The multifactorial origin of growth failure in thalassaemia.

Abstract

Growth failure in thalassaemia major (TM) has been recognised for many years, and has persisted despite major therapeutic advances. The child with TM has a particular growth pattern, which is relatively normal until age 9-10 years; after this age a slowing down of growth velocity and reduced or absent pubertal growth spurt are observed. The pathogenesis of growth failure is multifactorial. The fundamental problem is the free iron and hemosiderosis-induced damage of the endocrine glands. Additional factors may contribute to the aetiology of growth delay including chronic anaemia and hypoxia, chronic liver disease, zinc and folic acid and nutritional deficiencies, intensive use of chelating agents, emotional factors, endocrinopathies (hypogonadism, delayed puberty, hypothyroidism, disturbed calcium homeostasis and bone disease) and last but not least dysregulation of the GH-IGF-1 axis.Three phases of growth disturbances according to age of presentation are well recognised, and have different aetiologies: in the first phase growth disturbance is mainly due to hypoxia, anaemia, ineffective erythropoiesis and nutritional factors. During late childhood (second phase), growth retardation is mainly due to iron overload affecting GH-IGF-1 axis and other potential endocrine complications. Although appropriate iron chelation therapy can improve growth and development, TM children and adolescents treated intensively with desferrioxamine remain short as well, showing body disproportion between the upper and lower body segment. After the age of 10-11 years (third phase), delayed or arrested puberty is an important contributing factor to growth failure in adolescent thalassaemics, who do not exhibit a normal growth spurt. During the last decades therapeutic progress and bone marrow transplantation resulted in a prolonged life expectancy in TM patients. Growth retardation, however, continues to be a significant challenge in these individuals, often affecting their social adjustment and quality of life.