Uraemic vasculopathy in children with chronic kidney disease: prevention or damage limitation?

Low-density lipoprotein and blood pressure are important risk factors for vasculopathy in children on dialysis: a single center study

INTRODUCTION

We searched for risk factors of cardiovascular assessment among children on dialysis.

METHODS

This is a cross-sectional study of cardiovascular assessment of all patients on dialysis at xxx University Children's Hospital. Pediatric patients between the ages of 6 and 21 who were on hemodialysis and peritoneal dialysis treatment were included in the study. Cardiovascular evaluation included left ventricular mass index (LVMI), pulse wave velocity (PWV), and carotid intima-media thickness (cIMT) measurements.

RESULTS

Nineteen patients were included in this study. The LDL had a correlation with the cIMT z-score, but not to PWVz-score. Binary Logistic regression analysis found that only LDL was significantly associated to increased cIMT.

CONCLUSION

This study reports an association between high LDL and high blood pressure increased cIMT on dialyzed children. Strategies to reduce LDL and blood pressure in dialysis patients may prevent vasculopathy and long-term cardiovascular complications.

The Source Matters-Effects of High Phosphate Intake from Eight Different Sources in Dogs

Elevated serum phosphate concentrations are an established risk factor for cardiovascular disease and mortality in chronic kidney disease in various species. Independent associations of other parameters of phosphorus metabolism, such as phosphorus intake from different sources and serum concentrations of phosphorus, as well as parameters involved in the regulation, such as parathyroid hormone (PTH) or markers of bone turnover, have been studied in less detail. Therefore, the serum kinetics of phosphate, PTH, and the bone resorption marker bone-specific alkaline phosphatase (BAP) were investigated after 18 days of feeding a control diet and diets supplemented with eight different organic and inorganic phosphate sources aiming at 1.8% phosphorus per dry matter and calcium to phosphorus ratio between 1.3 and 1.7 to 1. Eight healthy beagle dogs (f/m, 2-4 years, 12.9 ± 1.4 kg body weight) were available for the trial. Highly significant differences in the serum kinetics of phosphorus, PTH, and BAP with the highest postprandial levels after feeding highly water-soluble sodium and potassium phosphates were found. We conclude that the use of certain inorganic phosphates in pet food is potentially harmful and should be restricted.

Interdialytic weight gain and vasculopathy in children on hemodialysis: a single center study

BACKGROUND

Increased interdialytic weight gain (IDWG) has been associated with poor outcomes in adults, but its impact on hemodialysis vasculopathy in children is unknown.

METHODS

Nineteen patients (age 9 to 19 years old) with a median hemodialysis duration of 10.4 months were enrolled. Cardiovascular evaluation included left ventricular mass index (LVMI), pulse wave velocity (PWV), and carotid intima-media thickness (cIMT) measurements. PWV and cIMT were expressed as z-scores based on reference values in healthy children. Blood pressure (BP) evaluation consisted in a 24-h ambulatory BP monitoring. Mean IDGW and residual urine output during the 6 months prior to cardiovascular examination were calculated.

RESULTS

Increased cIMT, LVMI, and PWV was observed in 11 (57.9%), 7 (36.8%), and 5 (26.3%) patients respectively, while BP was normal in all patients. Median IDWG was 3.5% (1.8-6.7). Residual urine output and BP status did not significantly differ between patients with IDWG ≥ or < 4%. After linear regression, IDWG was correlated to cIMT z-score (r² = 0.485, p = 0.001), but not to PWV z-score (r² = 0.04, p = 0.415) and LVMI (r² = 0.092, p = 0.206). After univariate logistic regression, IDWG ≥ 4% was significantly associated to increased cIMT (above 1.65 SDS) (odds ratio 12.25, 95% confidence interval 1.08-138.988). The trend toward an increased cIMT with IDWG ≥ 4% was observed in both patients with short and long dialysis vintage.

CONCLUSIONS

High IDWG is associated with increased cIMT in hemodialyzed children independently of BP control and dialysis vintage. This observation reinforces the importance of interventions to avoid IDWG in hemodialyzed children.

Why are kids with lupus at an increased risk of cardiovascular disease?

Juvenile-onset systemic lupus erythematosus (SLE) is an aggressive multisystem autoimmune disease. Despite improvements in outcomes for adult patients, children with SLE continue to have a lower life expectancy than adults with SLE, with more aggressive disease, a higher incidence of lupus nephritis and there is an emerging awareness of their increased risk of cardiovascular disease (CVD). In this review, we discuss the evidence for an increased risk of CVD in SLE, its pathogenesis, and the clinical approach to its management.

Nocturnal intermittent hemodialysis

Preemptive renal transplantation is the method of choice for end stage renal disease in childhood and adolescence. However, without preemptive transplantation, waiting time for kidney transplantation might exceed several years. The poor quality of life and the extremely high morbidity and mortality rates of dialysis patients have led to the development of intensified hemodialysis programs in which the modes of dialysis (short daily, nocturnal intermittent or daily nocturnal) are different. Such programs have been shown to significantly improve several uremia-associated parameters, such as blood pressure, phosphate control, anemia and growth retardation, in both adult and pediatric (children and adolescents) patients and lead to a reduction in medications, including phosphate binders, erythropoietin and antihypertensive agents. Fluid limitations and dietary restrictions can also be lifted. With respect to psychosocial rehabilitation and quality of life, nocturnal intermittent dialysis programs provide a reasonable compromise of all forms of intensified programs. Experiences and practical approaches of our own in-center nocturnal intermittent hemodialysis program in the light of the recent publications are described in this review.

Hemodiafiltration in a pediatric nocturnal dialysis program

BACKGROUND

To overcome the deleterious consequences of conventional dialysis, intensified dialysis programs have been developed and their feasibility and beneficial effects in children demonstrated. To investigate whether such a program can be further improved, we implemented hemodialfiltration within an established pediatric in-center, nocturnal hemodialysis program.

METHODS

After being started on conventional hemodialysis (HD), seven patients were switched to intermittent nocturnal hemodialysis (NHD) for 3 months, then to intermittent nocturnal online-hemodiafiltration (NHDF) for a further 3 months and finally back to NHD. Uremia-associated parameters, predialytic blood pressure, intradialytic events, protein catabolic rate and levels of albumin, vitamins and trace elements were investigated. Dialysis-related medication and dietary restrictions were also registered.

RESULTS

Phosphate and intact parathyroid hormone levels were reduced after the switch from HD to NHD and NHDF. Dialysis dose (Kt/V) was increased in patients on NHD and NHDF; however, Kt/V was significantly higher with NHDF than NHD. Blood pressure was significantly reduced in patients on NHD and NHDF despite the reduction in antihypertensive medication; albumin levels were significantly higher on NHD and NHDF, indicating improved nutritional status; protein catabolic rate was also increased. Vitamins and trace elements remained unchanged. All dietary restrictions could be lifted in patients on NHD and NHDF.

CONCLUSIONS

The introduction of a nocturnal dialysis program to an existing intensified HD program significantly improved the uremia-associated parameters, nutrition and hemodynamic stability of our seven patients. At least during our observational period, hemodiafiltration was able to further improve the existing HD program by increasing the Kt/v.

Intensified hemodialysis in adults, and in children and adolescents

BACKGROUND

There are now almost 70 000 dialysis patients in Germany. Conventional hemodialysis does not adequately compensate for malnutrition, arterial hypertension, renal osteopathy, and diminished performance ability. Various strategies for intensified hemodialysis have been implemented in an attempt to lower the considerable morbidity and mortality of end-stage renal failure.

METHOD

We selectively review the literature on intensified dialysis in adults, children, and adolescents.

RESULTS

In a randomized, controlled trial (RCT), a group of patients undergoing conventional dialysis was compared to a group undergoing brief, daily dialysis. Daily dialysis significantly improved the combined endpoint of left-ventricular hypertrophy or death (hazard ratio [HR] 0.61). In contrast, another, retrospective study found daily dialysis to be associated with higher mortality (15.6 vs. 10.9 deaths, HR 1.6). A prospective case-control study found nocturnal intermittent hemodialysis to be associated with lower mortality than conventional dialysis (1.77 vs. 6.23 per 100 patient-years); this result was confirmed in a further, retrospective study. An RCT on nocturnal dialysis performed every night revealed a significant regression of left-ventricular mass, yet the patients' quality of life improved only in individual domains specifically related to renal function. Small-scale studies of intensified hemodialysis in children and adolescents have found that it leads to a higher growth rate and weight gain.

CONCLUSION

Intensified hemodialysis techniques improve arterial blood pressure, uremia-associated variables, and psychosocial variables. They also lower the necessary doses of antihypertensive drugs and phosphate binders. Dietary restrictions need not be as stringent. Further prospective trials are needed for a reliable assessment of the effect of intensified hemodialysis on mortality and quality of life.

Cardiovascular changes during chronic hypertensive states

It is well established that elevated blood pressure constitutes a major risk factor for coronary heart disease, arrythmias, heart failure, cerebrovascular disease, peripheral artery disease and renal failure. Blood pressure level and the duration of arterial hypertension (HTN) impact target organ damage. Many studies in adults have demonstrated the role of antihypertensive therapy in preventing cardiovascular (CV) events. The so-called hard end-points, such as death, myocardial infarction (MI) or stroke, are rarely seen in children, but intermediate target organ damage, including left ventricular hypertrophy, increased intima-media thickness and microalbuminuria, is already detectable during childhood. The goal of antihypertensive treatment is to reduce the global risk of CV events. In the adult population stratification of CV risk is based on blood pressure level, risk factors, subclinical target organ damage and established CV and kidney disease. Increased CV risk begins early in the course of kidney disease, and CV diseases are the most frequent cause of morbidity and mortality in patients with chronic kidney disease (CKD). Children with CKD are especially prone to the long-term effects of CV risk factors, which result in high morbidity and mortality in young adults. To improve the outcome, pediatric and adult CKD patients require nephro- and cardioprotection.

Malnutrition and its association with inflammation and vascular disease in children on maintenance dialysis

BACKGROUND

Malnutrition is associated with both inflammation and atherosclerotic cardiovascular disease in adults with chronic kidney disease. We studied the prevalence of malnutrition and its possible associations with inflammation and vascular disease in children on chronic dialysis.

METHODS

Thirty-three patients on maintenance dialysis (18 peritoneal dialysis, 15 hemodialysis) and 19 age- and gender- matched healthy controls were studied. Nutritional status was assessed by anthropometric measurements including body mass index (BMI), upper arm measurements, multifrequency bioimpedance analysis (BIA) and serum levels of albumin, prealbumin, and cholesterol. Inflammation was assessed by serum levels of C-reactive protein (CRP), interleukin (IL)-6, and tumor necrosis factor (TNF)-alpha. The carotid artery intima thickness (cIMT) was measured to assess vascular disease.

RESULTS

Compared with healthy children, patients had lower anthropometric measurements (P < 0.05) and serum albumin level (P < 0.001), and higher CRP and TNF-alpha (P = 0.030 and P = 0.007, respectively), and higher cIMT-SDS (P < 0.001). Malnutrition was present in 8 (24%) and lower BIA-based fat mass was independently associated with higher IL-6 levels (P = 0.035). An increased cIMT was present in 16 (48.5%); however, there was no difference in cIMT-SDS between patients with and without malnutrition. Carotid IMT did not show any association with nutritional indices; but positively correlated with serum IL-6 (P = 0.037), CRP (P = 0.012), and iPTH (P = 0.009), and independently associated with only iPTH (P = 0.018).

CONCLUSIONS

Children on dialysis are at an increased risk of malnutrition, inflammation, and vascular disease. Although each of these three conditions exists, there is no interaction among them all. We postulate that the malnutrition-inflammation-atherosclerosis (MIA) complex might not exist in pediatric dialysis patients.

Product of serum calcium and phosphorus (Ca × PO4) as predictor of cardiovascular disease risk in predialysis patients

OBJECTIVES

The mortality rate of chronic kidney disease (CKD) patients is very high due to cardiovascular diseases (CVD) which cannot be fully justified by traditional CVD markers. Since, mineral bone disorder is common in CKD, product of serum calcium and phosphorus (Ca × PO4) can be a predictor of future CVD. So, our study aims to assess the utility of higher Ca × PO4 in prediction of CVD risk in predialysis CKD patients.

DESIGN AND METHODS

150 CKD patients defined by NKF-KDOQI guideline not undergoing dialysis were recruited. Anthropometric and electrocardiographic parameters were recorded. We evaluated CVD risk by: i) Biochemical CVD markers, ii) NCEP ATP III guideline postulated risk factors and iii) Framingham risk scores.

RESULTS

Higher Ca × PO4 is associated with presence of Left Ventricular Hypertrophy, oxidative stress, microinflammation, hyperhomocysteinemia, hypercholesterolemia, hypertriglyceridemia and increased LDLc. Compared to cases with Ca × PO4 <55 mg2/dL2, cases with ≥55 mg2/dL2 had relative risk (RR) of 1.82 (95% CI 1.25-2.64) for CVD, 3.24 (95% CI 2.37-4.41) for stroke and 2.43 (95% CI 1.37-4.31) for coronary heart disease (CHD). Moreover, compared to lowest quartile of Ca x PO4, the highest quartile group had RR of 2.13 (95% CI 1.06-4.28) for CVD, 2.61(95% CI 1.80-3.75) for stroke and 2.84 (95% CI 1.15-7.0) for CHD.

CONCLUSION

In predialysis patients, higher Ca × PO4 is independent predictor of CVD risk.

Cardiovascular risk assessment in children with chronic kidney disease

Chronic kidney disease (CKD) is a major factor contributing to cardiovascular (CV) morbidity and mortality with the highest risk in patients on dialysis. An estimation of CV risk is important not only to identify potential modifiable risk factors but also to evaluate the effect of treatments aimed to reduce the risk. Non-invasive methods of measuring vascular changes and circulating biomarkers are available to assess the presence and severity of cardiovascular damage. These include measures of structural (carotid intima-media thickness and coronary artery calcification score) and functional (aortic pulse wave velocity, 24-h ambulatory blood pressure monitoring, ambulatory arterial stiffness index, heart rate variability and flow-mediated dilatation) changes in the vessel wall. In addition, a number of circulating biomarkers of vascular damage and its progression have been studied. Many of these tests are well validated as surrogate markers of future cardiovascular events and death in adult CKD patients, but need technical adaptation, standardization and validation for use in children. With our current state of knowledge, these are best reserved for research studies and scarce clinical resources may be better utilized for preventative strategies to reduce the modifiable risk factors for calcification from early CKD stages.

Phosphate is a vascular toxin

Elevated phosphate (P) levels are seen in advanced renal failure and, together with dysregulated calcium, parathyroid hormone and vitamin D levels, contribute to the complex of chronic kidney disease-mineral and bone disease (CKD-MBD). Converging evidence from in vitro, clinical and epidemiological studies suggest that increased P is associated with vascular calcification and mortality. When vessels are exposed to high P conditions in vitro, they develop apoptosis, convert to bone-like cells and develop extensive calcification. Clinical studies in children on dialysis show that high P is associated with increased vessel wall thickness, arterial stiffness and coronary calcification. Epidemiological studies in adult dialysis patients demonstrate a significant and independent association between raised P and mortality. Importantly, raised P is associated with cardiovascular changes even in pre-dialysis CKD, and also in subjects with normal renal function but high P. All P binders can effectively reduce serum P, and this decrease is linked to improved survival. Raised serum P triggers the release of fibroblast growth factor 23 (FGF-23), which has the beneficial effect of increasing P excretion in early CKD, but is increased several 1,000-fold in dialysis, and may be an independent cardiovascular risk factor. Both FGF-23 and its co-receptor Klotho may have direct effects on the vasculature leading to calcification. Fascinatingly, disturbances in FGF-23-Klotho and raised P have also been associated with premature aging. These data suggest that high P levels have adverse vascular effects and that maintaining the serum P levels in the normal range reduces cardiovascular risk and mortality.

Intima media thickness in children undergoing dialysis

BACKGROUND

Uremic vasculopathy, including vascular calcification, increases the risk for cardiovascular disease and mortality in chronic kidney disease (CKD) patients. We have investigated the prevalence and factors associated with vasculopathy in children undergoing peritoneal dialysis (PD) or hemodialysis (HD) in a single center.

METHODS

Common carotid intima media thickness (cIMT) and its relation with demographics, biochemical parameters and medication was analyzed in 60 patients (mean age 12.9 ± 3.4 years; 27 girls) treated with PD (n = 31) or HD (n = 29) for 34 ± 34 months. Patients were divided into two groups: normal cIMT and increased cIMT.

RESULTS

Mean levels of calcium, phosphate and calcium/phosphate product were in the normal range, the but parathyroid hormone level, 729 ± 670 pg/mL, was higher than the National Kidney Foundation Kidney Disease Outcome Quality Iniative (K/DOQI) recommendations. Twenty-nine patients had increased cIMT, which was associated with time on dialysis of >2 years, hypercalcemia, higher daily dose of calcitriol and HD (vs. PD). In the multivariate analysis, accounting for time on dialysis, HD persisted as a risk for increased cIMT.

CONCLUSIONS

The prevalence of increased cIMT in children on dialysis is similar to that reported in adults with CKD and increased with time on dialysis. HD was associated with increased cIMT, independently of time on dialysis; however, the results should be interpreted with caution due to the possible impact of confounding factors. These results underline the need to monitor and, if possible, prevent and treat increased cIMT in children on dialysis.

Glucose intolerance: is it a risk factor for cardiovascular disease in children with chronic kidney disease?

A total of 66 children and adolescents with chronic kidney disease (CKD) (20 pre-dialysis patients and 46 chronic dialysis patients) were evaluated to address the prevalence of abnormalities in glucose and insulin metabolism and their association with cardiovascular disease. Glucose intolerance was assessed using an oral glucose tolerance test; insulin resistance was estimated by the homeostasis model assessment of insulin resistance (HOMA-IR). Carotid artery intima-media thickness (IMT) and left ventricular hypertrophy (LVH) were examined as early markers of cardiovascular disease. Thirty-four patients (7 pre-dialysis, 27 dialysis) exhibited an abnormal glucose tolerance; however, ten patients (7 pre-dialysis, 3 dialysis) were insulin-resistant. Height-specific standard deviation scores of carotid artery IMT were above normal in three of the pre-dialysis patients (15%) and in 34 of the dialysis patients (74%). LVH was present in seven pre-dialysis (35%) and 34 dialysis patients (74%). In addition, two of the pre-dialysis patients (10%) and 18 of the dialysis patients (39%) had severe LVH. The prevalence of both increased carotid artery IMT and LVH were similar in patients with or without glucose intolerance in both groups, but severe LVH was more prevalent in pre-dialysis patients with glucose intolerance (p = 0.042). The multivariate analyses showed that neither carotid artery IMT nor LVM index was predicted by serum glucose levels or HOMA-IR. In conclusion, children with CKD are at a high risk of glucose intolerance and also have a greater risk of subclinical cardiovascular disease (CVD). However, the presence of glucose intolerance does not appear to be an independent risk factor for increased carotid artery IMT or LVH.

Ergocalciferol supplementation in children with CKD delays the onset of secondary hyperparathyroidism: a randomized trial

BACKGROUND AND OBJECTIVES

Vitamin D deficiency is an important contributor to the development of hyperparathyroidism and is independently associated with cardiovascular and bone disease. The hypothesis was that nutritional vitamin D (ergocalciferol) supplementation in children with CKD stages 2-4 delays the onset of secondary hyperparathyroidism.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A randomized, double-blinded, placebo-controlled study in children with CKD2-4 who had 25-hydroxyvitamin D [25(OH)D] deficiency was conducted. Ergocalciferol (or a matched placebo) was given daily as per Kidney Disease Outcomes Quality Initiative guidelines. The primary endpoint was the time to development of hyperparathyroidism.

RESULTS

Seventy-two children were screened. Forty-seven children were 25(OH)D-deficient and randomly assigned to receive ergocalciferol or placebo. Twenty children in each arm completed the study; median follow-up was 12 months. Groups were well matched for age, race, estimated GFR, and season when recruited. Nine of 20 children on placebo and 3 of 20 children on ergocalciferol developed hyperparathyroidism (odds ratio, 4.64; 95% confidence interval, 1.02-21.00). The time to development of hyperparathyroidism was significantly longer with ergocalciferol treatment compared with placebo (hazard ratio, 0.30; 95% confidence interval, 0.09-0.93, P=0.05). With ergocalciferol treatment, normal 25(OH)D levels were achieved in all 8 children with CKD2, 8 of 11 children with CKD3, but not in the single patient with CKD4. There were no ergocalciferol-related adverse events. 25(OH)D levels >100 nmol/L were required to achieve normal levels of 1,25-dihydroxyvitamin D.

CONCLUSIONS

Ergocalciferol is an effective treatment that delays the development of secondary hyperparathyroidism in children with CKD2-3.

Is fiber-type composition related to daily jaw muscle activity during postnatal development?

AIM

Muscles containing large numbers of slow-contracting fibers are generally more active than muscles largely composed of fast fibers. This relationship between muscle activity and phenotype suggests that (1) changes in fiber-type composition during postnatal development are accompanied by changes in daily activity and (2) individual variations in fiber-type composition are related to similar variations in daily muscle activity.

METHODS

The masseter and digastric muscles of 23 New Zealand White rabbits (young, juvenile and adult) were examined for their phenotype (myosin heavy chain content) and their daily activity (total daily number of activity bursts).

RESULTS

During development, the masseter showed a strong increase in the number of fast-type fibers compared to the number of slow-type fibers. During development, also the number of powerful bursts in the masseter increased. The digastric showed no significant changes in fiber types or burst numbers. Within each muscle, across individual animals, no significant correlations (R < 0.70) were found between any of the fiber types and daily burst numbers in any of the age groups.

CONCLUSIONS

The results suggest that activity-related influences are of relatively minor importance during development and that other factors are dominant in determining fiber-type composition.