Approach to short stature: Clinical sciences

Short stature in children refers to a height more than two standard deviations below the average of other children of the same age and biological sex. Short stature is often a variant of normal growth, but can also be caused by underlying conditions. Now, important types of non-pathologic short stature include constitutional delay of growth and puberty and familial short stature.

On the flip side, important causes of pathologic short stature include skeletal conditions, malnutrition, chronic conditions, as well as endocrine or genetic disorders.

Your first step to evaluate a child with short stature is to perform a history and physical exam, including measuring height and weight.

History may reveal family members who were “late bloomers”, and one or both parents may also have short stature. In some cases, caregivers could report a history of chronic conditions, like recurrent infections or known congenital heart disease; as well as symptoms that could indicate systemic illness, like fever, vomiting, diarrhea, or fatigue. Be sure to obtain dietary and birth history as well. Then, physical exam could reveal findings suggestive of an underlying condition, such as dysmorphic features, pallor, heart murmurs, skin lesions, or lymphadenopathy.

Next, be sure to measure their weight, in case nutritional causes are being considered; as well as their height, since the suspected growth failure may actually be due to an inaccurate measurement. If your patient is under 2 years of age, measure their length in a supine position; and if your patient is over 2, measure their height in a standing position. Next, plot your patient’s height on a standardized growth chart that’s appropriate for the child's age and sex, and assess their height-for-age by comparing their growth against previous growth measurements. If the height is more than 2 standard deviations below the mean, or if the height has crossed 2 major percentile lines, diagnose short stature.

Once you diagnose short stature, assess the growth chart for decreased height velocity in centimeters per year. For children 2 to 4 years of age, this is less than 5.5, while for children 4 to 6 years, this is less than 5. Then, for biological males greater than 6 years through puberty, this is less than 4; and for biological females greater than 6 years through puberty, it’s less than 4.5.

Here’s a clinical pearl! Infants who are born preterm or small for gestational age, or SGA, are expected to catch up to peers by 2 years of age. This means you should plot the height of these infants by correcting for gestational age until a child is 2 years old. After 2 years old, most children, including those born preterm or SGA, don’t cross percentile lines on the growth chart. So, you should always evaluate any child who meets the criteria for short stature after 2 years of age, regardless of birthweight or gestational age.

Okay, now let’s use the history and physical, and height velocity, to determine next steps. If there are no signs or symptoms suggesting an underlying condition, and height velocity is normal, you should consider non-pathologic short stature, and obtain an X-ray of the left hand to determine bone age. Bone age can be determined by comparing X-ray images of the patient’s left hand and wrist to a standardized set of reference X-rays, matching it to the corresponding age in order to assess skeletal maturation.

If the X-ray findings reveal a delayed bone age, diagnose constitutional delay of growth and puberty. These children are “late bloomers”, who often have delayed onset of puberty. The growth chart will typically demonstrate a normal birth weight, followed by decreased height velocity within the first 3 to 5 years of age. These children then grow at a pre-pubertal height velocity during the average age of the pubertal growth spurt, resulting in a significantly decreased height percentile during adolescence. However, they typically achieve a normal adult height.

On the flip side, if the X-ray reveals that the bone age is not delayed, your next step is to calculate the midparental height. Use the midparental height to predict a child’s growth potential, based on the parents’ height. Most children will achieve an adult height within 10 centimeters of the midparental height. To calculate mid-parental height, first add the mother’s height in centimeters to the father’s height in centimeters; then, add 13 centimeters for biological males, or subtract 13 centimeters for biological females. Finally, divide the total by 2. You can then compare the result against the child’s estimated adult height on the growth chart.

If the midparental height is within 10 centimeters of your patient’s estimated adult height, then adult short stature can be predicted, so diagnose familial short stature. The growth chart of a child with familial short stature will show a height-for-age consistently tracking at or below the 3rd percentile, with normal height velocity, and a proportionate weight-for-age. Alternatively, if adult short stature is not predicted by midparental height, you should consider pathologic short stature.

Okay, now let’s go all the way back. If the history and physical exam reveal signs or symptoms suggesting an underlying condition; or if height velocity is decreased, you should consider pathologic short stature! In these individuals, your first step is to assess skeletal growth by measuring your patient’s age-related upper-to-lower body segment ratio and arm span-to-height ratio. If either ratio is abnormal, this indicates disproportionate skeletal growth, so order a skeletal survey. If the skeletal survey identifies skeletal dysplasia, you can diagnose a skeletal disorder, such as spondyloepiphyseal dysplasia or achondroplasia.

On the other hand, if your patient has proportionate skeletal growth, your next step is to find an underlying cause of short stature. Begin your workup by ordering several labs, including a CBC with differential; a CMP; an ESR; a CRP; thyroid function tests, including TSH and free T4; a TTG IgA and total IgA; IGF-1 and IGFBP-3 levels; a dexamethasone suppression test; a urinalysis; and, finally, if your patient is biologically female, a karyotype.