Nutrient and endocrine factors affecting impaired growth in pediatric mitochondrial diseases.

Summary: Mitochondrial diseases cause systemic failure of energy production and can manifest as various disorders of hormone production and secretion from endocrine organs. These effects can prevent normal growth in children, resulting in adults of short stature. We therefore explored the nutritional and endocrinological status of pediatric mitochondrial disease patients with impaired growth. Four Japanese patients with genetically diagnosed mitochondrial disease were studied (one male and three females, aged 4-22 years). The age of onset ranged from 0 months to 7 years, and the causal genes identified were mtDNA, PDHA1, and NARS2 (in two sibling patients). Two patients were diagnosed with small for gestational age at birth, and their current height standard deviation scores ranged from -1.9 SD to -6.4 SD. Mitochondrial diseases can present as impaired growth with dysfunction of various organs, depending on the causal gene and the degree of heteroplasmy. Our patients had demonstrated low T3 syndrome and reduced IGF1 levels, which appeared to be influenced by impaired nutritional status. These findings emphasize the need for careful monitoring of growth trajectories alongside nutritional and endocrine evaluations to improve clinical management. Learning points: Mitochondrial diseases can disrupt endocrine function involving the GH-IGF1 axis and the thyroid and gonadal systems, leading to impaired growth during childhood. Patients with early-onset mitochondrial disease tend to experience severe symptoms and pronounced growth impairment. Children with mitochondrial diseases often show low IGF1 levels, low T3 syndrome, and delayed bone age, reflecting endocrine dysfunction commonly observed in chronic systemic diseases and the further influence of suboptimal nutritional status.