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 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nephrocalcinosis is a chronic tubulointerstitial nephropathy characterized by tubular calcium phosphate deposition and slowly progressive renal insufficiency. We report a novel association of acute nephrocalcinosis and acute renal failure (ARF) with colonoscopy preceded by a bowel-cleansing regimen consisting of oral sodium phosphate solution (OSPS). A cohort of 5 patients (mean age, 69.2 years) had normal renal function (mean serum creatininem 0.9 mg/dL) before colonoscopy and presented with ARF (mean serum creatinine, 4.9 mg/dL) from 3 days to 2 months postcolonoscopy. Past medical history included hypertension in all 5 patients. Medications included an angiotensin-converting enzyme (ACE) inhibitor (ACE-I) or angiotensin receptor blocker (ARB) in 4 patients and diuretics in 2 patients. In all patients, colonoscopy was preceded by bowel cleansing with OSPS; OSPS was contraindicated in a single patient with hyperparathyroidism and was used at excessive doses in another. Renal biopsy specimens obtained from all 5 patients revealed diffuse tubular injury and abundant tubular deposition of calcium phosphate. Although the tubular injury involved all tubular segments, lectin and immunohistochemical staining disclosed calcium phosphate deposition confined to distal tubules and collecting ducts. At a mean of 5.8 weeks of postbiopsy follow-up, renal function was unchanged in 4 patients and mildly improved in 1 patient. We conclude that acute nephrocalcinosis is a seemingly rare complication of bowel cleansing with OSPS. The pathophysiology of acute nephrocalcinosis after treatment with OSPS likely involves transient hyperphosphatemia; volume depletion exacerbated by intercurrent ACE-I, ARB, and diuretic use; and elevated distal tubular phosphate and calcium concentrations. Greater awareness of this entity is needed to identify potential risk factors.
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PMID:Renal failure due to acute nephrocalcinosis following oral sodium phosphate bowel cleansing. 1716 33

Cardiovascular diseases are the leading causes of mortality among patients with end-stage renal disease (ESRD), with arterial disease and left ventricular hypertrophy being the two principal factors of the high mortality rate in this population. In addition to traditional risk factors (age, gender, diabetes, hypertension, lifestyle, hyperlipidemia, smoking, hyperhomocystinemia), inflammation, oxidative stress and disorders of mineral metabolism may contribute to cardiovascular risk in patients with uremic syndrome. High serum phosphate may influence vascular calcifications directly and indirectly, by worsening secondary hyperparathyroidism. Several treatment options are available for the treatment of hyperphosphatemia and secondary hyperparathyroidism in patients with ESRD. The treatment approach includes a diet low in phosphorus, with less than 1 g/kg/day of protein. Vitamin D supplementation is an important part of treatment. Phosphate binding agents are in most of the patients necessary in addition to diet. Aluminum hydroxide has been widely used for many years. It is very potent, but also very toxic, with severe encephalopathy as the most dangerous side effect. Calcium salts are less potent, and were considered safe for use in patients on dialysis. However, improvement in the understanding of vascular calcifications has demonstrated that calcium overload significantly contributes to widespread atherosclerosis in patients with ESRD. Sevelamer-hydrochloride is a novel non-aluminum, non-calcium containing phosphate binder, which is capable of reducing the levels of phosphorus as well as of low-density lipoprotein cholesterol, and increasing high-density lipoprotein cholesterol.
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PMID:[Hyperphosphatemia and cardiovascular risk in patients on dialysis]. 1550 84

Patients with end-stage renal disease have greatly elevated risks of atherosclerotic disease. Vascular calcification in advanced atherosclerosis is a common feature in ESRD patients. Risk factors of atherosclerosis in ESRD patients are coronary risk factors such as hypertension, diabetes and hyperlipidemia and hyperphosphatemia. Bone associated proteins including osteopontin, matrix Gla protein and osteoprotegerin may be involved in the progression of atherosclerosis.
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PMID:[Risk factors of atherosclerosis in end-stage renal disease patients]. 1557 49

Vascular calcifications are more frequent in dialysis patients than in the general population or in patients with cardiovascular disease (CVD) and normal renal function. The reasons for this high incidence are multiple; they include traditional factors such as hypertension, diabetes, dyslipidemia, and specific factors such as sodium overload, hyperomocysteinemia, chronic inflammation and oxidative stress, as well as mineral metabolism disturbances. Specifically, hyperphosphatemia and the elevated calcium (Ca) x phosphate product have been associated with an increased risk for the development of vascular calcification and death. Treatment with Ca salts can induce hypercalcemia, increased Ca x phosphate product and Ca overload. Sevelamer substitution for Ca salts has been documented to attenuate the progression of coronary artery and aortic calcification. A possible mechanism explaining this observation could be ongoing Ca loading related to oral Ca ingestion. Treatment with Ca salts could induce Ca overload, particularly in patients dialyzed against a high dialysate Ca (>1.5 mmol/L) solution, which is known to determine a positive dialysis balance. Conversely, an overall negative Ca balance can result from low Ca dialysate use (1.25 mmol/L) when the patients do not receive Ca supplements or vitamin D metabolites. Maintaining normal Ca and phosphate balances remains a primary goal in the management of dialysis patients. Control of hyperphopshataemia should be achieved either using Ca and aluminum-free phosphate binders, such as sevelamer, or Ca salts, alone or in combination, provided that a daily oral elemental Ca intake of 1.5 g is not exceeded.
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PMID:[Control of calcium and phosphate metabolism and prevention of vascular calcifications in uremic patients]. 1578 2

Patients treated for end stage renal disease (ESRD) have a shorter life expectancy and a poorer quality of life than the general population. In an attempt to improve outcomes for this patient population, a few novel therapeutic approaches have been undertaken. With hemodialysis, an increase in dialysis frequency and/or time has been associated with improvements in anemia, left ventricular hypertrophy, hypertension, hyperphosphatemia, nutrition and quality of life. Yet, access to these promising hemodialysis modalities has remained limited. The reasons for this are numerous, but one concern is the potential for more frequent vascular access complications with the increased frequency of cannulation for an arteriovenous fistula/graft and connection for a central venous catheter. In this systematic review of the literature, we identified all published studies that included 10 or more patients on daily hemodialysis and reported quantitative data pertaining to vascular access complications. Twelve studies met our inclusion criteria. The overall complication rates associated with vascular access do not appear to be increased and are perhaps even decreased with daily compared to conventional thrice-weekly hemodialysis. Arteriovenous fistulas are the vascular access of choice for daily hemodialysis; however, a non-statistically significant increased complication rate for these accesses was reported in 2 North American studies. The reasons for this are unclear and require further research.
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PMID:Vascular access complications in daily dialysis: a systematic review of the literature. 1598 14

The findings of diffuse tubular injury with abundant tubular calcium phosphate deposits on renal biopsy are referred to as nephrocalcinosis, a condition typically associated with hypercalcemia. During the period from 2000 to 2004, 31 cases of nephrocalcinosis were identified among the 7349 native renal biopsies processed at Columbia University. Among the 31 patients, 21 presented with acute renal failure (ARF), were normocalcemic, and had a history of recent colonoscopy preceded by bowel cleansing with oral sodium phosphate solution (OSPS) or Visicol. Because the precipitant was OSPS rather than hypercalcemia, these cases are best termed acute phosphate nephropathy. The cohort of 21 patients with APhN was predominantly female (81.0%) and white (81.0%), with a mean age of 64.0 yr. Sixteen of the 21 patients had a history of hypertension, 14 (87.5%) of whom were receiving an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker. The mean baseline serum creatinine was 1.0 mg/dl, available within 4 mo of colonoscopy in 19 (90.5%) patients. Patients presented with ARF and a mean creatinine of 3.9 mg/dl at a median of 1 mo after colonoscopy. In a few patients, ARF was discovered within 3 d of colonoscopy, at which time hyperphosphatemia was documented. Patients had minimal proteinuria, normocalcemia, and bland urinary sediment. At follow-up (mean 16.7 mo), four patients had gone on to require permanent hemodialysis. The remaining 17 patients all have developed chronic renal insufficiency (mean serum creatinine, 2.4 mg/dl). Acute phosphate nephropathy is an underrecognized cause of acute and chronic renal failure. Potential etiologic factors include inadequate hydration (while receiving OSPS), increased patient age, a history of hypertension, and concurrent use of an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker.
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PMID:Acute phosphate nephropathy following oral sodium phosphate bowel purgative: an underrecognized cause of chronic renal failure. 1619 15

We have shown that renal injury and chronic kidney disease (CKD) directly inhibit skeletal anabolism, and that stimulation of bone formation decreases the serum phosphate. Most recently, these observations were rediscovered in low-density lipoprotein receptor null mice fed high-fat/cholesterol diets, a model of the metabolic syndrome (hypertension, obesity, dyslipidemia, and insulin resistance). We had demonstrated that these mice have vascular calcification (VC) of both the intimal atherosclerotic type and medial type. We have shown that VC is worsened by CKD and ameliorated by bone morphogenetic protein -7 (BMP-7). The finding that high-fat-fed low-density lipoprotein receptor null animals without CKD have hyperphosphatemia led us to examine the skeletons of these mice. We found significant reductions in bone formation rates, associated with increased VC and superimposing CKD results in the adynamic bone disorder (ABD), while VC was worsened and hyperphosphatemia persisted. A pathological link between abnormal bone mineralization and VC through the serum phosphorus was demonstrated by the partial effectiveness of directly reducing the serum phosphate by a phosphate binder that had no skeletal action. BMP-7 treatment corrected the ABD and corrected hyperphosphatemia, compatible with BMP-7-driven stimulation of skeletal phosphate deposition reducing plasma phosphate and thereby removing a major stimulus to VC. Thus, in the metabolic syndrome with CKD, a reduction in bone-forming potential of osteogenic cells leads to ABD producing hyperphosphatemia and VC, processes ameliorated by the skeletal anabolic agent BMP-7, in part through increased bone formation and skeletal deposition of phosphate, and in part through direct actions on vascular smooth muscle cells. We have demonstrated that the processes leading to vascular calcification begin with even mild levels of renal injury before demonstrable hyperphosphatemia, and they are preventable and treatable. Therefore, early intervention in CKD is warranted and may affect mortality of the disease.
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PMID:Connections between vascular calcification and progression of chronic kidney disease: therapeutic alternatives. 1633 68

Vascular calcification is often encountered in advanced atherosclerotic lesions and is a common consequence of aging. Calcification of the coronary arteries has been positively correlated with coronary atherosclerotic plaque burden, increased risk of myocardial infarction, and plaque instability. Chronic kidney disease (CKD) patients have two to five times more coronary artery calcification than healthy age-matched individuals. Vascular calcification is a strong prognostic marker of cardiovascular disease mortality in CKD patients. Vascular calcification has long been considered to be a passive, degenerative, and end-stage process of atherosclerosis and inflammation. However, recent evidence indicates that bone matrix proteins such as osteopontin, matrix Gla protein (MGP), and osteocalcin are expressed in calcified atherosclerotic lesions, and that calcium-regulating hormones such as vitamin D3 and parathyroid hormone-related protein regulate vascular calcification in in vitro vascular calcification models based on cultured aortic smooth muscle cells. These findings suggest that vascular calcification is an actively regulated process similar to osteogenesis, and that bone-associated proteins may be involved in the development of vascular calcification. The pathogenesis of vascular calcification in CKD is not well understood and is almost multifactorial. In CKD patients, several studies have found associations of both traditional risk factors, such as hypertension, hyperlipidemia, and diabetes, and uremic-specific risk factors with vascular calcification. Most patients with progressive CKD develop hyperphosphatemia. An elevated phosphate level is an important risk factor for the development of calcification and cardiovascular mortality in CKD patients. Thus, it is hypothesized that an important regulator of vascular calcification is the level of inorganic phosphate. In order to test this hypothesis, we characterized the response of human smooth muscle cell (HSMC) cultures to inorganic phosphate levels. Our findings indicate that inorganic phosphate directly regulates HSMC calcification through a sodium-dependent phosphate transporter mechanism. After treatment with elevated phosphate, there is a loss of smooth muscle lineage markers, such as alpha-actin and SM-22alpha, and a simultaneous gain of osteogenic markers such as cbfa-1 and osteocalcin. Elevated phosphate may directly stimulate HSMC to undergo phenotypic changes that predispose to calcification, and offer a novel explanation of the phenomenon of vascular calcification under hyperphosphatemic conditions. Furthermore, putative calcification inhibitory molecules have been identified using mouse mutational analyses, including MGP, beta-glucosidase, fetuin-A, and osteoprotegerin. Mutant mice deficient in these molecules present with enhanced cardiovascular calcification, demonstrating that specific molecules are normally important in suppressing vascular calcification. These findings suggest that the balance of inducers, such as phosphate, and inhibitors, such as MGP, fetuin-A, and others, are likely to control whether or not calcification occurs under pathological conditions.
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PMID:Vascular calcification in chronic kidney disease. 1650 29

In two independent and separate studies, we have shown that renal injury and chronic kidney disease (CKD) directly inhibit skeletal anabolism, and that stimulation of bone formation decreased the serum phosphate. In the first study, the serum Ca PO(4), parathyroid hormone (PTH), and calcitriol were maintained normal after renal ablation in mice, and even mild renal injury equivalent to stage 3 CKD decreased bone formation rates. More recently, these observations were rediscovered in low-density lipoprotein receptor null (LDLR-/-) mice fed high-fat/cholesterol diets, a model of the metabolic syndrome (hypertension, obesity, dyslipidemia and insulin resistance). We demonstrated that these mice have vascular calcification (VC) of both the intimal atherosclerotic type and medial calcification. We have also shown that VC is made worse by CKD and ameliorated by bone morphogenetic protein-7 (BMP-7). The finding that high-fat fed LDLR-/- animals with CKD had hyperphosphatemia which was prevented in BMP-7-treated animals lead us to examine the skeletons of these mice. It was found that significant reductions in bone formation rates were associated with high-fat feeding, and superimposing CKD resulted in the adynamic bone disorder (ABD), while VC was made worse. The effect of CKD to decrease skeletal anabolism (decreased bone formation rates and reduced number of bone modelling units) occurred despite secondary hyperparathyroidism. The BMP-7 treatment corrected the ABD and hyperphosphatemia, owing to BMP-7-driven stimulation of skeletal phosphate deposition reducing plasma phosphate and thereby removing a major stimulus to VC. A pathological link between abnormal bone mineralization and VC through the serum phosphorus was demonstrated by the partial effectiveness of directly reducing the serum phosphate by a phosphate binder that had no skeletal action. Thus, in the metabolic syndrome with CKD, a reduction in bone forming potential of osteogenic cells leads to the ABD producing hyperphosphatemia and VC, processes ameliorated by BMP-7, in part through increased bone formation and skeletal deposition of phosphate and in part through direct actions on vascular smooth muscle cells. We have demonstrated that the processes leading to vascular calcification begin with even mild levels of renal injury affecting the skeleton before demonstrable hyperphosphatemia and that they are preventable and treatable. Therefore, early intervention in the skeletal disorder associated with CKD is warranted and may affect mortality of the disease.
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PMID:Function and effect of bone morphogenetic protein-7 in kidney bone and the bone-vascular links in chronic kidney disease. 1688 97

A model of chronic kidney disease (CKD)-induced vascular calcification (VC) that complicates the metabolic syndrome was produced. In this model, the metabolic syndrome is characterized by severe atherosclerotic plaque formation, hypertension, type 2 diabetes, obesity, and hypercholesterolemia, and CKD stimulates calcification of the neointima and tunica media of the aorta. The CKD in this model is associated the adynamic bone disorder form of renal osteodystrophy. The VC of the model is associated with hyperphosphatemia, and control of the serum phosphorus both in this animal model and in humans has been preventive in the development of VC. This article reports studies that demonstrate reduction of established VC by the addition of sevelamer carbonate to the diets of this murine metabolic syndrome model with CKD. Sevelamer, besides normalizing the serum phosphorus, surprisingly, reversed the CKD-induced trabecular osteopenia. Sevelamer therapy increased osteoblast surfaces in the metaphyseal trabeculae of the tibia and femur. It also increased osteoid surfaces and, importantly, bone formation rates. In addition, sevelamer was found to be effective in decreasing serum cholesterol levels. These results suggest that sevelamer may have important actions in decreasing diabetic and uremic vasculopathy and that sevelamer carbonate may be capable of increasing bone formation rates that are suppressed by diabetic nephropathy.
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PMID:Reversal of the adynamic bone disorder and decreased vascular calcification in chronic kidney disease by sevelamer carbonate therapy. 1718 86


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