Short or tall stature is considered to be height below or above the 3rd or 97th percentile respectively.
Abnormal growth velocity, showing on serial height measurements, is also an important finding.
Growth charts based on the US NHANES study are available from www.cdc.gov/growthcharts/charts.htm. Copies of growth charts, together with height velocity and puberty charts are available at the Australasian Paediatric Endocrine Group (APEG) website, https://apeg.org.au/clinical-resources-links/growth-growth-charts/. Local Australian growth charts are currently not available.
The height of the parents should be considered in evaluating the child. Expected final height can be calculated from the parents’ heights as follows:
For boys: Expected final height = mean parental height + 6.5cm
For girls: Expected final height = mean parental height – 6.5cm
Assessment of bone age (hand/wrist) is also useful. With familial short or tall stature, bone age matches chronological age. Conversely, in a child with pathological short stature, bone age is often well behind chronological age, and may continue to fall if the disease is untreated.
The stage of puberty is relevant, as it will affect the likely final height.
A short child who is still pre-pubertal (with unfused epiphyses) is more likely to achieve an adequate final height than one in late puberty.
Causes to consider include:
Appropriate initial screening investigations can include liver and renal function tests, blood count, iron studies, thyroid function tests, coeliac disease screen, thyroid function tests, urinalysis (including pH) and karyotype. Other specialised tests may be needed, based on suspicion.
In the lower range, IGF-1 shows considerable overlap between normal and abnormal levels, especially in the setting of poor nutrition.
Small children tend to have low levels, regardless of whether growth hormone deficiency is the underlying cause. Random growth hormone levels vary widely because of pulsatile secretion and are also not a reliable test. Therefore, unless there is a clear underlying genetic or radiological diagnosis associated with clearly low IGF-1, stimulation testing is typically required to formally diagnose growth hormone deficiency and may be essential for funding of growth hormone treatment.
Investigation of stature is a specialised area and early discussion with a paediatric endocrinologist is indicated if there is clinical concern, for example, height below the 3rd percentile at age five, slow growth (crossing two percentile lines away from the median), significant height/ weight discrepancy (more than two centile lines), suspected/confirmed metabolic or genetic abnormality, or clinical evidence of malnutrition or marked obesity.
General Practice Pathology is a regular column each authored by an Australian expert pathologist on a topic of particular relevance and interest to practising GPs. The authors provide this editorial free of charge as part of an educational initiative developed and coordinated by Sonic Pathology.