Catch-up growth: possible mechanisms.

Many systemic diseases impair linear growth. If remission occurs, growth will often accelerate beyond the normal rate for age, a phenomenon termed "catch-up growth." As a result, final height is improved, although this recovery of adult stature is frequently incomplete. Two principal models have been proposed to explain catch-up growth. The first model postulates a central nervous system mechanism that compares actual body size with an age-appropriate set-point and then adjusts growth rate accordingly. However, there is recent evidence that growth inhibition in a single growth plate is followed by local catch-up growth, a finding not readily explained by the neuroendocrine model. Thus, a new model has been proposed that places the mechanism within the growth plate itself. According to this model, growth-inhibiting conditions decrease proliferation of growth plate stem cells, thus conserving their proliferative potential. Additional research is needed to determine whether the mechanisms governing catch-up growth are local, systemic, or both.