The Auxological and Biochemical Continuum of Short Children Born Small for Gestational Age (SGA) or with Normal Birth Size (Idiopathic Short Stature)

The evaluation of growth is an essential part of the diagnostic work-up of children attending the pediatrician's practice, particularly children referred for short or tall stature. Based on a thorough medical history together with a physical examination and various characteristics of the growth pattern, followed by a laboratory screening, the pediatrician estimates the probability of a pathological cause. With respect to growth characteristics, we have recently reported an evidence-based guideline for referring patients to a pediatrician including information on birth size, height and parental target, as well as growth faltering (deflection). This guideline has a good sensitivity to detect pathology, at a low percentage of false negatives [1]. However, only in approximately 5% of short children can a pathological cause be detected [2]. Short children in whom no pathology can be found are then subdivided into short children born small for gestational age (SGA) and children born with a normal birth size but becoming short in infancy and childhood (idiopathic short stature, ISS).There is consensus among pediatric endocrinologists about the definitions of SGA [3] and ISS [4, 5] but it has also been argued that the distinction between the two diagnostic categories is arbitrary. The distinction between SGA and ISS is based on birth weight and birth length SDS (SGA if birth weight and/or length ) and the availability of these data and the choice of the reference influence the diagnostic label.Another issue in the diagnostic classification is the way ISS can be subcategorized. In the report of a consensus workshop [4], confirmed at a recent ISS consensus meeting [5], ISS was divided into familial short stature (height SDS close to the parental target height) and nonfamilial short stature (height below the target range). For this distinction, there is uncertainty about the proper cut-off, as there are many formulas to calculate target height [6, 7]. Both subgroups can be fur