Materials for this week:
Take-home points for short stature in childhood:
- Epidemiology: Most short stature represents familial short stature or constitutional growth delay. Incidence of growth hormone deficiency is pretty rare at 1 in 4,000 to 10,000 short children.
- What’s the clinical definition of short stature?: Short stature refers to a child who is 2 standard deviations below the mean height for age and sex (<3rd percentile).
- What are patterns of growth with familial short stature and constitutional growth delay? Familial short stature typically follows a pattern of proportional wt/ht growth along a curve below normal that starts before age 3, but with a normal bone age and, ultimately, shorter adult height. Children with constitutional growth delay (“late bloomers”) also slow down before age 3, but follow a normal rate of growth around 5th percentile and catch up later. They often have delayed puberty and below-normal bone age, but ultimately adult height in the normal range. Use mid-parental height to determine what is expected height growth (most children are within 10cm of mid-parental height).
- When to do a work-up? Work-up is recommended when the child’s height deficit is severe (<1st percentile for age), the child falls off the curve, especially after age 3 (more concerning for acquired growth hormone deficiency), the growth rate is abnormally slow (<10th percentile for bone age), predicted height differs substantially from mid-parental height, or body proportions are abnormal. Work-up includes bone age x-rays, may include labs (if suspicious for another diagnosis: CBC, ESR, renal function, calcium, phosphorus, TFTs, TTG antibody, sweat test, karyotype, IGF-1, IGFBP-3), referral to endocrinologist.
- How do we treat? Most children with short stature can be observed and offered reassurance. Evidence is lacking that short stature causes psychological harm or that there is a long-term psychosocial benefit with growth-enhancing therapy. In a few children who are very short, hormone treatment may be helpful. Human growth hormone treatment increases the growth rate, modestly increases adult height, and is mostly considered safe, but it is expensive (~$50K per inch of height!) and the long-term risk:benefit ratio for essentially healthy children remains unclear. Low-dose oral oxandrolone is a relatively inexpensive option to accelerate growth, but has not been shown to increase adult height. It’s important to support children who may be smaller than classmates; some may need extra help coping with differences based on size.