcium metabolism in patients with CKD have shown that adynamic bone disease is a distinct clinical condition that leads to hypercalcaemia via mechanisms different from that seen in high-turnover bone disease. As high calcium x phosphorus product has been associated with soft tissue and vascular calcifications, and increased mortality, optimizing bone health may be an important way of reducing cardiovascular risk in patients with CKD. To do this, novel, effective, non-calcium, non-aluminium phosphate binders will be necessary.
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PMID:The importance of bone health in end-stage renal disease: out of the frying pan, into the fire? 1512 48

Aluminium- or calcium-based phosphate-binding agents traditionally have been used to treat hyperphosphataemia in patients with end-stage renal disease. Although these agents effectively lower serum phosphorus levels, they are associated with serious side effects. Aluminium-based agents are associated with bone toxicity, renal osteodystrophy and encephalopathy, and calcium-based agents increase the risk of hypercalcaemia and cardiovascular calcification. Consequently, there remains a need for new, safe and effective non-calcium-, non-aluminium-based alternative treatments. Fortunately, several new agents are now available or are in the late stages of development, including sevelamer hydrochloride and lanthanum carbonate. Although sevelamer hydrochloride represents a step forward in the management of hyperphosphataemia, it has several drawbacks and is far from being the ideal phosphate binder. Lanthanum carbonate is the most recent non-calcium, non-aluminium phosphate binder to be developed for the treatment of hyperphosphataemia. Animal studies have shown it to be as effective as aluminium, without the associated toxicity. In clinical studies, lanthanum carbonate significantly reduced serum phosphorus levels, compared with placebo. It shows a similar efficacy to calcium carbonate in controlling serum phosphorus levels, but requires lower doses. In addition, lanthanum carbonate is at least as well tolerated as calcium carbonate, but is not associated with hypercalcaemia. Importantly, it has a positive effect on bone histology, with no evolution towards low bone turnover. Lanthanum carbonate, therefore, moves closer to the ideal phosphate binder.
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PMID:Improving phosphate-binder therapy as a way forward. 1512 50

Suppression on both bone formation and absorption is a characteristic histology of adynamic (or aplastic) bone (ABD). This new entity of renal osteodystrophy started to appear in bone biopsy findings in 1983. Most significant etiology of adynamic bone is relatively lower serum PTH level. Any study has failed to demonstrate that ABD would increase the incidence of bone fracture in dialysis patients. However, ABD increases the risk of hypercalcemia because a decrease in calcium uptake by bone and might shorten the life span of dialysis patients.
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PMID:[Clinical characteristic of adynamic bone]. 1577 88

Repeated intervenous calcitriol administration is an established treatment for renal osteodystrophy. However, the therapeutic effects of this treatment vary among patients, and it cannot be administered to patients with hypercalcemia. This time, we investigated the relationship between dialysate dose and the effects of intervenous calcitriol administration. The results demonstrated that normal-calcium dose dialysate is more useful than low-calcium dose dialysate.
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PMID:[Not Available]. 1577 2

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