Linear Growth after Pediatric Kidney Transplant: Factors Influencing Catch-Up Growth in a Retrospective Cohort

Background: Children with chronic kidney disease often face growth deficits due to electrolyte, nutritional, and hormonal issues. Kidney transplantation (KT) can enhance growth, but catch-up growth (CUG) to expected height for age is not always achieved. Understanding post-transplant (PT) growth is vital for optimizing interventions, such as growth hormone (GH) use, which is limited in Brazil. Therefore, this study aims to identify the prevalence and factors associated with sufficient CUG in children who underwent KT. Methods: This retrospective cohort study at a tertiary pediatric nephrology center in Brazil included patients under 18 who had KTs between 2010 and 2023. Data were collected from medical records. Sufficient CUG was defined as an increase in height standard deviation score (SDS) ≥ 0.5 SD from pre-transplant to 2 years PT. Weight, height SDS and BMI-for-height-age SDS were compared using ANOVA for repeated measures, followed by Bonferroni post hoc tests for normally distributed variables, and the Friedman test with Bonferroni-adjusted significance level post hoc analysis for non-normal variables. Logistic regression was used to identify pre-transplant factors associated with CUG, with significance set at 5%. Results: The sample included 27 patients (mean age 9.4 years, 81.5% male). Dialysis modalities included peritoneal (44.4%), hemodialysis (29.6%), and both (18.5%). Uropathy was the main etiology (51.9%). None used GH during follow-up. Preemptive transplants accounted for 7.4%. KT significantly improved weight (p<0.001), height SDS (p<0.024), and BMI-for-height-age (p<0.002), with more pronounced gains in the first 6 months. Improvements stabilized between 6 months and 1 year. Among the 22 patients who followed up to 2 years, sufficient CUG was observed in 18.2%. Univariate and multivariate analyses found no significant associations between the pre-transplant characteristics and CUG. Conclusion: KT significantly improved height and weight, though only a small proportion achieved sufficient CUG after 2 years. Larger studies are needed to identify factors involved in CUG and optimize interventions.