Growth retardation. Impaired height velocity.

Growth results from an increase in cell number and/or cell size. Availability of basic building materials (nutrition) and the ability to utilize them (normal organ systems) influence growth. Genes, the blueprints for the organ systems, determine growth efficiency. 1,2 Clinical assessment of growth is based on serial measurements of height and weight over time. Change occurring in relation to time is a velocity. In evaluating growth velocity, it should be noted that there may be no measurable growth during a single 3-month period in a normal child. 3 Subsequent to birth, height and weight velocity decelerate. 4,5 Height velocity decelerates from 25 cm/y to a minimal basal velocity of 5 cm/y by the third year of life. Programmed genetic variation as to what basal velocity is achieved, and how rapidly the deceleration occurs for a normal population, is graphically indicated as the percentile rankings on