Constitutional growth delay is a normal variation of development where there’s a temporary delay in growth that occurs during early childhood and puberty.
You can think of it as a slowed rate of maturation, which happens normally in some people.
It’s the most common cause of short stature and pubertal delay in children and adolescents, but by adulthood, people with constitutional growth delay generally end up with normal adult heights.
Generally speaking, there are two hormonal systems that control growth - the growth hormone axis and the hypothalamic-pituitary-gonadal axis.
The growth hormone axis starts with the hypothalamus which is at the base of the brain.
The hypothalamus secretes growth hormone-releasing hormone and that stimulates the anterior pituitary gland to produce growth hormone.
Now, growth hormone affects lots of tissues - in particular it makes the body retains nitrogen leading to more muscle growth, and osteoblasts get stimulated which causes the bones to thicken.
Growth hormone also stimulates certain tissues like the liver, skeletal muscles, bones, and kidneys to produce somatomedin C, also called insulin-like growth factor 1.
Insulin-like growth factor 1 promotes cellular metabolism, prevents cell death, and helps cell divide and differentiate throughout the body.
It’s also the key hormone that stimulates the growth in length of long bones.
Now, sexual maturation is under the control of the hypothalamic-pituitary-gonadal axis.
This axis also starts with the hypothalamus which releases Gonadotropin-releasing hormone, or GnRH which stimulates the anterior pituitary to produce the gonadotropin hormones: luteinizing hormone, or LH, and follicle-stimulating hormone, or FSH.