Bone mineral density, bone metabolism and body composition of children with chronic renal failure, with and without growth hormone treatment

Growth hormone in pediatric chronic kidney disease: more than just height

Recombinant human growth hormone therapy, which was introduced in the 1980s, is now routine for children with advanced chronic kidney disease (CKD) who are exhibiting growth impairment. Growth hormone usage remains variable across different centers, with some showing low uptake. Much of the focus on growth hormone supplementation has been on increasing height because of social and psychological effects of short stature. There are, however, numerous other changes that occur in CKD that have not received as much attention but are biologically important for pediatric growth and development. This article reviews the current knowledge about the multisystem effects of growth hormone therapy in pediatric patients with CKD and highlights areas where additional clinical research is needed. We also included clinical data on children and adults who had received growth hormone for other indications apart from CKD. Ultimately, having robust clinical studies which examine these effects will allow children and their families to make more informed decisions about this therapy.

Malnutrition Patterns in Children with Chronic Kidney Disease

Malnutrition is frequent in children with chronic kidney disease (CKD). Apart from undernutrition and protein energy wasting (PEW), overnutrition prevalence is rising, resulting in fat mass accumulation. Sedentary behavior and unbalanced diet are the most important causal factors. Both underweight and obesity are linked to adverse outcomes regarding renal function, cardiometabolic risk and mortality rate. Muscle wasting is the cornerstone finding of PEW, preceding fat loss and may lead to fatigue, musculoskeletal decline and frailty. In addition, clinical data emphasize the growing occurrence of muscle mass and strength deficits in patients with fat mass accumulation, attributed to CKD-related wasting processes, reduced physical activity and possibly to obesity-induced inflammatory diseases, leading to sarcopenic obesity. Moreover, children with CKD are susceptible to abdominal obesity, resulting from high body fat distribution into the visceral abdomen compartment. Both sarcopenic and abdominal obesity are associated with increased cardiometabolic risk. This review analyzes the pathogenetic mechanisms, current trends and outcomes of malnutrition patterns in pediatric CKD. Moreover, it underlines the importance of body composition assessment for the nutritional evaluation and summarizes the advantages and limitations of the currently available techniques. Furthermore, it highlights the benefits of growth hormone therapy and physical activity on malnutrition management.

Muscle-bone axis in children with chronic kidney disease: current knowledge and future perspectives

Bone and muscle tissue are developed hand-in-hand during childhood and adolescence and interact through mechanical loads and biochemical pathways forming the musculoskeletal system. Chronic kidney disease (CKD) is widely considered as both a bone and muscle-weakening disease, eventually leading to frailty phenotype, with detrimental effects on overall morbidity. CKD also interferes in the biomechanical communication between two tissues. Pathogenetic mechanisms including systemic inflammation, anorexia, physical inactivity, vitamin D deficiency and secondary hyperparathyroidism, metabolic acidosis, impaired growth hormone/insulin growth factor 1 axis, insulin resistance, and activation of renin-angiotensin system are incriminated for longitudinal uncoordinated loss of bone mineral content, bone strength, muscle mass, and muscle strength, leading to mechanical impairment of the functional muscle-bone unit. At the same time, CKD may also interfere in the biochemical crosstalk between the two organs, through inhibiting or stimulating the expression of certain osteokines and myokines. This review focuses on presenting current knowledge, according to in vitro, in vivo, and clinical studies, concerning the pathogenetic pathways involved in the muscle-bone axis, and suggests approaches aimed at preventing bone loss and muscle wasting in the pediatric population. Novel therapeutic targets for preserving musculoskeletal health in the context of CKD are also discussed.

Skeletal manifestations of renal disease in childhood

PURPOSE OF REVIEW

This review summarizes recent findings on musculoskeletal health in three chronic renal conditions of childhood: chronic kidney disease stages 2-5D, nephrotic syndrome, and urolithiasis. Findings with important clinical implications warranting further investigation are highlighted.

RECENT FINDINGS

Recent cohort studies have demonstrated a high burden of fracture and progressive deficits of cortical bone in children with chronic kidney disease. Lower cortical density is associated with incident fracture and may be an important therapeutic target. Parathyroid hormone and calcium are independent correlates of cortical density, and modifiable factors for fracture include parathyroid hormone and phosphate binder use. Children with nephrotic syndrome, even with normal renal function, have evidence of abnormal bone metabolism and structure, and vitamin D deficiency may be an important modifiable risk factor in this population. Urolithiasis has been associated with reduced bone mineral density and is increasingly common in children and adolescents. Population-based data found a significantly increased risk of fracture in adolescent males and young women.

SUMMARY

Recent findings substantiate concern regarding the particular vulnerability of the growing skeleton to chronic renal disease. Studies are needed to determine how to optimize assessment and management of bone health in children with these conditions, particularly in terms of calcium and vitamin D requirements, with the goal of improving childhood bone accrual for lifelong fracture prevention.

Growth and Nutrition in Pediatric Chronic Kidney Disease

Children with chronic kidney disease (CKD) feature significant challenges to the maintenance of adequate nutrition and linear growth. Moreover, the impaired nutritional state contributes directly to poor growth. Therefore, it is necessary to consider nutritional status in the assessment of etiology and treatment of sub-optimal linear growth. The major causes of poor linear growth including dysregulation of the growth hormone/insulin-like growth factor-I (IGF-I) axis, nutritional deficiency, metabolic acidosis, anemia, renal osteodystrophy/bone mineral disease, and inflammation. This review summarizes the causes and assessment tools of growth and nutrition while providing a summary of state of the art therapies for these co-morbidities of pediatric CKD.

The skeletal consequences of growth hormone therapy in dialyzed children: a randomized trial

BACKGROUND AND OBJECTIVE

The effects of recombinant human growth hormone on renal osteodystrophy are unknown; thus, the effects of growth hormone (GH) on bone histomorphometry were assessed in pediatric patients with ESRD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Thirty-three patients who underwent bone biopsy between July 1994 and May 1999 were randomly assigned to therapy with or without GH. Patients were stratified by bone formation rate; all patients with high bone turnover received intraperitoneal calcitriol. Serum biochemical values were obtained monthly, and bone biopsy was repeated after 8 months.

RESULTS

Median patient age was 11.7 years (interquartile range [IQR], 7.6, 14.1 years); 45% of patients were male, and 52% were prepubertal. Median dialysis duration was 0.4 (IQR, 0.3, 0.8) year. Bone formation rate per bone surface increased from 15.0 (9.6, 21.8) to 154.6 (23.7, 174.3) μm(2)/μm(3) per year (P=0.05) in patients with low bone turnover treated with GH, decreased from 103.3 (57.0, 173.4) to 60.3 (20.3, 13.7) μm(2)/μm(3) per year in patients with high bone turnover receiving standard therapy (P=0.03), and was unchanged in the other two groups. Bone formation rates were higher with GH, irrespective of underlying bone histologic features (P=0.05). Parathyroid hormone did not differ between groups. GH therapy resulted in greater increases in height SD scores (estimated mean difference in change ± SD, 0.324±0.076; P<0.001), irrespective of underlying bone histologic features.

CONCLUSIONS

GH therapy improves height in pediatric dialysis patients, irrespective of underlying bone histologic features. Bone formation rates are higher in GH recipients, and GH therapy alters the relationship between circulating parathyroid hormone values and bone turnover.

Changes in bone structure and the muscle-bone unit in children with chronic kidney disease

The impact of pediatric chronic kidney disease (CKD) on acquisition of volumetric bone mineral density (BMD) and cortical dimensions is lacking. To address this issue, we obtained tibia quantitative computed tomography scans from 103 patients aged 5-21 years with CKD (26 on dialysis) at baseline and 12 months later. Gender, ethnicity, tibia length, and/or age-specific Z-scores were generated for trabecular and cortical BMD, cortical area, periosteal and endosteal circumference, and muscle area based on over 700 reference subjects. Muscle area, cortical area, and periosteal and endosteal Z-scores were significantly lower at baseline compared with the reference cohort. Cortical BMD, cortical area, and periosteal Z-scores all exhibited a significant further decrease over 12 months. Higher parathyroid hormone levels were associated with significantly greater increases in trabecular BMD and decreases in cortical BMD in the younger patients (significant interaction terms for trabecular BMD and cortical BMD). The estimated glomerular filtration rate was not associated with changes in BMD Z-scores independent of parathyroid hormone. Changes in muscle and cortical area were significantly and positively associated in control subjects but not in CKD patients. Thus, children and adolescents with CKD have progressive cortical bone deficits related to secondary hyperparathyroidism and potential impairment of the functional muscle-bone unit. Interventions are needed to enhance bone accrual in childhood-onset CKD.

Volumetric bone mineral density and bone structure in childhood chronic kidney disease

Chronic kidney disease (CKD) is associated with increased fracture risk and skeletal deformities. The impact of CKD on volumetric bone mineral density (vBMD) and cortical dimensions during growth is unknown. Tibia quantitative computed tomographic scans were obtained in 156 children with CKD [69 stages 2 to 3, 51 stages 4 to 5, and 36 stage 5D (dialysis)] and 831 healthy participants aged 5 to 21 years. Sex-, race-, and age- or tibia length-specific Z-scores were generated for trabecular BMD (TrabBMD), cortical BMD (CortBMD), cortical area (CortArea) and endosteal circumference (EndoC). Greater CKD severity was associated with a higher TrabBMD Z-score in younger participants (p < .001) compared with healthy children; this association was attenuated in older participants (interaction p < .001). Mean CortArea Z-score was lower (p < .01) in CKD 4-5 [-0.49, 95% confidence interval (CI) -0.80, -0.18)] and CKD 5D (-0.49, 95% CI -0.83, -0.15) compared with healthy children. Among CKD participants, parathyroid hormone (PTH) levels were positively associated with TrabBMD Z-score (p < .01), and this association was significantly attenuated in older participants (interaction p < .05). Higher levels of PTH and biomarkers of bone formation (bone-specific alkaline phosphatase) and resorption (serum C-terminal telopeptide of type 1 collagen) were associated with lower CortBMD and CortArea Z-scores and greater EndoC Z-score (r = 0.18-0.36, all p ≤ .02). CortBMD Z-score was significantly lower in CKD participants with PTH levels above versus below the upper limit of the Kidney Disease Outcome Quality Initiative (KDOQI) CKD stage-specific target range: -0.46 ± 1.29 versus 0.12 ± 1.14 (p < .01). In summary, childhood CKD and secondary hyperparathyroidism were associated with significant reductions in cortical area and CortBMD and greater TrabBMD in younger children. Future studies are needed to establish the fracture implications of these alterations and to determine if cortical and trabecular abnormalities are reversible.

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.

Avaliação nutricional de crianças com doença renal crônica

OBJETIVO:Desnutrição constitui uma frequente complicação em crianças portadoras de doença renal, sendo a baixa estatura o principal sinal clínico. O objetivo deste estudo é analisar o estado nutricional de crianças portadoras de doença renal por meio da antropometria. MÉTODOS:Estudo transversal que avaliou 21 (43%) meninos e 28 (57%) meninas, com idades entre 5,3 e 19,5 anos. As crianças foram divididas em três grupos, de acordo com o clearance (mL/min/1,73m2): Grupo 1, clearance >37 (n=19); Grupo 2, entre 15 e 37 (n=9) e Grupo 3 com clearance <15 (n=21). A partir do peso e da estatura, calcularam-se os seguintes indicadores: Peso/Idade (P/I), Estatura/Idade (E/I) e índice de massa corpórea (IMC) e obtiveram-se os escores Z respectivos. Escores Z menores que -2 foram considerados desnutrição. Os grupos foram comparados por ANOVA. RESULTADOS:Não se evidenciaram diferenças entre os grupos no que diz respeito aos dados antropométricos. 19 pacientes (38,8%) apresentaram baixa estatura e 22 (44,8%), baixo peso. Também não se observaram diferenças entre os grupos quando comparados pelos valores dos indicadores P/I, E/I e IMC. Os valores dos escores Z para os indicadores P/I, E/I e IMC foram: P/I - Grupo 1: -1,9±1,8; Grupo 2: -2,6±3,1; Grupo 3: -2,5±1,4 (p=0,47); E/I - Grupo 1: -1,5±1,2; Grupo 2: -2,3±1,8; Grupo 3: -2,1±1,1 (p=0,18) e IMC - Grupo 1: -1,2±1,4; Grupo 2: -1,7±3,9; Grupo 3: -1,6±1,3 (p=0,82). CONCLUSÕES: A amostra estudada apresentou alta prevalência de desnutrição. Mesmo considerando-se o estágio da doença, não se encontraram diferenças significativas entre os grupos.

Randomized controlled trial to investigate the effects of growth hormone treatment on scoliosis in children with Prader-Willi syndrome

CONTEXT

The prevalence of scoliosis in children with Prader-Willi syndrome (PWS) is 30-80%, depending on age. Although reports about effects of GH treatment on scoliosis in children with PWS are limited, scoliosis is generally considered a contraindication for GH treatment.

OBJECTIVE

The aim was to study the effects of GH treatment on the onset of scoliosis and curve progression in children with PWS.

DESIGN

We conducted a multicenter, randomized, controlled GH study in infants and prepubertal and pubertal children. Infants and prepubertal children were randomized into a GH-treated group (1.0 mg/m(2) . d) and a control group for 1 and 2 yr, respectively. Pubertal children were randomized to receive somatropin 1.0 or 1.5 mg/m(2) . d. Yearly, x-rays of the spine were taken, and height, weight, truncal lean body mass (with dual energy x-ray absorptiometry), and IGF-I were measured.

PATIENTS

A total of 91 children with PWS (median age, 4.7 yr; interquartile range, 2.1-7.4) participated in the study.

MAIN OUTCOME MEASURES

We measured the onset of scoliosis (Cobb >10 degrees ) and scoliotic curve progression.

RESULTS

GH-treated children had similar onset of scoliosis and curve progression as randomized controls (P = 0.27-0.79 and P = 0.18-0.98, respectively). GH treatment, IGF-I sd score (SDS), and catch-up growth had no adverse effect on the onset of scoliosis or curve progression, even after adjustment for confounders. Height SDS, truncal lean body mass, and IGF-I SDS were significantly higher in GH-treated children than in randomized controls. At baseline, a higher IGF-I SDS was associated with a lower severity of scoliosis.

CONCLUSIONS

Scoliosis should no longer be considered a contraindication for GH treatment in children with PWS.

Pediatric dual-energy X-ray absorptiometry: technique, interpretation, and clinical applications

This article reviews the dual-energy x-ray absorptiometry (DXA) technique, its interpretation, and clinical applications with emphasis on the considerations unique to pediatrics. Specifically, the use of DXA in children requires the radiologist to be a "clinical pathologist," monitoring the technical aspects of the DXA acquisition, a "statistician" knowledgeable in the concepts of Z-scores and least significant changes, and a "bone specialist," aware of the DXA findings in a large number of clinical diseases, providing the referring clinician with a meaningful context for the numeric result obtained with DXA.

Pediatric DXA: clinical applications

Normal bone mineral accrual requires adequate dietary intake of calcium, vitamin D and other nutrients; hepatic and renal activation of vitamin D; normal hormone levels (thyroid, parathyroid, reproductive and growth hormones); and neuromuscular functioning with sufficient stress upon the skeleton to induce bone deposition. The presence of genetic or acquired diseases and the therapies that are used to treat them can also impact bone health. Since the introduction of clinical DXA in pediatrics in the early 1990s, there has been considerable investigation into the causes of low bone mineral density (BMD) in children. Pediatricians have also become aware of the role adequate bone mass accrual in childhood has in preventing osteoporotic fractures in late adulthood. Additionally, the availability of medications to improve BMD has increased with the development of bisphosphonates. These factors have led to the increased utilization of DXA in pediatrics. This review summarizes much of the previous research regarding BMD in children and is meant to assist radiologists and clinicians with DXA utilization and interpretation.

Growth and body composition in children with chronic kidney disease

Growth failure is a common yet complex problem of childhood chronic kidney disease caused by multiple factors encountered due to the primary disease or secondary to the renal impairment. This review seeks to describe the various patho-physiological mechanisms contributing to growth failure in the various stages of childhood with particular emphasis on nutritional problems and endocrine dysfunction encountered whilst managing these children. In addition, we shall examine the role of body composition in chronic kidney disease, their relationship with growth and nutrition and the potential effect of abnormalities in fat mass and lean mass on long-term morbidity and mortality.

Bone mineral density in children with chronic renal failure

Bone mineral density (BMD) is important in children and adolescents because of its relationship to long-term skeletal health, and because, in adults with chronic renal failure (CRF), a relationship between low BMD and vascular calcification has been suggested. To investigate the relationship between BMD and manipulable factors that might affect it, i.e. plasma calcium, phosphate and parathyroid hormone (PTH), 64 patients with a median glomerular filtration rate (GFR) of 31 (range 7-60) ml min(-1) 1.73 m(-2) and median age of 10.0 (4.1-16.9) years were followed over 1.3 (0.7-1.7) years at an average of 5 (3-14) clinic visits. At one visit, BMD of the lumbar spine was measured by dual energy X-ray absorptiometry. The mean BMD Z-score was normal (=0.0). Overall mean calcium, phosphate and PTH levels were in their respective normal ranges. The majority of the patients (72%) were treated with calcium carbonate, mean dose 65 mg kg(-1) day(-1); prescription was positively related to serum calcium levels and calcium-phosphate product (P=0.012 and P<0.01 respectively). Almost all patients (98%) were treated with alfacalcidol, mean dose 12 ng kg(-1) day(-1); prescription was not related to investigated factors. Patients grew well; there was no change in height standard deviation score (DeltaHtSDS=0.0). Normal BMD Z-score for age and sex can be achieved in children with CRF managed with the aim of maintaining normal PTH levels by dietary phosphate restriction, calcium-based phosphate binders and small doses of alfacalcidol. Further investigation of the underlying bone by the use of biopsy and histomorphometry is required to determine actual bone health.

Low bone mass in children and adolescents

Osteoporosis is a disease characterized by low bone mass and micro architectural alterations of bone tissue leading to enhanced bone fragility and increased fracture risk. Although research in osteoporosis has focused mainly on the role of bone loss in the elderly population, it is becoming increasingly clear that the amount of bone that is gained during growth is also an important determinant of future resistance to fractures. Thus, considerable interest is being placed on defining preventive strategies that optimize the gain of bone mass during childhood and adolescence. Knowledge of the determinants accounting for the physiologic and genetic variations in bone accumulation in children will provide the best means toward the early diagnosis and treatment of osteoporosis. This article reviews the techniques available for bone mass measurements in children and the major determinants and diseases influencing bone accretion during childhood and adolescence.

Metabolic Bone Disease in Children

Metabolic bone disease in children includes many hereditary and acquired conditions of diverse etiology that lead to disturbed metabolism of the bone tissue. Some of these processes primarily affect bone; others are secondary to nutritional deficiencies, a variety of chronic disorders, and/or treatment with some drugs. Some of these disorders are rare, but some present public health concerns (for instance, rickets) that have been well known for many years but still persist. The most important clinical consequences of bone metabolic diseases in the pediatric population include reduced linear growth, bone deformations, and non-traumatic fractures leading to bone pain, deterioration of motor development and disability. In this article, we analyze primary and secondary osteoporosis, rickets, osteomalacia (nutritional and hereditary vitamin D-dependent, hypophosphatemic and that due to renal tubular abnormalities), renal osteodystrophy, sclerosing bony disorders, and some genetic bone diseases (hypophosphatasia, fibrous dysplasia, skeletal dysplasia, juvenile Paget disease, familial expansile osteolysis, and osteoporosis pseudoglioma syndrome). Early identification and treatment of potential risk factors is essential for skeletal health in adulthood. In most conditions it is necessary to ensure an appropriate diet, with calcium and vitamin D, and an adequate amount of physical activity as a means of prevention. In secondary bone diseases, treatment of the primary disorder is crucial. Most genetic disorders await prospective gene therapies, while bone marrow transplantation has been attempted in other disorders. At present, affected patients are treated symptomatically, frequently by interdisciplinary teams. The role of exercise and pharmacologic therapy with calcium, vitamin D, phosphate, bisphosphonates, calcitonin, sex hormones, growth hormone, and thiazides is discussed. The perspectives on future therapy with insulin-like growth factor-1, new analogs of vitamin D, strontium, osteoprotegerin, and calcimimetics are presented.

Osteoporosis and measurement of bone mass in children and adolescents

Osteoporosis increasingly is recognized as a pediatric concern. Fragility fractures occur in children and adolescents with genetic disorders and those with a variety of chronic diseases. Others may not fracture in childhood but reach adulthood with a reduced peak bone mass and increased lifelong risk of osteoporosis. This article reviews the indications for pediatric bone density testing, the strengths and limitations of densitometry methods, and the challenges of interpreting the results. The goals are to demystify the densitometry report and to clarify the role of bone density tests in assessing and managing skeletal health in children.

Long-term outcome of growth hormone therapy in children and adolescents

Growth hormone (GH) has been available for more than 4 decades for the treatment of GH deficiency. Initially, GH was extracted from the pituitary glands of human cadavers, but its use was discontinued following the transmission of the Creutzfeldt-Jakob virus. After the development of recombinant GH (somatropin) in 1985, an 'unlimited' commercial source of GH has been available, allowing for the treatment of a large number of short GH-deficient and -sufficient children. Refinements in both the dosage and the frequency of administration of GH have allowed GH-deficient children to reach nearly normal final heights, although mostly they are still below their target heights. Decreased bone mineral densities and increased concentrations of fasting and postprandial lipids, coagulation factors, and several independent cardiovascular risk factors have been reported in GH-deficient children and adolescents and appear to improve with GH administration. The short-term administration of GH to mostly non-GH-deficient short children with Turner syndrome, chronic renal insufficiency (CRI), intrauterine growth retardation (IUGR), and idiopathic short stature (ISS) has resulted in increased growth velocities. In addition, the final height of patients with Turner syndrome and CRI appears to improve with the long-term administration of GH. Final height data are still lacking in adolescents with IUGR, but height standard deviation score and final height predictions appear to improve with therapy. Based on the incomplete and inconclusive available data, one must conclude that GH treatment of children with ISS cannot be advised. The use of GH at replacement doses in children with GH deficiency has resulted in rare and generally reversible adverse effects. The long-term administration of pharmacologic GH doses to short, mostly non-GH-deficient children must, however, still be viewed with caution, as long-term complications cannot as yet be fully evaluated. GH therapy must be individualized and should be limited only to children with severe short stature or a significantly decreased growth velocity, to children under considerable stress due to their short stature, and to patients in whom low GH or low insulin-like growth factor-1 secretion might be the rate-limiting factors for growth. The cost of the medication and the inconvenience of daily GH injections to otherwise mostly healthy short children must also be taken into account.

Measuring nutritional status in children with chronic kidney disease

Children with chronic kidney disease (CKD) are at risk of protein-energy malnutrition. Existing clinical practice guidelines recognize this and recommend specific methods to assess nutritional status in patients with CKD. This review summarizes the methods for nutritional assessment currently recommended in the United States for children with CKD and details the strengths and limitations of these techniques in the clinical setting. Dietary assessment, serum albumin, height, estimated dry weight, weight/height index, upper arm anthropometry, head circumference, and the protein equivalent of nitrogen appearance are reviewed. We also describe methods for body-composition assessment, such as dual-energy X-ray absorptiometry, bioelectrical impedance analysis (BIA), total body potassium, densitometry, and in vivo neutron activation analysis, pointing out some advantages and disadvantages of each. In CKD, fluid overload is the most important factor leading to misinterpretation of nutritional assessment measures. Abnormalities in the distribution of fat and lean tissue may also compromise the interpretation of some anthropometric measures. In addition, metabolic abnormalities may influence the results obtained by some techniques. Issues specific to evaluating nutritional status in the pediatric population are also discussed, including normalization of nutritional measures to body size and sexual maturity. We stress the importance of expressing body-composition measures relative to height in a population in whom short stature is highly prevalent.

Severe bone disease and low bone mineral density after juvenile renal failure

BACKGROUND

Little is known about the late effects of juvenile end-stage renal disease (ESRD) on bone integrity. To establish clinical manifestations of metabolic bone disease and bone mineral density (BMD) in young adult patients with juvenile ESRD, we performed a long-term outcome study.

METHODS

A cohort was formed of all Dutch patients with onset of ESRD between 1972 and 1992 at age 0 to 14 years, born before 1979. Data were collected by review of medical charts, current history, physical examination, and performing dual energy x-ray absorptiometry (DEXA) of the lumbar spine and the femoral neck.

RESULTS

Clinical information was retrieved in 247 out of 249 patients. Of all of these patients, 61.4% had severe growth retardation (<-2 SD), 36.8% had clinical symptoms of bone disease, and 17.8% were disabled by bone disease. Growth retardation and clinical bone disease were associated with a long duration of dialysis. DEXA was performed in 140 out of 187 living patients. Mean BMD +/- SD corrected for gender and age (Z score) of the lumbar spine was -2.12 +/- 1.4 and of the femoral neck was -1.77 +/- 1.4. A low lean body mass was associated with a low lumbar spine and a low femoral neck BMD; male gender, physical inactivity and aseptic bone necrosis were associated with a low lumbar spine BMD.

CONCLUSION

Bone disease is a major clinical problem in young adults with pediatric ESRD. Further follow-up is needed to establish the impact of the low bone mineral densities found in these patients.