Vascular calcifications as a footprint of increased calcium load and chronic inflammation in uremic patients: a need for a neutral calcium balance during hemodialysis?

Hyperphosphatemia in Dialysis Patients: The Therapeutic Role of Lanthanum Carbonate

Phosphate overload is a dramatic consequence in end-stage renal disease (ESRD) patients. Recent studies have well documented that abnormalities in mineral and bone metabolism in these patients are associated with increased cardiovascular morbidity and mortality. Elevated serum phosphate and calcium-phosphate product levels play an important role in the pathogenesis of secondary hyperparathyroidism and extra-skeletal calcification in dialysis patients. Furthermore, inorganic phosphate may cause vascular calcification directly through a real “ossification” of the tunica media in the vasculature of ESRD patients.

The “classical” treatment of secondary hyperparathyroidism and hyperphosphatemia in ESRD patients consists of either calcium- or aluminum-based phosphate binders and calcitriol administration. Unfortunately, this “old generation” therapy is not free of complications. This review paper suggests that new calcium- and aluminum-free phosphate binders, such as lanthanum carbonate, can be used to treat hyperphosphatemia and secondary hyperparathyroidism in ESRD patients.

NF-κB-mediated inflammation correlates with calcium overload under arsenic trioxide-induced myocardial damage in Gallus gallus

Arsenic is a known environmental pollutant and highly hazardous toxin to human health. Due to the biological accumulation, arsenic produces a variety of cardiovascular diseases. However, the exact mechanism is still unclear. Here, our objective was to evaluate myocardial damage and determine the potential mechanism under arsenic exposure in chickens. Arsenic trioxide (As₂O₃) (1.25 mg/kg BW, corresponding 15 mg/kg feed) was administered as basal diet to male Hy-line chickens (one-day-old) for 4, 8 and 12 weeks. The results showed that As₂O₃-induced histological and ultrastructural damage in heart accompanied with significantly Ca²⁺ overload and increased the activities of myocardial enzymes. Moreover, As₂O₃ exposure significantly increased (P < 0.05) the mRNA levels of ITPR3, PMCA, TRPC1, TRPC3, STIM1, ORAI1 and pro-inflammatory genes, while the mRNA levels of ITPR1, ITPR2, RyR1, RyR3, SERCA, SLC8A1, CACNA1S and interleukin-10 were decreased (P < 0.05) by As₂O₃ exposure at 4, 8 and 12 weeks as compared with the corresponding control group. Western blot results showed that As₂O₃ exposure decreased the expression of SERCA and SLC8A1 protein, while the expression of TNF-α, NF-κB, iNOS and PMCA1 increased compared with the corresponding control group. Additionally, correlation analysis and protein-protein interaction prediction shown that NF-κB-mediated inflammatory response have a function correlation with calcium (Ca) regulation-related genes. In conclusion, this study indicated that As₂O₃-induced inflammatory response might dependent on Ca overload in myocardial damage of chickens. Our work has implications for the development of potential therapeutic approaches by resisting Ca overload for arsenic-induced myocardial damage.

Effects of Lipid Abnormalities on Arteriosclerosis and Hemostatic Markers in Patients under Hemodialysis

Vascular events caused by arteriosclerosis are the major cause of death in patients under hemodialysis (HD). Arteriosclerosis is associated with lipoprotein abnormalities such as increased serum levels of low-density lipoprotein (LDL), especially of modified LDL (M-LDL) and oxidized LDL (Ox-LDL). We examined the relationship between markers of arteriosclerosis, hemostasis, and lipid metabolism in patients with chronic renal failure, hyperlipidemia, and healthy volunteers. In patients under HD, the serum levels of total cholesterol, LDL, and triglyceride (TG) were decreased, but the serum levels of M-LDL were increased compared to HL and healthy volunteers. In patients with CRF, the serum levels of OxLDL in patients under HD were lower than in those under continuous ambulatory peritoneal dialysis or conservative therapy. The plasma levels of antithrombin and protein C were significantly lower and the plasma levels of thrombomodulin were significantly higher in patients under HD compared to those under conservative therapy. These data show that patients under HD were more in hypercoagulable state than those under conservative therapy. Among patients under HD, only the plasma levels of von Willebrand factor were significantly increased in patients with more than 30 U/L of Ox-LDL compared to those with less than 30 U/L of Ox-LDL. There was no significant difference in the tests of arteriosclerosis among M-LDL values and OxLDL values. These findings suggest that abnormalities of lipid are not the main risk factor for arteriosclerosis disease in patients under HD.

The role of serum magnesium and calcium on the association between adiponectin levels and all-cause mortality in end-stage renal disease patients

BACKGROUND

Adiponectin (ADPN) is the most abundant adipocyte-specific cytokine that plays an important role in energy homeostasis by regulating lipid and glucose metabolism. Studies of the impact of ADPN on clinical outcomes have yielded contradictory results so far. Here, we examined the association of ADPN with serum magnesium (s-Mg) and calcium (s-Ca) levels and explored the possibility whether these two factors could modify the relationship between ADPN and all-cause mortality in patients with end-stage renal disease.

METHODOLOGY/PRINCIPAL FINDINGS

After baseline assessment, 47 hemodialysis and 27 peritoneal dialysis patients were followed- up for a median period of 50 months. S-Mg and s-Ca levels emerged as positive and negative predictors of ADPN levels, respectively. During the follow-up period 18 deaths occurred. There was a significant 4% increased risk for all-cause mortality for each 1-µg/ml increment of ADPN (crude HR, 1.04; 95% CI, 1.01-1.07), even after adjustment for s-Mg and s-Ca levels, dialysis mode, age, albumin and C-reactive protein. Cox analysis stratified by s-Mg levels (below and above the median value of 2.45 mg/dl) and s-Ca levels (below and above the median value of 9.3 mg/dl), revealed ADPN as an independent predictor of total mortality only in the low s-Mg and high s-Ca groups. Furthermore, low s-Mg and high s-Ca levels were independently associated with malnutrition, inflammation, arterial stiffening and risk of death.

CONCLUSIONS/SIGNIFICANCE

The predictive value of ADPN in all-cause mortality in end-stage renal disease patients appears to be critically dependent on s-Mg and s-Ca levels. Conversely, s-Mg and s-Ca may impact on clinical outcomes by directly modifying the ADPN's bioactivity.

Is there any relationship between serum levels of interleukin-10 and atherosclerosis in hemodialysis patients?

OBJECTIVE

Cardiovascular complications due to atherosclerosis (AS) are the major cause of mortality in hemodialysis (HD) patients. Inflammation may play an important role in the development of AS. Several studies have demonstrated an association between AS and acute-phase proteins and cytokines in the general population and in HD patients. Interleukin-10 (IL-10) is an anti-inflammatory cytokine. The aim of this study was to compare serum levels of inflammatory and anti-inflammatory indicators in HD patients according to the presence or absence of AS.

MATERIAL AND METHODS

A total of 33 HD patients were studied. AS was defined as the presence of plaques as detected by Doppler ultrasonography. The patients were subgrouped according to the presence or absence of plaques. Serum levels of IL-1, -2, -6 and -10, C-reactive protein (CRP) and tumor necrosis factor-alpha (TNF-alpha) were measured. Risk factors for AS, such as age, gender, hypertension, hyperlipidemia and duration of HD, were also evaluated.

RESULTS

Patients with AS had significantly higher high sensitivity (hs)-CRP and lower IL-10 levels. Blood pressure was also elevated in patients with AS. There was an inverse correlation between CRP and IL-10 levels in patients with AS.

CONCLUSION

Patients with AS undergoing HD had low serum levels of the anti-inflammatory cytokine IL-10 and high serum levels of hs-CRP. These results may suggest that limitation of the anti-inflammatory response in atherosclerotic uremic patients is a triggering or contributory factor for AS.

Review of dialysate calcium concentration in hemodialysis

The dialysate calcium (Ca) concentration for hemodialysis (HD) patients can be adjusted to manage more optimally the body's Ca and phosphate balance, and thus improve bone metabolism as well as reduce accelerated arteriosclerosis and cardiovascular mortality. The appropriate dialysate Ca concentration allowing this balance should be prescribed to each individual patient depending on a multitude of variable factors relating to Ca load. A lower dialysate Ca concentration of 1.25 to 1.3 mmol/L will permit the use of vitamin D supplements and Ca-based phosphate binders in clinical practice, with much less risk of Ca loading and resultant hypercalcemia and calcification. Low Ca baths are useful in the setting of adynamic bone disease where an increase in bone turnover is required. However, low Ca levels in the dialysate may also predispose to cardiac arrhythmias and hemodynamically unstable dialysis sessions with intradialytic hypotension. Higher Ca dialysate is useful to sustain normal serum Ca levels where patients are not taking Ca-based binders or if Ca supplements are not able to normalize serum levels. Suppression of hyperparathyroidism is also effective with dialysate Ca of 1.75 mmol/L, but hypercalcemia, metastatic calcification, and oversuppression of parathyroid hormone are risks. Dialysate Ca of 1.5 mmol/L may be a compromise between bone protection and reduction in cardiovascular risk for conventional HD and is a common concentration used throughout the world. The increase in longer, more frequent dialysis such as short-daily and nocturnal HD, however, provides another challenge with regard to optimal dialysate Ca levels and higher levels of 1.75 mmol/L are probably indicated in this setting. Difficulties in determining the ideal dialysate Ca occur because of the complex pathophysiology of bone and mineral metabolism in HD patients and there needs to be a balance between dialysis prescription and other treatment modalities. To optimize management of the abnormal Ca balance, other aspects of this disorder need to be more fully clarified and, with evolving medications for phosphate control and treatment of secondary hyperparathyroidism, as well as the emergence of a multitude of different HD regimes, further studies are required to make definitive recommendations. At present, we need to maintain flexibility with HD treatments and so dialysate Ca needs to be individualized to meet the specific requirements of patients by optimizing management of renal bone disease and simultaneously reducing metastatic calcification and cardiovascular disease.

Application of NKF-K/DOQI Clinical Practice Guidelines for Bone Metabolism and Disease: changes of clinical practices and their effects on outcomes and quality standards in three haemodialysis units

BACKGROUND

The K/DOQI Clinical Practice Guidelines for Bone Metabolism and Disease in Chronic Kidney Disease was published in October 2003. The objective of this study was to analyse the effect of the application of those guidelines on clinical practices and on the achievement of bone disease targets and quality standards.

METHODS

We included in the study 342 patients dialysed in our three HD units during 2003 and 2004. Starting October 2003, the K-DOQI recommendations were introduced into practice. Parathyroid hormone (PTH) was measured every 3 months and the serum Ca and P levels, monthly. In patients whose medications were modified, PTH was measured monthly and Ca and P levels, weekly or biweekly.

RESULTS

The following are the main findings for 2004 (post-K/DOQI): an increased use of dialysates with a Ca concentration of 2.5 mEq/l (27.2-50.9%, P<0.001) and a reduced use of a dialysate calcium of 3.0 mEq/l (44.6-39.6%, P: NS) and 3.5 mEq/l (28-9.4%, P<0.001); a reduced use of calcium-based phosphate binders (891.9-565.5 mg Ca/day, P<0.001) and increased use of sevelamer hydrochloride (800 mg) (from 4.86 to 7.51 mg, tablets/day, P<0.001) lower serum Ca levels (9.7-9.4 mg/dl, P<0.01), and higher intact PTH levels (201.4-311.8 pg/ml, P<0.001), without changes in serum P levels; an increased proportion of patients with serum Ca levels within the K/DOQI target range (38.7-46.6%, P<0.01), resulting mainly from the reduced percentage of patients with hypercalcaemia (55-44.4%, P<0.01); a decreased proportion of patients with PTH<150 pg/ml (53.8-31.4%, P<0.001) but an increased proportion of patients with PTH>300 pg/ml, with no change in the proportion of patients with PTHs within the K/DOQI target range. Phosphorus levels and targets did not show significant differences between 2003 and 2004 (56.9-56.2%, P: NS).

CONCLUSIONS

The only way to ensure that K/DOQI guidelines actually improve medical outcomes is to emphasize implementation strategies and also the scientific evaluation of their effectiveness in clinical settings. In spite of the application of the K-DOQI recommendations, a large proportion of our patients stayed outside the proposed targets, which points to the need for more effective therapeutic options.

Cardiovascular disease and chronic kidney disease: insights and an update

Despite the high prevalence and significant morbidity and mortality rates of chronic kidney disease (CKD) related to cardiovascular disease, it remains vastly understudied. Most of the current practice recommendations come from small under-powered prospective studies, retrospective reviews, and assuming patients with CKD will similarly benefit from medications and treatments as patients with normal renal function. In addition, because of the previous lack of a consistent definition of CKD and how to measure renal function, definitions of the degree of renal dysfunction have varied widely and compounded the confusion of these data. Remarkably, despite patients with CKD representing the group at highest risk from cardiovascular complications, even greater than patients with diabetes mellitus, there has been a systematic exclusion of patients with CKD from therapeutic trials. This review outlines our current understanding of CKD as a cardiovascular risk factor, treatment options, and the future directions that are needed to treat cardiovascular disease in patients with CKD.

Which parameter is more influential on the development of arteriosclerosis in hemodialysis patients?

Arteriosclerosis is characterized by stiffening of arteries. The incremental elastic modulus (Einc) measurement is a good marker of arterial wall stiffness. Metabolic, inflammatory and hemodynamic alterations cause structural changes and vascular complications in end stage renal disease. The aim of the present study was to evaluate the factors that may affect the development of arteriosclerosis by measurement of Einc in hemodialysis (HD) patients. Thirty-two patients (16 men; 16 female) on chronic HD with a mean age of 42.2 +/- 19.3 (range: 15-80) were included in the study. The carotid Einc was measured to determine arteriosclerosis by high-resolution echo-tracking system (Acuson Aspen, Acuson Corp., Mountain View, California, USA). Einc measurement was calculated from transcutaneous measurements of common carotid arterial (CCA) internal diameter and wall thickness and carotid pulse pressure. Common carotid compliance and distensibility were determined from changes in carotid artery diameter during systole and simultaneously measured carotid pulse pressure. Common carotid artery stuffiness (Einc) was influenced by age, systolic blood pressure (SBP), pulse pressure (PP), calcium (Ca) and alkaline phosphatase (ALP). The distensibility of CCA was correlated with age, SBP, diastolic blood pressure (DBP), PP, Ca, ALP, and parathormone (PTH). The inflammatory parameter, hs-CRP, was increased with Einc. The mean Einc measurement was found significantly increased in patient receiving vitamin D. In conclusion, the stiffening of carotid artery in HD patients is related not only to hemodynamic changes (increased SBP, PP) but also to metabolic (increased Ca) and to inflammation (increased hs-CRP). Carotid Einc is accepted independent risk factor for cardiovascular mortality. Because of the positive correlation between Einc and serum Ca, vitamin D and Ca containing phosphorus (P) binders should be used carefully.