Relationship of leptin and insulin-like growth factor I to nutritional status in hemodialyzed children

Associations between insulin-like growth factor-1 standard deviation score and overall nutritional parameters in patients with maintenance hemodialysis: a cross-sectional study

BACKGROUND

This study investigated the association between insulin-like growth factor-1 and nutritional status indicators in patients undergoing maintenance hemodialysis (MHD).

METHODS

Patients undergoing MHD for > 3 months were included in this single-center cross-sectional study in March 2021. Clinical, demographic, and body mass data and blood samples were collected before the hemodialysis sessions. Serum insulin-like growth factor-1 (IGF-1) levels were measured using a radioimmunoassay, and serum IGF-1 standard deviation score (SDS) was calculated for MHD patients according to age and sex. The nutritional status of patients was assessed using serum albumin, serum prealbumin, handgrip strength, pinching strength, upper arm muscle circumference, lean body mass, phase angle, seven-point subjective global assessment (SGA) score, and geriatric nutritional risk index (GNRI). The patients were divided into groups according to tertiles of serum IGF-1 SDS levels. Spearman correlation analyses and univariate and multivariate binary logistic regression analyses were used to determine the association between serum IGF-1 SDS and nutritional status parameters.

RESULTS

A total of 155 MHD patients (male: female = 90:65) were enrolled in the study, with a median dialysis vintage of 28.0 (11.0, 55.0) months, and an average age of 66 (65.5 ± 13.0) years. The median of IGF-1 SDS was - 0.1 (- 0.6 to 0.6). Compared to patients with higher IGF-1 SDSs, patients with lower IGF-1 SDSs had lower levels of serum ceruloplasmin (341.0 [287.5, 416.0] vs 395.0 [327.0, 451.0] vs 409.0 [349.5, 507.5], p = 0.002), serum albumin (34.7 ± 3.0 vs 37.0 ± 3.1 vs 37.8 ± 2.6, p < 0.001), serum prealbumin (270.3 [233.7, 327.8] vs 326.0 [279.3, 355.6] vs 363.0 [324.2, 398.2], p < 0.001), handgrip strength (13.8 [10.0, 20.7] vs 17.7 [10.7, 22.5] vs 23.3 [16.6, 27.8], p < 0.001), pinch strength (4.6 [3.9, 6.0] vs 4.9 (3.9, 6.9) vs 6.5 [4.7, 8.7], p = 0.002), phase angle (3.3 [3.0, 3.8] vs 3.9 [3.4, 4.7] vs 4.3 [3.6, 5.2, p < 0.001), modified Creatinine Index (83.1 ± 19.7 vs 93.1 ± 23.4 vs 113.9 ± 24.3, p < 0.001), intracellular water (14.5 ± 4.4 vs 16.1 ± 4.9 vs 16.9 ± 4.4, p = 0.031), higher extracellular water (26.9 ± 5.8 vs 25.7 ± 5.5 vs 25.1 ± 3.1, p = 0.042), and higher malnutrition risk as defined by GNRI (49.0% vs 15.7% vs 11.5%, p < 0.001) and SGA (53.9% vs 23.5% vs 7.7%, p < 0.001).

CONCLUSIONS

Lower IGF-1 SDSs are independently associated with higher malnutrition risk in patients with MHD.

Muscle Wasting in Chronic Kidney Disease: Mechanism and Clinical Implications—A Narrative Review

Muscle wasting, known to develop in patients with chronic kidney disease (CKD), is a deleterious consequence of numerous complications associated with deteriorated renal function. Muscle wasting in CKD mainly involves dysregulated muscle protein metabolism and impaired muscle cell regeneration. In this narrative review, we discuss the cardinal role of the insulin-like growth factor 1 and myostatin signaling pathways, which have been extensively investigated using animal and human studies, as well as the emerging concepts in microRNA- and gut microbiota-mediated regulation of muscle mass and myogenesis. To ameliorate muscle loss, therapeutic strategies, including nutritional support, exercise programs, pharmacological interventions, and physical modalities, are being increasingly developed based on advances in understanding its underlying pathophysiology.

Update on the Crosstalk Between Adipose Tissue and Mineral Balance in General Population and Chronic Kidney Disease

Adipose tissue is nowadays considered as a major endocrine organ, which apart from controlling lipid metabolism, displays a significant role in energy expenditure, food intake and in the regulation of various systemic physiological processes. Adipose derived pro-inflammatory cytokines and adipokines, particularly leptin and adiponectin, provide inter-communication of adipose tissue with various metabolic pathways, ultimately resulting in a complex network of interconnected organ systems. Recent clinical and experimental research has been focused on exploring the direct interaction between adipokine profile and elements of mineral metabolism, including parathormone (PTH), fibroblast growth factor-23 (FGF23) and calcitriol. The emerging crosstalk between adipose tissue and calcium and phosphorus homeostasis suggests that metabolic disorders from one system may directly affect the other and vice versa. It is current knowledge that fat metabolism disturbance, commonly encountered in obese individuals, influences the expression of calciotriopic hormones in general population, while various clinical trials attempting to successfully achieve body fat loss by modulating mineral profile have been published. In chronic kidney disease (CKD) state, there is an increasing evidence suggesting that mineral disorders, influence adipose tissue and linked endocrine function. On the contrary, the impact of disturbed fat metabolism on CKD related mineral disorders has been also evocated in clinical studies. Recognizing the pathogenetic mechanisms of communication between adipose tissue and mineral balance is critical for understanding the effects of metabolic perturbations from the one system to the other and for identifying possible therapeutic targets in case of disrupted homeostasis in one of the two connected systems. To that end, this review aims to enlighten the recent advances regarding the interplay between mineral metabolism, fat mass and adipokine profile, based on in vitro, in vivo and clinical studies, in general population and in the course of CKD.

Energy and protein requirements for children with CKD stages 2-5 and on dialysis-clinical practice recommendations from the Pediatric Renal Nutrition Taskforce

Dietary management in pediatric chronic kidney disease (CKD) is an area fraught with uncertainties and wide variations in practice. Even in tertiary pediatric nephrology centers, expert dietetic input is often lacking. The Pediatric Renal Nutrition Taskforce (PRNT), an international team of pediatric renal dietitians and pediatric nephrologists, was established to develop clinical practice recommendations (CPRs) to address these challenges and to serve as a resource for nutritional care. We present CPRs for energy and protein requirements for children with CKD stages 2-5 and those on dialysis (CKD2-5D). We address energy requirements in the context of poor growth, obesity, and different levels of physical activity, together with the additional protein needs to compensate for dialysate losses. We describe how to achieve the dietary prescription for energy and protein using breastmilk, formulas, food, and dietary supplements, which can be incorporated into everyday practice. Statements with a low grade of evidence, or based on opinion, must be considered and adapted for the individual patient by the treating physician and dietitian according to their clinical judgment. Research recommendations have been suggested. The CPRs will be regularly audited and updated by the PRNT.

Leptin and ghrelin in chronic kidney disease: their associations with protein-energy wasting

BACKGROUND

This study aimed to evaluate plasma concentrations of leptin and total ghrelin in children with chronic kidney disease (CKD) and assess their roles in protein-energy wasting (PEW).

METHODS

This study consisted of three different CKD populations [CKD group (20 patients with non-dialysis CKD), dialysis group (39 patients on dialysis), and kidney transplant (KTx) group (35 KTx recipients)] and control group (18 healthy children). Plasma leptin and total ghrelin levels were measured. Multi-frequency bioimpedance analysis was used for the assessment of fat and lean mass. PEW was defined using criteria including body mass, muscle mass, growth, serum albumin level, and protein intake.

RESULTS

While plasma leptin levels did not differ among the study groups, total ghrelin levels were significantly higher in the dialysis group (P < 0.001). Seven dialysis patients (18%) and one CKD patient (5%) but none of the KTx recipients met the criteria of PEW. Dialysis patients with PEW had lower plasma leptin levels compared to their counterparts (P = 0.018); however, total ghrelin levels did not differ between the two groups (P = 0.10). Low leptin level in dialysis patients was independently associated with lower fat mass index (P < 0.001) and lower height-specific SD scores of BMI (P = 0.019).

CONCLUSIONS

PEW is prevalent in dialysis patients. Low levels of leptin seem to be associated with PEW. Our result suggests that low leptin levels may be a consequence rather than a cause of PEW. Longitudinal studies are required to investigate this complex relationship between leptin and PEW in pediatric dialysis patients.

Outcome of kidney transplantation in pediatric patients with ANCA-associated glomerulonephritis: a single-center experience

OBJECTIVES

Data on kidney transplant outcomes for pediatric patients with end-stage renal disease (ESRD) secondary to anti-neutrophil cytoplasmic antibody glomerulonephritis (ANCA GN), particularly granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA), is limited. We describe our experience of kidney transplantation in pediatric ANCA GN patients.

METHODS

We performed a retrospective review of patients with ANCA GN who developed ESRD and were transplanted at a single center between the years 2000 and 2014.

RESULTS

Since 2000, there were seven pediatric patients with ANCA GN (four MPA) transplanted. Mean age at ANCA GN diagnosis was 11.8 ± 2.8 (range, 7.2-15.4) years. All seven were ANCA (three anti-PR3/four anti-MPO) positive. Estimated glomerular filtration rate (eGFR) at diagnosis was 11.7 ± 6.3 ml/min/1.73 m². All received steroids and cyclophosphamide and three (23.3%) received plasma exchange. Six were dialysis dependent by 6 months post diagnosis. Time from diagnosis to transplant was 30 ± 12 (range, 17-48) months. Six of the seven received a deceased donor transplant. All patients received induction therapy and standard maintenance immunosuppression post transplant. Median duration of follow-up post transplantation was 27 months (range, 13-88 months). Median eGFR at last follow-up was 77 ml/min/1.73 m² (range, 7.9-83.5). One patient lost her transplant to acute cellular rejection following non-adherence to immunosuppression after 21 months of stable transplant function. No patient had recurrence of vasculitis, either renal or extra-renal.

CONCLUSIONS

Short-term patient and allograft survival in pediatric patients with ESRD secondary to ANCA GN seems excellent, with no recurrence of vasculitis post transplant in this small cohort.

Dietary Intake, Nutritional Status, and Body Composition in Children With End-Stage Kidney Disease on Hemodialysis or Peritoneal Dialysis

OBJECTIVE(S)

This study aimed to demonstrate that dietary intake, anthropometric indicators, and body composition in children with end-stage kidney disease differs between those on peritoneal dialysis (PD) and those on hemodialysis (HD).

METHODS

This was a cross-sectional and consecutive study that included 55 children and adolescents with end-stage kidney disease who were undergoing replacement therapy (22 PD patients and 33 HD patients). Two 24-hour dietary recall surveys were conducted for each patient. Anthropometric, biochemical, and body composition indicators were estimated. A Student's t-test and a Mann-Whitney U test were used for the parametric variables, whereas association tests were estimated for the nonparametric variables (i.e., χ², Fisher exact test, and odds ratio). Regression models were designed to predict dietary intake on anthropometric and body composition indicators.

RESULTS

The mid-upper arm circumference was greater on the patients undergoing HD than on the PD patients (odds ratio = 15.8 [95% confidence interval (CI): 2.9, 85.1], P < .001); the arm muscular area was greater in the HD patients than in the PD patients (P = .07). Children on PD had significantly greater creatinine concentration (8.4 ± 3.0 mg/dL vs. 4.6 ± 1.2 mg/dL, P < .001), urea (101 ± 27 mg/dL vs. 50 ± 17 mg/dL, P < .001), and glucose (87 ± 14.4 mg/dL vs. 77 ± 10.2 mg/dL, P = .003). Children on PD had lower lipid intake (31.2 ± 15.8 vs. 40.9 ± 19.1 g/day, P = .032), lower percentage of adequacy of vitamin C (128 ± 66 vs. 146 ± 70, P = .046), and lower sodium (62 ± 43 vs. 79 ± 42, P = .044) than children on HD. Dietary intake predicted 40% to 80% of the variability in the nutritional status in children on PD and 28% to 60% in children on HD.

CONCLUSIONS

Nutritional status is affected in most patients on dialysis treatment, which differs significantly among those who are undergoing PD or HD.

Inflammation and nutrition in children with chronic kidney disease

Chronic inflammation and nutritional imbalance are important comorbid conditions that correlate with poor clinical outcomes in children with chronic kidney disease (CKD). Nutritional disorders such as cachexia/protein energy wasting, obesity and growth retardation negatively impact the quality of life and disease progression in children with CKD. Inadequate nutrition has been associated with growth disturbances in children with CKD. On the other hand, over-nutrition and obesity are associated with poor outcomes in children with CKD. The exact mechanisms leading to these unfavorable conditions are not fully elucidated and are most likely multifactorial. In this review, we focus on the pathophysiology of nutrition disorders and inflammation and their impact on clinical outcomes in children with CKD.

Correlates of leptin in children with chronic kidney disease

OBJECTIVE

To investigate the relative associations of renal function, obesity, and inflammation with serum leptin levels in children with chronic kidney disease (CKD).

STUDY DESIGN

This was a cross-sectional analysis of 317 children from the Chronic Kidney Disease in Children study, a large cohort of pediatric patients with stage II-IV CKD. Linear regression modeling was used to evaluate the association of serum leptin level with glomerular filtration rate calculated using the plasma iohexol disappearance curve, demographics, body mass index (BMI), and cardiovascular risk factors, including inflammatory cytokines, insulin resistance, and serum lipid levels.

RESULTS

In univariate analyses, elevated serum leptin level was significantly associated with increased BMI, older age, and female sex (P < .001 for all). Leptin level also correlated positively with serum triglycerides and insulin resistance (P < .001) and negatively with serum high-density lipoprotein cholesterol (P = .002). Leptin level was not associated with glomerular filtration rate calculated using the plasma iohexol disappearance curve or inflammatory cytokines. In multivariate analysis, BMI, age, female sex, and serum triglyceride levels were significantly associated with serum leptin level.

CONCLUSION

Increased leptin production was associated with female sex, older age, and adiposity in children with mild to moderate CKD. Renal function was not associated with serum leptin level, indicating that decreased clearance does not contribute to elevated leptin levels.

Assessment of nutritional status in children with chronic kidney disease and on dialysis

Protein-energy wasting (PEW) is defined as a state of decreased body protein mass and fuel reserves (body protein and fat mass) and is a common complication of chronic kidney disease (CKD). It is multifactorial: the main causative factors are hormonal imbalances and a low nutrient intake, but low residual renal function, inadequate dialysis dose, chronic inflammation and metabolic acidosis are other important contributory factors. Adult PEW has been defined, but there is no accepted definition of pediatric PEW and consequently no precise diagnostic criteria. Assessing nutritional status in children is also complicated by the absence of a gold standard, specific abnormalities in body composition, and the slowly progressive course of the disease. The evaluation of PEW should take into account all of its pathogenetic aspects, which include dietary assessment, clinical and anthropometric assessment (based on weight, height, and body mass index), a panel of biochemical parameters, and a normalized protein catabolic rate (in the case of adolescents on hemodialysis). Bioimpedance indices can be used in individual patients on a regular basis in centers with expertise. The longitudinal follow-up data relating to the above parameters are valuable for comparing patient and normative data. Given the complex nature of PEW, only a multidisciplinary approach can provide an accurate assessment of nutritional status and its derangements in children with CKD and on dialysis.

Maternal nutritional history modulates the hepatic IGF-IGFBP axis in adult male rat offspring

Alterations in early life nutrition lead to an increased risk of obesity and metabolic syndrome in offspring. We have shown that both relative maternal undernutrition (UN) and maternal obesity result in metabolic derangements in offspring, independent of the postnatal dietary environment. Since insulin-like growth factor binding protein 2 (IGFBP2) has been shown to be independently associated with obesity and diabetes risk, we examined the IGF-IGFBP axis in male rat offspring following either maternal UN or maternal obesity to explain possible common pathways in the development of metabolic disorders. Wistar rats were time-mated and fed either a control diet (CONT), 50 % of CONT (UN) or a high-fat (HF) diet throughout pregnancy. Male offspring were weaned onto a standard chow diet and blood and tissues were collected at postnatal day 160. Plasma and hepatic tissue samples were analysed for key players in the IGF-IGFBP system. Both maternal UN and HF resulted in increased fat mass, hyperinsulinemia, hyperleptinemia and altered blood lipid profiles in offspring compared to CONT. Circulating IGF-1 and IGFBP3 levels and hepatic mRNA expression of IGFBP1 and IGFBP2 were significantly decreased in UN and HF offspring compared to CONT. DNA methylation of the IGFBP2 promotor region was similar between maternal dietary groups. Although chaperone gene heat-shock protein 90 and hepatic IGFBP1 were significantly correlated in CONT offspring this effect was absent in both UN and HF offspring. In conclusion, this study is one of the first to directly compare two experimental models of developmental programming representing both ends of the maternal dietary spectrum. Our data suggest that two disparate nutritional models that elicit similar adverse metabolic phenotypes in offspring are characterised by common alterations in the IGF-IGFBP pathway.

Association between the ratio of insulin-like growth factor-I to insulin-like growth factor binding protein-3 and inflammation in incident automated peritoneal dialysis patients

BACKGROUND

The insulin-like growth factor (IGF) system is known to be associated with inflammation in various populations. However, the association between the IGF system and inflammation has not previously been investigated in automated peritoneal dialysis (APD) patients. Therefore, the aim of this study was to investigate whether the IGF system correlates with inflammation in APD patients.

METHODS

We prospectively determined IGF-I activity, the ratio of serum IGF-I concentrations to those of IGF binding protein-3 (IGFBP-3), and inflammatory markers at initiation of APD and after 6 months of follow-up in 21 incident APD patients.

RESULTS

The mean age was 55.2 ± 13.1 years, and 11 patients (52.3%) were male. Continuous cyclic PD (CCPD) was performed in 11 patients, and nocturnal intermittent PD (NIPD) in 10 patients. The mean value of IGF-I/IGFBP-3 was 0.21 ± 0.13. At baseline, IGF-I/IGFBP-3 was negatively correlated with high-sensitivity C-reactive protein (hs-CRP) (r = -0.27, P = 0.032) and interleukin-6 (IL-6) (r = -0.19, P = 0.046) concentrations. After 6 months, IGF-I/IGFBP-3 (P = 0.048) had decreased significantly, while the hs-CRP (P = 0.036) increased significantly in the CCPD group. However, there were no significant changes in IGF-I/IGFBP-3 (P = 0.59) and hs-CRP (P = 0.14) during 6 months in the NIPD group. Furthermore, compared with the NIPD group, IGF-I/IGFBP-3 (P = 0.041) decreased greater, whereas hs-CRP (P = 0.048) concentrations increased greater in the CCPD group.

CONCLUSIONS

The IGF system was significantly associated with inflammatory markers in incident APD patients, and different APD modalities modulate the IGF system and inflammation.

Ghrelin and leptin pathophysiology in chronic kidney disease

Ghrelin is an orexigenic hormone with additional effects on the regulation of inflammation and the cardiovascular system. It may play an important role in the pathogenesis of cachexia/protein-energy wasting (PEW), inflammation and cardiovascular complications in chronic kidney disease (CKD). There are three circulating gene products of ghrelin, namely, acyl ghrelin, des-acyl ghrelin and obestatin, each with individual distinct functions. Perturbations of these circulating ghrelin proteins impact the overall milieu of CKD. Leptin is an anorexigenic hormone which is secreted from the adipocytes and interacts with ghrelin and other appetite-regulating hormones. Leptin also plays a role in regulating inflammation and the cardiovascular system. Indeed, ghrelin and leptin may play yin-and-yang roles in CKD pathophysiology. Clinical trials involving the use of the mimetics or antagonists of these hormones are limited to short-term phase I/II studies. Further understanding of their interactions in CKD pathophysiology is needed for potential large-scale clinical trials, which may impact the quality of life and survival of patients with CKD.

Leptin is better than any other biological parameter for monitoring the efficacy of renutrition in hospitalized malnourished elderly patients

OBJECTIVE

Despite malnutrition being a major problem in hospitalized elderly patients, there is a lack of studies focusing on the comparative value of biological parameters for monitoring renutrition. The aim of this study was to determine which biological parameter(s) could best monitor successful renutrition in hospitalized malnourished elderly patients.

DESIGN

The objective of the study was to explore the impact of a 6-week renutrition process on anthropometric and biological parameters in elderly patients and to define the biological parameters associated with weight regain.

PATIENTS

A total of 72 hospitalized malnourished elderly patients admitted to a hospital-based geriatric rehabilitation unit.

MEASUREMENTS

Patients were evaluated at admission and at 6 weeks for anthropometric measurements of weight, sum of the four subcutaneous skinfold thicknesses, calf circumference and biological serum parameters including albumin, transthyretin, leptin, IGF-1, IGFBP-1 and IGFBP-3. Renutrition was considered successful if a patient gained at least 5% of body weight over 6 weeks.

RESULTS

Leptin was the only biological parameter that increased at 6 weeks in successful renutrition. Leptin variations were not influenced by C-reactive protein variations, in contrast to transthyretin which can be modified by the inflammatory states frequently encountered in geriatric patients.

CONCLUSIONS

Serum leptin is a more appropriate parameter than transthyretin for monitoring renutrition.

Plasma levels of acylated and total ghrelin in pediatric patients with chronic kidney disease

This cross-sectional study set out to compare total and acyl ghrelin levels in children with mild chronic kidney disease (CKD) undergoing conservative treatment (n = 19) with children with end-stage renal disease (ESRD) undergoing hemodialysis (n = 24), and with healthy controls (n = 20). The relationship between ghrelin levels and parameters of renal function, nutritional status, and selective hormones were investigated. ESRD patients had higher total ghrelin levels than those with mild CKD or control individuals. However, acyl ghrelin did not differ between groups, indicating that the excess circulating ghrelin was desacylated. Since desacyl ghrelin has been shown to inhibit appetite, increased levels might contribute to protein-energy wasting in pediatric renal patients. When all 43 renal patients were combined, multiple regression analysis found age and glomerular filtration rate (GFR) to be significant negative predictors of total ghrelin. Acyl ghrelin was influenced negatively by age and positively by energy intake. Acyl to total ghrelin ratio related positively to GFR and energy intake. The results indicate that total but not acyl ghrelin is influenced by low GFR in children with CKD and suggests that ghrelin activation may be impaired in these patients. Since energy intake is a positive predictor of acyl ghrelin, the physiological control of ghrelin secretion appears to be altered in pediatric renal patients.

Improvement in growth after 1 year of growth hormone therapy in well-nourished infants with growth retardation secondary to chronic renal failure: results of a multicenter, controlled, randomized, open clinical trial

BACKGROUND AND OBJECTIVES

Our aim was to evaluate the growth-promoting effect of growth hormone (GH) treatment in infants with chronic renal failure (CRF) and persistent growth retardation despite adequate nutritional and metabolic management.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The study design included randomized, parallel groups in an open, multicenter trial comparing GH (0.33 mg/kg per wk) with nontreatment with GH during 12 months. Sixteen infants who had growth retardation, were aged 12+/-3 months, had CRF (GFR<or=60 ml/min per 1.73 m2), and had adequate nutritional intake and good metabolic control were recruited from eight pediatric nephrology departments from Spain and Portugal. Main outcome measures were body length, body weight, bone age, biochemical and hormonal analyses, renal function, bone mass, and adverse effects.

RESULTS

Length gain in infants who were treated with GH was statistically greater (P<0.05) than that of nontreated children (14.5 versus 9.5 cm/yr; SD score 1.43 versus -0.11). The GH-induced stimulation of growth was associated with no undesirable effects on bone maturation, renal failure progression, or metabolic control. In addition, GH treatment improved forearm bone mass and increased serum concentrations of total and free IGF-I and IGF-binding protein 3 (IGFBP-3), whereas IGF-II, IGFBP-1, IGFBP-2, GH-binding protein, ghrelin, and leptin were not modified.

CONCLUSIONS

Infants with CRF and growth retardation despite good metabolic and nutritional control benefit from GH treatment without adverse effects during 12 months of therapy.

Nutrition assessment and management in children on peritoneal dialysis

Protein-calorie malnutrition, otherwise known as cachexia, is a common problem in children undergoing chronic peritoneal dialysis (PD) and is a frequent source of significant morbidity and mortality. Recent evidence suggests that the main factors involved in the pathogenesis are metabolic acidosis, a decreased response to anabolic hormones, and chronic inflammation, associated with hormonal imbalances and an increased metabolic rate. Given the complexity and multifactorial nature of cachexia, the assessment of nutritional status in children on PD requires a complete history and physical examination; assessment of dietary intake, biochemical indices, and anthropometry; and possibly bioimpedance analysis and combined score systems. Its management should likewise be multidisciplinary and include ensuring an adequate energy and protein intake; optimal metabolic control, with the correction of acidosis, anaemia, and hyperparathyroidism; an optimal (or at least adequate) dialysis dose; and, if necessary, prescription of specific drugs such as recombinant human growth hormone.

Children with chronic kidney disease: a 3-year prospective study of growth, bone mass and bone turnover

AIM

Children with chronic kidney disease (CKD) are at risk of developing skeletal problems. This 3-year prospective study investigated the development of bone mass and bone turnover in children with CKD.

METHODS

Fifteen patients, 4-15 years, were included with a median glomerular filtration rate of 48 (range 8-94) mL/min/1.73 m(2). Bone mineral density (BMD) and markers of bone and mineral metabolism were investigated over a 3-year period.

RESULTS

Growth was satisfactory but a delayed bone age was observed. Total body bone mineral density (TBBMD) Z-scores were below zero in five patients at start and after 3 years, but none had a Z-score below -2.5. Lumbar spine BMD Z-scores were below zero in three patients at start and in five patients after 3 years. The median TBBMD and lumbar spine Z-scores did not change during the study period. Eleven CKD patients had increased PTH levels at baseline and 13 patients after 3 years. Most children had normal levels of leptin and vitamin D. Almost 50% of the patients had increased osteoprotegerin levels after 3 years.

CONCLUSION

A normal BMD does not exclude mineral bone disorder in patients with CKD, yet the BMD Z-scores were well preserved and most markers of bone turnover were within the reference intervals.

Nutrition in children with CRF and on dialysis

The objectives of this study are: (1) to understand the importance of nutrition in normal growth; (2) to review the methods of assessing nutritional status; (3) to review the dietary requirements of normal children throughout childhood, including protein, energy, vitamins and minerals; (4) to review recommendations for the nutritional requirements of children with chronic renal failure (CRF) and on dialysis; (5) to review reports of spontaneous nutritional intake in children with CRF and on dialysis; (6) to review the epidemiology of nutritional disturbances in renal disease, including height, weight and body composition; (7) to review the pathological mechanisms underlying poor appetite, abnormal metabolic rate and endocrine disturbances in renal disease; (8) to review the evidence for the benefit of dietetic input, dietary supplementation, nasogastric and gastrostomy feeds and intradialytic nutrition; (9) to review the effect of dialysis adequacy on nutrition; (10) to review the effect of nutrition on outcome.

Bone mass, biochemical markers and growth in children with chronic kidney disease: a 1-year prospective study

AIM

This study was designed to investigate bone mineral density (BMD), growth parameters and biochemical markers in children with chronic kidney disease (CKD).

METHODS

Sixteen patients, 4-18 years, with CKD were prospectively followed for 1 year. Auxological data, body composition, BMD by dual-energy X-ray absorptiometry, bone age, bone turnover markers, vitamin D, parathyroid hormone (PTH), leptin, osteoprotegerin, insulin-like growth factor-I (IGF-I) and IGF binding protein-3 were measured. A questionnaire regarding bone health and diet was also performed.

RESULTS

Delayed bone age was observed (n = 11) and the BMD Z-scores for total body were below zero in seven patients. However, total body BMD (TBBMD) increased in 12 patients. Most patients had increased osteocalcin and carboxy-terminal telopeptide of type I collagen, but normal alkaline phosphatase, type I procollagen intact amino-terminal propeptide and tartrate-resistant acid phosphatase 5b. Ten patients had increased PTH. Most children had normal levels of leptin, osteoprotegerin, IGF-I and IGFBP-3. Leptin, at baseline, correlated with differences in TBBMD over 1 year.

CONCLUSIONS

Only seven (44%) had negative Z-scores and TBBMD increased over 1 year. Bone markers at baseline did not predict the longitudinal changes in BMD.

Leptin and resistin levels and their relationships with glucose metabolism in children with chronic renal insufficiency and undergoing dialysis

AIM

The aim of the present study is: (i) to evaluate the serum concentrations of leptin and resistin in the paediatric patients with chronic renal impairment (CRI), on haemodialysis (HD) and on peritoneal dialysis (PD) treatment; (ii) to examine the relationship between these hormones; and (iii) to investigate the possible influence of these hormones on the insulin resistance and sensitivity indexes as well as on serum insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding protein-3 (IGFBP-3) levels.

METHODS

In total, 52 patients (15 patients with CRI, 24 PD patients and 13 HD patients) and 23 healthy age- and sex-matched control subjects were included in the present study.

RESULTS

Homeostasis model assessment of insulin resistance (HOMA-IR) was higher than 2.5 in 47.1% of the patients. IGF-1 levels of patients with CRI, PD and HD patients were significantly lower than those in the controls (P < 0.001, P < 0.001, P < 0.001, respectively). The leptin levels of patients with CRI and on PD and HD treatment were significantly higher than the control group (P = 0.038, P = 0.002, P = 0.006, respectively). Similarly, serum resistin levels of patients with CRI and those of PD and HD patients were higher when compared with healthy controls (P = 0.037, P < 0.001, P = 0.005, respectively).

CONCLUSION

Leptin and resistin levels were increased in the children with CRF; however, this elevation was not found to be associated with hyperinsulinism. Further studies to explain the mechanisms and consequences of the accumulation of these hormones in CRF may provide the therapeutical approach aiming to normalize their circulating levels.

Nondiabetic consequences of obesity on kidney

There has been a major increase in obesity among children over the past twenty years. Obesity is associated with glomerular hyperperfusion and hyperfiltration from physiological (mal)adaptation resulting from afferent arteriolar vasodilatation. The renal injury from hyperfiltration in obesity is further exacerbated by concomitant presence of dyslipidemia, hyperglycemia and/or insulin resistance, inflammation and hypertension. The renal injury clinically manifests as microalbuminuria, proteinuria and/or poor renal function, and is histologically characterized by glomerulomegaly, mesangial expansion and/or sclerosis, which has been termed "obesity related glomerulopathy". Obesity portends a poor prognosis in subjects with chronic kidney diseases, IgA nephropathy and nephrectomy. Obese individuals on dialysis and renal transplant have mixed outcomes. The purpose of this review is to highlight the nondiabetic consequences of obesity on kidney for the pediatric nephrology community as we begin to address the obesity epidemic in children.

The future of pediatric nephrology

The delineation of renal disease in children dates to the 1880s with descriptions of Henoch's purpura, bladder exstrophy, renal rickets and nephritis. The discipline of pediatric nephrology mainly emerged during the 20th century in response to problems in fluid and electrolyte balance, characterization of the nephrotic syndrome, use of renal biopsy, antibiotic therapy of urinary tract infections, dialysis and transplantation in children, growth problems associated with chronic renal failure, detection and therapy of hypertension, and the creation of both national and international pediatric nephrology societies and a journal now in its 18th year. The development of molecular and cell biology, genetic and genomic techniques and bioinformatics methods underlie many future directions. We should anticipate further elucidation of single gene disorders, of complex trait analysis of disorders, such as diabetic nephropathy and hypertension, the interplay of developmental genes and gene products and interactions within the podocyte. Specific therapies directed against inflammation, vascular damage, cyst development, the ravages of proteinuria and graft rejection (or induction leading to tolerance) will be developed. Stem cell therapies may replace lost renal mass, even of specific nephron sites. Novel therapies will also modulate the cell cycle, tyrosine kinase signaling and apoptosis. In addition, drugs will be specifically tested in children for many renal conditions. Larger and more specialized registries will be developed; epidemiologic studies and exploration of large data sets will lead to clinical guidelines that are evidenced-based. There is a need for more careful measurement of glomerular filtration rate (GFR), proteinuria and cytokines, and a fuller appreciation of the nutritional and hormonal role of the kidney. Finally, the antecedents of adult renal disease and the need to intervene in a proactive fashion will be realized. Despite these impressive advances in care, the greatest challenges will be in providing children with renal disease access to well-trained pediatric nephrologists, especially in Asia (1 billion children), Africa, Central and South America, and in immigrant and refugee populations. Included in this challenge is the capacity to have affordable access to use of contemporary techniques, and effective medications and prevention strategies. The International Pediatric Nephrology Association (IPNA), its journal, and pediatric advocates will need to use their energies to take on these challenges.

Correction of Hemodialysis Anemia is Associated with Significant Increase in Serum Concentration of IGF-I in Patients Treated with Erythropoietin: A Randomized Controlled Study

BACKGROUND

The effect of erythropoietin (EPO) therapy on the serum level of IGF-I among hemodialysis patients is debated. The aim of this study is to study the effect of EPO on the erythropoiesis and the change of serum level of IGF-I among adequately hemodialyzed patients.

PATIENTS AND METHODS

Forty patients (25 males and 15 females) who had an adequate level of both hemodialysis and nutrition were randomly allocated into two equal groups. Besides parenteral iron, the first group of patients received a conventional EPO dose regimen of 2000 U subcutaneously (SC) thrice weekly, the second group of patients remained on parenteral iron and ranked as a control group. The patients were subjected to thorough laboratory investigations. IGF-I concentration was measured before and at the end of the study.

RESULTS

Both groups were comparable in their demographic, laboratory, dialysis level, and nutritional status. There was no statistical differences in hemoglobin, hematocrit %, iron store indices and serum level of IGF-I at the study entry. We found a significant rise of both hemoglobin and hematocrit as well as IGF-I serum level in the EPO group at the end of the study in comparison to their values at the starting points in comparison to the control group (P< 0.001).

CONCLUSION

Erythropoietin therapy enhances erythropoiesis and modulates the serum concentration of IGF-I.