Assessment and treatment of short stature in pediatric patients with chronic kidney disease: a consensus statement

[Growth hormone therapy for children with chronic diseases]

Growth disorders are commonly observed in children suffering from chronic diseases. The pathogenesis of growth failure is multifactorial. In chronic inflammatory diseases such as juvenile idiopathic arthritis and inflammatory bowel disease, growth is also affected by pro-inflammatory cytokines. Patients with chronic diseases might also become growth hormone (GH) deficient. However, normal or increased GH secretion with reduced plasma concentrations of insulin-like growth factor-I indicate a degree of GH insensitivity in some patients. Growth damage can increase with specific treatments, especially if glucocorticoids are used. GH therapy has been used to reduce the consequences of the disease and long-term steroid therapy in these patients. In this review, it is reported the encouraging results of GH treatment in growth-retarded children with chronic diseases, both in well defined indications as well in situations still under investigation.

Determinants of height in adolescent girls with anorexia nervosa

BACKGROUND

Anorexia nervosa, a condition characterized by marked caloric restriction and low insulin like growth factor-1 levels, would be expected to cause short stature. However, this disorder is also associated with hypogonadotropic hypogonadism and high growth hormone levels. Delays in growth-plate closure from associated hypogonadism may result in a longer period of time available for statural growth with protective effects on stature. In addition, growth hormone may have direct effects on the growth plate independent of insulin-like growth factor 1 to increase statural growth.

OBJECTIVES AND METHODS

To determine the impact of undernutrition, hypogonadism, and acquired growth hormone resistance on height in adolescents with anorexia nervosa (aged 12-18 years), we examined 208 girls: 110 with anorexia nervosa and 98 controls of comparable chronological age. Sixty-three girls with anorexia nervosa and 79 controls were followed prospectively over 1 year. Mean duration of illness was 11.6 +/- 13.2 months. In a subset, overnight growth hormone sampling was performed every 30 minutes for 12 hours, and fasting insulin-like growth factor 1 levels were obtained.

RESULTS

The difference between height and target height and between predicted adult height and target height did not differ between the groups, indicating preservation of height potential. The groups had comparable bone age, but bone age was lower than chronological age in girls with anorexia nervosa. Girls with anorexia nervosa had lower insulin-like growth factor 1 levels and higher nadir growth hormone levels than those of controls. Nadir growth hormone levels predicted height SD scores and predicted adult-height SD scores in controls but not in the girls with anorexia nervosa. In girls with anorexia nervosa, insulin-like growth factor 1 and duration of illness predicted height measures. Height SD scores of <0 were more likely after 32 months of illness and at insulin-like growth factor 1 levels of <134 ng/mL. Delayed baseline bone age predicted subsequent increases in height SD scores in immature girls with anorexia nervosa.

CONCLUSIONS

Our data suggest that preservation of height potential in this cohort of girls with anorexia nervosa may be a consequence of delayed bone age. Hypogonadism may negate the deleterious effects of undernutrition on stature by allowing for a longer duration of growth.

The long-term outcomes of pediatric kidney transplantation: a single-centre experience in China

To explore the long-term outcomes of paediatric kidney transplantation and the effects of renal allograft on growth, education, employment, marriage and procreation. Twenty-seven children with ESRD received the renal allograft from 1985 to 2001. The patient and kidney survival rate, renal function, growth and employment, etc., were reviewed retrospectively. The average follow-up period was 10.3 +/- 4.4 yr. The one-, three-, five- and 10-yr graft survival rates were 96.3%, 88.9%, 81.5% and 66.7%, respectively, and the corresponding patient survival rates were 100%, 92.6%, 85.2% and 68.8%. The body weight gain was 4-10 kg in one-yr post-operative and the height increased 0-2 cm for girls and 2-5 cm for boys. A total of 44.4% of the recipients accomplished their education above junior high school. The employment rate was 46.2% in males, and 57.2% in females. Twelve patients were married. Non-adherence occurred in 30% of the recipients. Forty percent of the surviving recipients developed complications. Seven patients died. More attention should be paid to non-adherence of medications and more supports from the society are required to improve the life quality of paediatric recipients, especially in employment and education.

Growth hormone axis in chronic kidney disease

Chronic kidney disease (CKD) in children is associated with dramatic changes in the growth hormone (GH) and insulin-like growth factor (IGF-1) axis, resulting in growth retardation. Moderate-to-severe growth retardation in CKD is associated with increased morbidity and mortality. Renal failure is a state of GH resistance and not GH deficiency. Some mechanisms of GH resistance are: reduced density of GH receptors in target organs, impaired GH-activated post-receptor Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling, and reduced levels of free IGF-1 due to increased inhibitory IGF-binding proteins (IGFBPs). Treatment with recombinant human growth hormone (rhGH) has been proven to be safe and efficacious in children with CKD. Even though rhGH has been shown to improve catch-up growth and to allow the child to achieve normal adult height, the final adult height is still significantly below the genetic target. Growth retardation may persist after renal transplantation due to multiple factors, such as steroid use, decreased renal function and an abnormal GH-IGF1 axis. Those below age 6 years are the ones to benefit most from transplantation in demonstrating acceleration in linear growth. Newer treatment modalities targeting the GH resistance with recombinant human IGF-1 (rhIGF-1), recombinant human IGFBP3 (rhIGFBP3) and IGFBP displacers are under investigation and may prove to be more effective in treating growth failure in CKD.

Growth of prepubertal children on dialysis

Growth failure is a common and significant clinical problem for children on dialysis and often remains a major impediment to their rehabilitation. Early referral to a paediatric nephrology centre and appropriate management before the initiation of dialysis may significantly prevent growth deterioration. Growth in children on dialysis can be affected by nutritional, metabolic, and hormonal changes. Early diagnosis of malnutrition and aggressive management should be a priority. Gastrostomy feeding should be used when adequate oral intake to maintain normal height and weight velocity cannot be achieved. Active vitamin D metabolites should be used carefully, to prevent low-turnover bone disease. All children should have an adequate regimen of dialysis and an appropriate management of malnutrition, renal osteodystrophy, metabolic acidosis, salt wasting and anaemia, before recombinant human growth hormone (rhGH) administration is considered. The current challenge of reversing growth impairment in children on dialysis can only be achieved by optimization of their care.

Balanced calcitriol treatment to make children grow

Short stature is an important clinical problem in children with chronic kidney disease. Calcitriol is used as standard therapy to control secondary hyperparathyroidism, but its effect on linear growth remains controversial. Sanchez and He report multiple effects of calcitriol on chondrocyte proliferation and maturation that might help to clarify this controversy.

Use of rhGH in children with chronic kidney disease: lessons from NAPRTCS

We evaluated the utilization and potential benefits of recombinant human growth hormone (rhGH) in children with chronic kidney disease (CKD) and following renal transplantation in a large patient cohort. We queried the chronic renal insufficiency (CRI), dialysis, and transplant registries of the North American Pediatric Renal Trials and Collaborative Studies (NAPRTCS) to characterize the frequency of rhGH utilization, factors related to its usage, and the relationship between rhGH usage and catch-up growth. Data from 6,505, 5,122, and 4,478 CRI, dialysis, and transplant patients, respectively, was evaluated. Percentage utilization of rhGH 2 years after registry entry was 22%, 33%, and 3% in children with a height standard deviation score (SDS)<-1 and age<17 years (termed candidate group) in CRI, dialysis, and transplant patients, respectively. Multivariate logistic regression analysis showed that the likelihood of using rhGH was significantly correlated with age, gender, geographical region of residence and height category within the candidate group (p<0.01). The use of rhGH was associated with catch-up growth in 27%, 11%, and 25% of candidate CRI, dialysis, and transplant patients, respectively. In the candidate group, percentage catch-up growth was highest in children who were Tanner stage 1-2, who comprised 19.4%, 7.1%, and 25.5% of the CRI, dialysis, and transplant patients, respectively. Using multiple regression analysis, the estimated impact of rhGH on final adult height (age>19 years) was 0.80, 0.50, and 0.19 SDS, in CRI, dialysis, and transplant patients, respectively. Thus, rhGH can improve height gain in some children with CKD. The use of rhGH appears to be most effective in prepubertal children with CRI.