A: For kids, height can seem analogous to social standing, particularly for boys. Being chosen for sports teams, seen as a leader and finding a date for a school dance can all be subtly related to a child’s height, or seemingly so, anyway. It is perhaps less of an issue for girls than for boys, socially, but for all children, maintaining normal and expected growth is part of the preventive health of childhood medicine. There can be a wider-reaching impact of establishing proper size for age. For example, many international children seeking asylum are required to have a bone age test, and the results may impact placement and allocation of resources.
Most children who are shorter than their peers are in a group called Variants of Normal – in other words, Normal. One such diagnosis is Constitutional Delay of Growth and Puberty. These children will be small compared to their peers, but they will have normal growth velocity, i.e., they are steadily getting taller, just at their own pace. There will also often be a family history of parental delayed puberty. These children should have a baseline evaluation of a thorough history and physical by a pediatrician, and have their bone age tested. Bone age is an interpretation of skeletal maturity, typically based on radiographs of the left hand and wrist or knee. A child’s bone age may or may not approximate his or her chronologic age (the actual age of the child in years according to his or her birth date). Many factors influence the progression of skeletal development, including nutrition, genetics, hormones and disease states. It is important to diagnose and treat these underlying conditions as early as possible.
Another diagnosis in this category is Familial Short Stature. These children will have short parents. The child’s height will be consistent with Midparental Height, and the child will have normal growth velocity. Midparental height is calculated differently for boys and girls. For boys – ((father’s height in inches + mother’s height in inches) + 5)/2. For girls – ((father’s height + mother’s height) — 5)/2. This child should also have a bone age test and some lab work might be recommended, as well.
The third diagnosis in the Normal Variant category is Idiopathic Short Stature. This means the child’s height is less than two standard deviations (SD) below the mean height for age, without a known medical reason. Features include normal growth velocity and normal bone age.
Most children with short stature have normal variants. Only about 5% of children referred for evaluation of short stature have an identifiable cause. The most common causes are growth hormone deficiency, hypothyroidism, celiac disease and Turner syndrome. Other causes include a variety of renal, hepatic and gastrointestinal diseases, and other genetic syndromes. Some medications can cause short stature with chronic use, including steroids, ADHD medications and seizure medications. An early evaluation and treatment are recommended for all identified causes.
Short stature is defined as a height less than the 3rd percentile for age, or more than 2 SD below the mean height for age, based on standardized growth charts – the World Health Organization growth charts for children younger than two years and the Centers for Disease Control growth charts for children older than two years. These are available at http://www.who.int/childgrowth/standards/en/ and http://www.cdc.gov/growthcharts/.
Standard well child care, which includes monitoring growth and development, may be done by a family physician or a pediatrician. Once short stature is suspected, a referral to a pediatric endocrinologist is recommended for further workup and treatment. Indications for referral include: (1) height more than 3 SD below the mean; (2) height increase of less than 2 inches per year; (3) no onset of puberty by 14 years for boys and 13 years for girls; (4) projected height of the child more than 2 SD below calculated midparental height; (5 ) bone age more than 2 SD below chronological age; and (6) diagnosis of conditions amenable to treatment with recombinant growth hormone therapy, including Turner’s Syndrome, Small for Gestational Age and Idiopathic Short Stature among others. For Idiopathic Short Stature, four years of treatment results in an increased height of 1.46 inches, and costs about $100,000. Bottom line, don’t sit at home and wonder. Please seek consultation with your child’s doctor.
Anjali Subbaswamy is a Pediatric Intensive Care Physician at UNM. Please send your questions to her at ASubbaswamy@salud.unm.edu.