Model of normal prepubertal growth.

Abstract

Growth over the short term is a highly complex non-linear process. Contrasting models of short term growth have been proposed which include periodic growth cycles versus abrupt growth spurts with intervening growth arrest ('saltation and stasis'). The variability of short term growth has been characterised from a study of 46 healthy prepubertal children measured three times a week over one academic year using a combination of descriptive statistical approaches and regression modelling. Growth in childhood over one year is represented by a biphasic process comprising three to six unpredictable growth spurts, each of mean length 56 days (range 13-155 days), separated by periods of stasis (less than or equal to 0.05 cm height increment over more than seven days), each lasting a mean of 18 days (range 8-52 days) and accounting for at least 20% of the period of observation. This is superimposed on strong seasonal trends in growth with a declining growth rate over the autumn months reaching a nadir in midwinter, followed by a growth spurt in the spring. Human growth over short periods is therefore a discontinuous, irregular, and unpredictable process. (Arch Dis Child 1996;75:427-431) Keywords: growth, prepubertal, mathematical models.Studies have attempted to address this key issue by frequent measurements on a small numbers of subjects. For instance, weekly height measurements taken by parents on 10 short children were found to be described by linear trends.4 In contrast, weight gain in growth retarded infants,' catch-up growth in infants with treated coeliac disease,6 and growth in normal children78 and those with cystic fibrosis' may be described by 10 day, 60 day, and annual cycles, respectively. Using the knemometer to obtain highly accurate weekly measurements of the lower leg, minigrowth spurts occurring at 30-55 day intervals have also been described.'0 In contrast, accurate measurements of limb growth in rabbits using metal pins inserted into the tibia" have shown growth to be a continuous process. All height gained in childhood has been proposed to occur in irregular growth spurts or saltations over one day with intervening periods of no discernible growth (stases) based on studies of infants'2 and one adolescent child.'3 It has also been suggested that growth may be proceeding in a chaotic manner.2 There is therefore a wide range of putative models of human growth.Our aim in this study has been to define short term growth in a large cohort of normal children by mathematical techniques that do not impose an artificial form to the growth pattern. By gaining an insight into normal growth we may anticipate a better understanding of pathological growth and the influence of treatment, so that growth promoting treatments may be used more appropriately and effectively. Conventionally, growth in childhood is considered to be a relatively smooth and orderly process: rapid growth in infancy gives way to 'linear' growth in mid-childhood, finally culminating in the adolescent growth spurt. The familiar shape ...

The Analysis of Short-Term Growth

“…The authors concluded that their data were incompatible with the saltatory model. Similar findings were published by us [74], and further longitudinal studies have shown that only a minority of gain in stature can be said to be truly saltatory [75]. It was suggested that alternate series of saltatory events and stasis simply are a result of the assumptions of the mathematical model as the model only allows ‘increase’ (saltation), or ‘no increase’ (stasis).…”

Evaluating the effects of asthma therapy on childhood growth: principles of study design

“…Successive measurements of growth velocity are not well correlated because of the cyclical nature of growth over the short (1-yr) and longer term (2-yrs) [25,26]. Given the cyclical nature of growth, control data are essential for any study and, because of the longer-term trends in childhood growth ( fig.…”

Assessment and Management of Hypertension in Patients on Dialysis

“…Infants and young children in particular are expected to demonstrate progressive weight gain and linear growth, a process that does not proceed in a predictable linear manner. 192 Thus, it is unreasonable to expect that pediatric patients can achieve and maintain a stable dry weight. Two potential approaches to this problem have been studied: bioimpedance analysis and blood volume monitoring.…”