Growth in children on renal replacement therapy: a shrinking problem?

[Chronic kidney disease and growth failure: Efficacy of growth hormone treatment]

Growth failure is a frequent complication observed in children with chronic kidney disease (CKD) and correlated to increased morbidity and mortality. To achieve a normal growth in children with CKD remains challenging for pediatric nephrologists. Growth failure in the setting of pediatric CKD is multifactorial and related to an impaired sensitivity to growth hormone and to a deficiency of IGF1 (insulin-like growth factor 1). Growth failure management has improved during the last two decades and consists of correcting any nutritional and metabolic abnormalities, of an improvement of dialysis for children on end-stage renal disease, and of an administration of a supraphysiologic dose of recombinant growth hormone to overcome GH insensitivity. This article summarizes the causes, outcomes and assessment tools of growth in children with CKD as well as the management of recombinant growth hormone.

Effectiveness of growth hormone on growth and final height in paediatric chronic kidney disease

BACKGROUND

The effectiveness of rhGH on growth and final height (FH) was determined in children with CKD and kidney failure using data linkage from two national databases.

METHODS

Data on Australian children with CKD and kidney failure treated with rhGH were obtained by linking ANZDATA and OzGrow registries. The CKD cohort included children treated with rhGH prior to kidney replacement therapy (KRT). The KRT cohort consisted of children with kidney failure, some received rhGH, and some were untreated. Height standard deviation scores (Ht-SDS) were calculated with final height defined as last height recorded in girls > 16 years of age and boys > 17 years of age.

RESULTS

In the CKD group, there were 214 children treated with rhGH prior to KRT. In the KRT group, there were 1,032 children, 202 (19%) treated with rhGH and 830 (81%) untreated. Growth significantly improved in the rhGH-treated CKD group (ΔHt-SDS = +0.80 [+0.68 to +0.92]; p < 0.001) and the rhGH-treated KRT group (ΔHt-SDS = +0.38 [+0.27 to +0.50]; p < 0.001). Within the KRT cohort, final height was available for 423 patients (41%), of which 137 (32%) had been treated with rhGH. The rhGH-treated group demonstrated marginally better catch-up growth (ΔHt-SDS = +0.05 [-0.18 to 0.29]) compared to the non-rhGH-treated group (ΔHt-SDS = -0.03 [-0.16 to 0.10]; p = 0.49).

CONCLUSIONS

This large linkage study confirms rhGH is effective in improving height in children with CKD pre-KRT. However, rhGH appears to have a variable impact on growth once children have commenced KRT resulting in a marginal impact on final height.

Decreasing deceased donor transplant rates among children (≤6 years) under the new kidney allocation system

The Kidney Allocation System (KAS) was implemented in December 2014 with unknown impact on the pediatric waitlist. To understand the effect of KAS on pediatric registrants, deceased donor kidney transplant (DDKT) rate was assessed using interrupted time series analysis and time-to-event analysis. Two allocation eras were defined with an intermediary washout period: Era 1 (01/01/2013-09/01/2014), Era 2 (09/01/2014-03/01/2015), and Era 3(03/01/2015-03/01/2017). When using Cox proportional hazards, there was no significant association between allocation era and DDKT likelihood as compared to Era 1 (Era 3: aHR: 1.07, 95% CI: 0.97-1.18, P = .17). However, this was not consistent across all subgroups. Specifically, while highly sensitized pediatric registrants were consistently less likely to be transplanted than their less sensitized counterparts, this disparity was attenuated in Era 3 (Era 1 aHR: 0.04, 95%CI: 0.01-0.14, P < .001; Era 3 aHR: 0.33, 95% CI: 0.21-0.53, P < .001) whereas the youngest registrants aged 0-6 experienced a 21% decrease in DDKT likelihood in Era 3 as compared to Era 1 (aHR: 0.79, 95% CI: 0.64-0.98, P = .03). Thus, while overall DDKT likelihood remained stable with the introduction of KAS, registrants ≤ 6 years of age were disadvantaged, warranting further study to ensure equitable access to transplantation.

Pubertal development in children with chronic kidney disease

Impairment of pubertal growth and sexual maturation resulting in reduced adult height is an significant complication in children suffering from chronic kidney disease (CKD). Delayed puberty and reduced pubertal growth are most pronounced in children with pre-existing severe stunting before puberty, requiring long-term dialysis treatment, and in transplanted children with poor graft function and high glucocorticoid exposure. In pre-dialysis patients, therapeutic measures to improve pubertal growth are limited and mainly based on the preservation of renal function and the use of growth hormone treatment. In patients with end-stage CKD, early kidney transplantation with steroid withdrawal within 6 months of renal transplantation allows for normal pubertal development in the majority of patients. This review focuses on the underlying pathophysiology and strategies for improving height and development in these patients.

Growth hormone therapy in children with CKD after more than two decades of practice

This review focuses on the evidence for the efficacy and safety of recombinant human growth hormone (rhGH) therapy in children with all stages of chronic kidney disease (CKD) and at all ages. It describes the improving height prognosis for our patients both with and without rhGH; explains the underlying hormonal abnormalities that provide the rationale for rhGH use in CKD and the endocrine changes that accompany treatment; and views on who warrants treatment, with what dose, and how long for.

Patterns of growth after kidney transplantation among children with ESRD

BACKGROUND AND OBJECTIVES

Poor linear growth is a frequent complication of CKD. This study evaluated the effect of kidney transplantation on age-related growth of linear body segments in pediatric renal transplant recipients who were enrolled from May 1998 until August 2013 in the CKD Growth and Development observational cohort study.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Linear growth (height, sitting height, arm and leg lengths) was prospectively investigated during 1639 annual visits in a cohort of 389 pediatric renal transplant recipients ages 2-18 years with a median follow-up of 3.4 years (interquartile range, 1.9-5.9 years). Linear mixed-effects models were used to assess age-related changes and predictors of linear body segments.

RESULTS

During early childhood, patients showed lower mean SD scores (SDS) for height (-1.7) and a markedly elevated sitting height index (ratio of sitting height to total body height) compared with healthy children (1.6 SDS), indicating disproportionate stunting (each P<0.001). After early childhood a sustained increase in standardized leg length and a constant decrease in standardized sitting height were noted (each P<0.001), resulting in significant catch-up growth and almost complete normalization of sitting height index by adult age (0.4 SDS; P<0.01 versus age 2-4 years). Time after transplantation, congenital renal disease, bone maturation, steroid exposure, degree of metabolic acidosis and anemia, intrauterine growth restriction, and parental height were significant predictors of linear body dimensions and body proportions (each P<0.05).

CONCLUSIONS

Children with ESRD present with disproportionate stunting. In pediatric renal transplant recipients, a sustained increase in standardized leg length and total body height is observed from preschool until adult age, resulting in restoration of body proportions in most patients. Reduction of steroid exposure and optimal metabolic control before and after transplantation are promising measures to further improve growth outcome.