AssessmentsConstitutional growth delay
Constitutional growth delay
USMLE® Step 2 style questions USMLE
A 14-year-old boy comes to the clinic because he is concerned that he is the shortest student in this grade. His father states that both he and the patient’s mother were “late bloomers” and did not achieve average height until 17 years of age. Past medical history is unremarkable. The growth curve reveals that the patient was at the 50th percentile for height and weight at birth, experienced a gradual deceleration in growth velocity until 3 years of age, and has maintained a normal growth velocity at the 3rd percentile curve since. Physical examination reveals slightly immature physical appearance for acne and Tanner stage 2 genitalia and pubic hair. Which of the following is the most likely diagnosis?
Contributors:Sam Gillespie, BSc
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.
Now, the amount of hormone that gets produced by this axis varies over a person’s lifetime, and that affects the development of the sex organs, as well as the appearance of secondary sexual characteristics.
During puberty, there’s increased GnRH production and increased levels of FSH and LH, and that triggers the onset of sexual maturity.
The stages of sexual maturity that a person goes through are referred to as the Tanner scale.
The Tanner scale centers on two, independent criteria: the appearance of pubic hair in both sexes; and the increase in testicular volume and penile size and length in males, and breast development in females.
There are five stages: In stage 1, the prepubertal stage, no pubic hair is present in either sex.
Males have a small penis and testes. Females have a flat-chest.
In stage 2, pubic hair appears and there’s a measurable enlargement of the testes; and breast buds appear.
In stage 3, pubic hair becomes coarser; the penis begins to enlarge in both size and length; and breast mounds form.
In stage 4, pubic hair begins to cover the pubic area; the penis begins to widen; and breast enlargement continues to form something called a “mound-on-mound” contour.
In stage 5, pubic hair extends to the inner thigh; the penis and testes have enlarged to adult size; and the breast takes on an adult contour.
Constitutional growth delay is not a disorder but a normal variation in the rate of growth.
Growth charts are often used to track the development of children, and they usually have age on the X, or horizontal axis and head circumference, weight, or height on the Y, or vertical axis.
The children typically have normal height and weight at birth but during the first few years of life their growth rate declines.