What does a bone age that is less than chronological age indicate in children?

A bone age that is less than chronological age typically indicates a condition known as constitutional growth delay. This phenomenon occurs when a child's physical development is delayed compared to their peers, but they are otherwise healthy. These children often reach their growth potential as they age, eventually achieving a normal height in adulthood.

In constitutional growth delay, the growth plates in the bones mature at a slower rate, resulting in a bone age that appears younger than the child's chronological age. This is a common variant in normal development, particularly in boys.

In contrast, other conditions like growth hormone deficiency, Turner syndrome, and precocious puberty present differently. Growth hormone deficiency can also lead to delayed bone age, but it is usually accompanied by other growth-related issues. Turner syndrome is associated with other specific clinical features and often includes short stature but can show variations in bone age. Precocious puberty leads to an advanced bone age due to early activation of the growth plates, which is the opposite of what is seen in constitutional growth delay.

Overall, in a scenario where the bone age is significantly less than the chronological age, constitutional growth delay is the most likely cause, as it represents a benign variation in growth without the associated complications seen in the other conditions.