**1. Introduction**

Liver transplantation (LT) is the only effective treatment for patients with endstage liver disease (ESLD). The first successful pediatric LT was performed by Thomas Starzl in 1967 on a child with biliary atresia (BA). This marked the beginning of the use of LT in pediatric practice [1, 2]. By 2020, the total number of LTs performed was about 32,000 per year, 7–8% of which were pediatric transplant surgeries [3].

In the Russian Federation, the first pediatric LT was performed in 1997. Today, the total number of transplantations performed has exceeded 1000. The need for this type of medical care is fully satisfied in Russia. The LT program is being implemented at Shumakov National Medical Research Center of Transplantology and Artificial Organs (Shumakov Center), Russia's leading transplant center; over 100 LTs are

performed annually. Surgeries are performed in children with extremely low body mass, starting from the first months of life.

Invasive diagnostic procedures, such as needle biopsy, carry high risks for young children with low body mass. Therefore, it is an urgent task to search for markers for the development of noninvasive methods of assessing liver graft function. Given physical developmental delays in children, which are associated with hepatobiliary diseases and subsequent hormonal dysregulation, GH and IGF-1, the key elements in neurohumoral control of liver function can serve as important indicators reflecting the outcome of LT. The significance of GH and IGF-1 in pediatric LT is related to the role of hormones in the regulation of growth and body mass, their influence on hepatocyte function and immune system activity. A number of studies have shown the relationship between the GH/IGF-1 axis and recipient/graft survival [4–6].

Despite the large number of studies on the role of the GH/IGF-1 axis in children and adults, none of them are devoted to their relationship with physical development in children after LT [7–9]. The study of the role of the GH/IGF-1 axis in the neurohumoral regulation of liver graft function in young children is an important task. It may allow to assess the functional ability of the graft by noninvasive methods and will also create a vector for coming up with personalized therapy. This chapter describes the impact of the GH/IGF-1 axis on the outcome of pediatric LT (namely the clinical significance of the GH/IGF-1 axis in pediatric liver recipients) and characterizes its relationship with patients' anthropometric parameters.
