There may be variations of normal growth patterns. A couple of differences seen in the growth patterns of normal children include constitutional growth delay and familial (or genetic) short stature. These are not growth disorders.
In constitutional growth delay, the children are small for their age but are growing at a normal rate. The bone age is usually delayed which indicates that the skeletal maturation is younger than their age in years. The bone age is measured by taking an x-ray of the hand and wrist and comparing it with standard x-ray findings seen in children of the same age. These children tend to reach puberty later; this is manifested in the delay of the onset of sexual development and the pubertal growth spurt. They usually have a catch-up growth spurt and grow as tall as their peers upon reaching adulthood.
In familial or genetic short stature, the children are shorter because the parents are shorter. They do not have symptoms of diseases that affect their growth. These children enter puberty at a normal age and have normal growth spurts but will only reach the height similar to their parents. In both cases, both the children and their families have to be reassured that the child does not have a disease or a medical condition that is life-threatening.
Diseases of the kidneys, heart, gastrointestinal tract, lungs, bones, or other body systems might affect growth. There are signs and symptoms in these children that may point to the disease that causes the delay in growth. But the initial manifestation may show as poor growth in these kids. So, to rule out such possibilities, take your child to the pediatirician.