Snapshot A 1-year-old girl is brought to the pediatrician by her parents for a routine check-up. Her height and weight at the current visit are found to be in the 10th percentile for her age, despite having a birth height and weight in the 50th percentile. A karyotype is obtained at the request of her concerned parents, and is found to be 46,XX. Thyroid function tests reveal TSH and T4 levels within normal ranges. Introduction Overview constitutional growth delay, in which there is slowed linear growth within the first 3 years of life, is the most common cause of short stature and delay of puberty in children Epidemiology Incidence ~15% of children with short stature who are referred for endocrinologic evaluation Demographics males > females may reflect greater proportion of males who are referred for delayed growth ETIOLOGY Pathophysiology constitutional growth delay affects every organ system delays in growth and sexual development adolescents will have a normal growth spurt and normal adult height Genetics inheritance pattern may be autosomal dominant, autosomal recessive, or X-linked Presentation History usually normal birth weight and height drop in percentiles on growth curve within first 3-6 months of life and up to 3 years of age normal growth velocity resumes by 2-3 years of age Symptoms lagging growth in early childhood Physical exam immature appearance for age may be reflected in body proportions (i.e., upper-to-lower body ratio may be ↑ compared to normal) Imaging Radiograph of the hand and wrist assess skeletal maturation bone age begins to lag behind child's chronologic age during early childhood and may be delayed in adolescence Studies T4 and TSH levels within reference range in constitutional growth delay used to rule out hypothyroidism as causative factor Insulin-like growth factor 1 (IGF-1) and IGF-binding protein 3 (IGFBP-3) levels reflect production of growth hormone used to rule out growth hormone insufficiency as a causative factor Karyotype used to rule out Turner syndrome in girls Differential Cystic fibrosis key distinguishing factor chronic respiratory infections, pancreatic enzyme insufficiency, and other complications Pediatric growth hormone deficiency key distinguishing factor ↓ levels of growth hormone-dependent IGF-1 and IGFBP-3 Turner syndrome key distinguishing factor karyotype reveals partially or completely missing X chromosome (45,XO) Treatment Lifestyle reassurance growth measurements at frequent intervals (i.e., every 6 months) to establish a trajectory on a growth curve