Short Stature - An Approach

Introduction

Growth is an important objective parameter of the general health of a child. Short stature is a common problem encountered by practicing pediatricians. The etiology of short stature ranges from normal variants like familial short stature (FSS) & constitutional growth delay (CGD) to pathological conditions like endocrine & systemic disorders. Fortunately, the normal variants form the commoner causes and can be suggested by basic tools like anthropometric data and bone age. However, the distinction between normal & abnormal growth can be difficult at times

Short stature may sometimes be the only obvious manifestation of endocrine conditions & systemic diseases

Etiology

Short Stature - Definition

A child is considered short if:

• His height is less than 3rd percentile or 2 standard deviations below the mean height for that age.

• Even if the height is within normal percentiles but growth velocity is consistently below 25th percentile over 6-12 months of observation.

• If the patient is excessively short for the mid-parental height, though his absolute height may be within the normal percentiles.

A useful point to note: 80% of children with height less than 3SD below mean have pathologic short stature whereas 80% of children with height less than 2SD usually have normal variant short stature.

Important Terminologies & Facts While Evaluating Short Stature

Height Age: The age at which the patient's height is at the 50th percentile.

Bone age: Refers to the age at which the skeletal maturation shown in patient's radiographs is normally attained. Greulich Pyle charts are the most commonly used method, which examines the epiphyseal maturation of the hand & wrist.

Mid-parental height (MPH): The child's probable inherited growth potential can be estimated by mid-parental height percentile.

MPH range for boys = [(mother's height+13 cm)+ father's height]/2 + 8 cm

MPH range for girls = [Mother's height + (father's height- 13 cm)]/2 + 8 cm

Growth velocity/Height velocity: Observation of a child's height over a period of time or height velocity is the most important aspect of the assessment of Short Stature. Since linear growth in children occurs in small episodic increments, there are inherent inadequacies in measuring linear growth. Therefore, the determination of height velocity requires at least 6 months of observation.

Normal Growth Velocities at Different Ages

(The Growth Velocity may fall to as low as 4 cm/year just before the pubertal spurt)

A child's growth curve follows along the same channel or percentile from 2-9 years of age. The linear growth of normal infants (up to 8 months) may move to a higher or lower percentile due to a physiologic shift from intrauterine influences to the child's inherent growth potential. Crossing channels during puberty may be due to differential onset & extent of the pubertal growth spurt.

Thus, excepting infancy, the subnormal growth velocity is the hallmark of postnatal pathologic short stature.

Growth Charts

Various growth charts are available for monitoring the heights of which Tanner & Davis charts are widely used. WHO has adopted the NCHS growth charts as reference standards.

In India, the ICMR based on its multicentric study has developed reference standards for growth. This study was predominantly done in lower socioeconomic sections, therefore reflects the growth characteristics of only these sections.

Data from a study by Agarwal et al (1994) have provided reference data for well-nourished children.

Clinical Evaluation

While assessing a child with short stature, we should try to answer the following questions:

Is the child is really short?

(Children may be referred to a clinic with a mistaken view of their height). Accurate measurement of height is essential to know whether the child is short. Also because small fallacies in height measurements may get amplified while calculating growth velocities, height should be measured on a stadiometer (or similar equipment). Shoes are to be removed & the patient is made to stand straight with heels, buttocks, back & occiput touching the vertical support, the head is positioned so that the Frankfurt plane (line joining the inferior margin of the orbit to external auditory meatus) is parallel to the ground.

Supine length is taken in children below 2 years of age with an infantometer.

Is the child growing slowly?

Serial height measurements at 3-6 monthly intervals should be done to know the annual growth velocity. Retardation of growth velocity is the hallmark of postnatal pathologic short stature.

Is he a normal variant short stature?

Familial short stature (FSS)

A child who has FSS is short for the general population but is normal for the family pedigree. The birth length tends to be small. The child's projected adult height falls within the mid parental height range. The bone age & growth velocity are normal. Growth proceeds along a channel below but parallels to the 3rd percentile curve. The final height of such a child will be short. Short

Constitutional growth delay (CGD)

Typically, the child with CGD is a normal-looking child who is described as a 'late bloomer'. There is often a family history of the father being short as a child & experiencing a late pubertal spurt. The bone age is delayed & corresponds to the height age. The birth length is normal but typically slows down to fall below the 5th percentile in the first three years of life. Although puberty is delayed, the final adult height and sexual development are normal.

Silent features of Normal Variant Short Stature

Are There Any Specific Stigmata/Clues On History & Examination?

Short Stature - Investigations

If the clinical assessment is suggestive of a particular etiology for short stature, one should proceed towards doing tests to confirm the diagnosis. However, if there are no clues on history/examination, which is often the case, certain screening tests are advisable in these patients.

The following algorithm would be useful for future evaluation

Treatment

Apart from a specific treatment, according to the underlying etiology, it is important to counsel parents. Children with short stature can have psychological stress due to negative comments from relatives, peers at school, etc. The parents must be advised to bring out positive aspects of the child's personality & not to overemphasize the abnormalities of stature. The importance of diet and exercise should also be conveyed so as to achieve the maximum potential.