Short normal stature and psychosocial disadvantage: a critical review of the evidence

Physicians and parents alike are under increasing pressure to identify and to treat short stature, but intervention implies the presence of some pathology, physical or psychological, that can be corrected. Where there is true GH deficiency, the argument for replacement is uncontroversial. It is less compelling where GH 'insufficiency' is diagnosed. In the case of the short, but otherwise normal, child the indications for therapy are even less clear. Short stature, per se, is clearly not a disease, in spite of the perception by some practitioners that the rate of growth of such children is abnormal. Short stature is, however, commonly perceived to be associated with social and psychological disadvantage, yet many of these misperceptions about short stature can be challenged. A critical review of the literature pertaining to the psychosocial correlates of short stature uncovers much flawed evidence. Most importantly, the belief, widely held by paediatricians, that short children are likely to be significantly disadvantaged, has been founded largely on data from clinic-referred samples. In such studies, children with real (or perceived) behavioural or academic problems are likely to be overly represented. Publications arising from such studies, however, inevitably lead to an increase in the demand for treatment both from and for those who previously had no such concern. In contrast, data from a well controlled, prospective population-based study suggest the essential normality of the short normal child. Parents and children alike should be reassured by these findings. In the absence of clear pathology, physical or psychological, GH therapy for short but otherwise normal children must therefore, in most cases, be deemed cosmetic, raising issues as to the ethics of so-called "plastic endocrinology".

Pubertal growth of the short normal girl

OBJECTIVES

To determine the timing, magnitude and duration of the pubertal spurt for short normal and average height girls, to compare these with Tanner's standard and to investigate predictors of pubertal growth.

METHODS

The growth of 46 short normal and 55 control girls, identified at school entry, was monitored throughout puberty. Height and weight were measured at 6-month intervals from which body mass index (BMI) was derived. Annual velocities were calculated and used to estimate the age and magnitude of peak height velocity (PHV). Age of menarche was recorded to the nearest month. Parents provided information on the child's medical and social history.

RESULTS

The mean age at PHV, the magnitude of PHV and age at menarche were similar for both groups and close to Tanner's 50th centile values. Pre-pubertal BMI predicted age at menarche for short and control girls, accounting for 17% of the variance. There was a tendency for early maturing girls of average stature to have greater PHV. However, this relationship was not observed in short girls, nor did any other variable, genetic or environmental, predict the timing or magnitude of their pubertal spurt.

CONCLUSIONS

Delayed puberty in short normal girls is unlikely and their growth during puberty is comparable to girls of average height. The pubertal variables measured remain close to Tanner's original standards for both groups, suggesting the lack of a secular trend towards earlier puberty in girls. The onset of menstruation is influenced by pre-pubertal BMI. However, the clinician should be aware that short normal girls have normal pubertal growth and that no genetic or environmental variable can predict the timing or magnitude of their growth spurt.

Normal growth in the short normal prepubertal child: the Wessex Growth Study

OBJECTIVE

The study aimed at defining the normal rate of growth for short, prepubertal children, and comparing their pattern of growth with those of average stature.

SETTING

Community based.

DESIGN

Observation of an unselected population of 109 very short, normal prepubertal children (< 3rd height centile) and 107 controls matched for age and sex (10th to 90th centile).

MAIN OUTCOME MEASURES

Height, velocity, change in height standard deviation score, from 6 to 9 years of age.

RESULTS

The absolute mean rate of growth was significantly different between groups--short normal 5.3 cm/year, controls 5.9 cm/year--corresponding to velocities on the 25th and 50th centiles, respectively. The relative growth rates, however, as shown by the changes in height standard deviation score (short normal 0.10 (SD 0.22), controls 0.10 (SD 0.24) did not differ, and each group remained close to its original 3rd and 50th centiles. Two short children showed "catch up" growth after adoption, but, otherwise, the divergence from their original height centile was the same for short normal and control children. No social or biological factors were found to predict growth rate in the short normal children, and only target height in controls. "Normal" velocity is conditional on height. Short normal children do grow more slowly than children of average stature, but they do not necessarily grow more poorly. From 6 to 9 years of age they are no more likely to fall off their height centiles than children of average stature. The value of height monitoring at this age is questioned.

Growth monitoring: testing the new guidelines

OBJECTIVE

To assess the impact of recent guidelines from the UK joint working party of child health surveillance recommending that all children be measured at age 5 and again between 7 and 9 years of age to determine how many normal school age children are likely to be referred for specialist assessment.

METHODS

The longitudinal data of 486 children measured by school nurses in a community setting were examined and compared with measurements made in a research setting by a single, skilled observer.

MAIN OUTCOME MEASURES

Number of children identified as having abnormal stature (< 0.4th or > 99.6th centile) and abnormal growth rate height standard deviation score (HSDS) change > 0.67).

RESULTS

The community survey identified seven (1.4%) children as having abnormal stature (four short, three tall), 11 (2.3%) were identified as "slow growing", and nine (1.9%) increased their HSDS by more than 0.67. These results were comparable to data collected in ideal research conditions.

CONCLUSIONS

Following the recommendations would not result in an excess number of inappropriate referrals. However, this study highlights several unresolved issues such as interobserver variability and time interval between measurements. A large scale prospective study should be considered to establish realistic and cost-effective criteria before implementation of a national screening programme.

Randomised trial of growth hormone in short normal girls

BACKGROUND

There are few data on the long-term outcome of growth-hormone treatment in short normal children. We assessed the impact of growth-hormone treatment on pubertal development and near-final height in girls.

METHODS

In a randomised controlled trial, we studied ten girls, with a mean age of 8.07 years and height 2 SDs or more below the mean for their age, and eight short untreated controls matched for age, and 20 short untreated girls who did not give consent for randomisation. The girls received either 30 IU/m2 somatropin per week as daily subcutaneous injections or no treatment. We assessed pubertal staging and height gain every 6 months.

FINDINGS

Eight treated girls completed a mean of 6.2 years' therapy. By a mean age of 16.4 years, their mean height SD score had changed significantly from -2.42 to -1.14 (p=0.008) and they were, on average, 7.5 cm taller than the girls in the control group (height SD scores did not change significantly from -2.55) and 6.0 cm taller than the non-consent group. The timing of each pubertal stage, and the age and amplitude of peak height velocity were similar for all groups.

INTERPRETATION

Growth-hormone therapy effectively increased height SD score among short normal girls started on treatment in early to mid childhood, with no untoward effect on pubertal progression.

Short stature at school entry--an index of social deprivation? (The Wessex Growth Study)

This study was carried out to examine the biological and environmental variables associated with non-organic short stature. We observed an unselected population of very short normal children (SN) and their age- and sex-matched controls (C) within the community. All 14,346 children in two health districts entering school during 2 consecutive years were screened for short stature, and those whose height lay below the 3rd centile, according to Tanner and Whitehouse standards (n = 180) were identified. Excluding 32 with pathology, five from ethnic minorities and three who refused to take part, the remaining SN children (mean height SDS-2.26) were matched with 140 age- and sex-matched controls (C) of average height (mean height SDs 0.14). Birth weight, target height and predicted adult height (based on parental height and bone age respectively), medical and social background (obtained from parental interviews), and school performance (assessed by class teachers) were the main outcome measures. Mean birth weight of the SN children was significantly lower than C (SN = 2845 g, C = 3337 g, P < 0.001). Mean mid-parental target height was also very different (SN = 162.0 cm, C = 170.9 cm, P < 0.001). Thirty-five per cent of SN children (C = 6%) had height SD scores below parental target range, though only 10% had predicted heights below target range (mean delay in bone age 0.68 years). There was a significant difference between SN children and C in the number of children in the household (SN = 2.8, C = 2.4 (P = 0.007) and in socio-economic status (P < 0.002). Many more SN children were in social classes IV and V (SN = 31%, C = 13%, P < 0.002), and had an unemployed father (SN = 22%, C = 10%, P < 0.010), highlighting the importance of environmental influences on growth. One in four SN children was judged to have serious psychosocial problems. However, the lower the socio-economic class, the less likely the SN children were to be inappropriately short for parents. Significantly more SN children were reported to have asthma (SN = 18%, C = 7%, P < 0.007) and eczema (SN = 19%, C = 5%, P < 0.001), though only the latter was significantly associated with stature below target height for both SN and C groups. Biological variables are often insufficient to explain short stature. No child, whatever the parental height, should be dismissed as normal without careful evaluation, as poor growth in the early years may be an important pointer to an adverse but potentially remediable environment.

Diurnal variation in stature: is stretching the answer?

AIMS

To investigate the extent and timing of diurnal variation in stature and to examine the effectiveness of the stretched technique in reducing the loss in height.

SETTING

A Southampton school.

DESIGN

Fifty three children, divided into two groups, were measured by two independent auxologists using a Leicester height measure. Each child was measured four times, at 0900, 1100, 1300, and 1500, using both an unstretched and a stretched technique.

OUTCOME MEASURES

Height loss after each of the three time intervals for both unstretched and stretched modes.

RESULTS

There was a clear decrease in stature during the morning, but no further loss occurred after the subjects had been up for around six hours. The mean height losses for the unstretched (stretched) modes were 0.31 cm (0.34 cm) and 0.20 cm (0.23 cm) for the periods 0900 to 1100 and 1100 to 1300, respectively, but only 0.045 cm (-0.019 cm) from 1300 to 1500. Stretching did not reduce the effects of diurnal variation, but significantly affected the recorded height by an average of 0.28 cm. There was no significant difference in reproducibility using either technique (SD 0.30 cm stretched v 0.31 cm unstretched).

CONCLUSIONS

Diurnal variation in stature may substantially affect the reliability of height data and careful consideration should be given to the timing of repeat measurements. As most height loss occurs in the morning, afternoon clinic appointments would be preferable. The standard stretched technique does not appear to reduce diurnal variation, nor does it affect precision. Measurements made using an unstretched method are recommended to avoid interobserver differences, known to occur where different observers are used.

Are short normal children at a disadvantage? The Wessex growth study

OBJECTIVE

To examine whether short stature through childhood represents a disadvantage at around 12 years.

DESIGN

Longitudinal non-intervention study of the physical and psychological development of children recruited from the community in 1986-7 after entry into primary school at age 5-6 years; this is the second psychometric assessment made in 1994-5 after entry into secondary school at age 11-13 years.

SETTING

Southampton and Winchester health districts.

SUBJECTS

106 short normal children (< 3rd centile for height when recruited) and 119 controls of average stature (10th-90th centile).

MAIN OUTCOME MEASURES

Psychometric measures of cognitive development, self concept development, behaviour, and locus of control.

RESULTS

The short children did not differ significantly from the control children on measures of self esteem (19.4 v 20.2), self perception (104.2 v 102.4), parents' perception (46.9 v 47.0), or behaviour (6.8 v 5.3). The short children achieved significantly lower scores on measures of intelligence quotient (IQ) (102.6 v 108.6; P < 0.005), reading attainment (44.3 v 47.9; P < 0.002), and basic number skills (40.2 v 43.5; P < 0.003) and displayed less internalisation of control (16.6 v 14.3; P < 0.001) and less satisfaction with their height (P < 0.0001). More short than control children, however, came from working class homes (P < 0.05). Social class was a better predictor than height of all measures except that of body satisfaction. Attainment scores were predicted by class and IQ together rather than by height. Height accounted for some of the variance in IQ and locus of control scores.

CONCLUSIONS

These results provide only limited support for the hypothesis that short children are disadvantaged, at least up until 11-13 years old. Social class seems to have more influence than height on children's psychological development.

Psychological response to growth hormone treatment in short normal children

This study provides a controlled assessment of the psychological (and physical) effects of growth hormone treatment. Fifteen short 'normal' children (height SD score < -2) have been treated with growth hormone since the age of 7/8 years. They, together with untreated short controls and average controls (10th-90th centiles), were assessed at recruitment, after three years, and after five years. Only the treated group showed a significant height increase (SD score -2.44 to -1.21 over five years). No significant differences were found at recruitment, three years, or five years in IQ, attainment, behaviour, or self esteem. Also at five years, there were no significant differences in locus of control, self perception, or parental perceptions of competence. Both short groups displayed less satisfaction with their height than the controls (p < 0.01), though all groups were optimistic of being tall adults. The treated children were no more unrealistic over final height than the untreated children. To date, no psychological benefits of treatment have been demonstrated; but nor have there been any discernible ill effects for either the treated or the untreated children.

Short stature: does it matter? A review of the evidence

Short stature is widely regarded to be a liability, but despite the importance commonly ascribed to the psychological impact of physique, there is a paucity of methodologically sound research on the topic. The question of growth hormone therapy for a short, but otherwise normal child is still controversial. The justification for such treatment will depend not only on whether a marked improvement in height can be achieved but also on whether short stature can be shown to be an appreciable handicap, either in childhood or later in life. There is some evidence, though much is anecdotal, to suggest that the short statured adult is disadvantaged both socially and economically. There are no conclusive data as yet, however, to suggest that short statured children, either before or during early adolescence have significantly lower scores on conventional psychometric testing than children of average stature. Possibly, the problems associated with short stature will only emerge in the older adolescent, but for the present, alternative, less expensive forms of treatment should be considered for those children apparently unable to cope.

Can we measure growth?

Poor installation and maintenance of height measuring equipment is a serious problem in the community. With care, however, height can be measured with sufficient precision (+/- 0.5 cm) to identify unusually short or tall stature. Height velocity, on the other hand, is liable to misinterpretation. It cannot be estimated with sufficient precision to identify abnormal growth in the short term. There is no correlation between two successive 12 month velocities. When a trend towards poor velocity is beyond all doubt then it will be apparent on the height chart alone. In addition, "poor" or "excessive" growth is conditional on the height of the child: short children do not grow at the same rate as tall. A diagnosis of abnormal growth requires long term monitoring and is best seen as a series of height measurements crossing the centiles on the height chart. Given the correct equipment and training, height or length can be measured with a fair degree of precision in the youngest of children. The earlier measurements begin, the sooner an abnormal pattern of growth will become evident. The regular monitoring of height should be standard practice and available to each and every child.

Growth and metabolic consequences of growth hormone treatment in prepubertal short normal children

Growth and the metabolic effects of growth hormone were monitored in a randomised, controlled group of 41 short, normal, prepubertal children. The treated group received daily injections of growth hormone as Genotropin (Kabi Pharmacia) 30 IU/m2/week. Fifteen children in the treated group (21 children) have completed three years of treatment, have grown significantly more than 14 (of 20) untreated children, and have a significantly greater adult height prediction. They do, however, remain leaner (body fat 13.5% in the treated group, 18% in the untreated group) and relatively hyperinsulinaemic (insulin 66.7 pmol/l in the treated group, 44.5 in the untreated group) after three years compared with untreated children. Although growth hormone appears to improve the height potential of prepubertal short normal children, the long term outcome is still uncertain.

Equipping the community to measure children's height: the reliability of portable instruments

OBJECTIVE

To compare (1) the reliability of two expensive and two inexpensive measuring instruments, suitable for use in the community and (2) the reliability of experienced compared with inexperienced observers.

DESIGN

(1) Ten children aged 5-12 years were each measured three times blindly, and in random order, by two experienced observers using four different portable instruments. (2) Four groups of four children aged 5-11 years were each measured three times blindly, and in random order by four experienced and one inexperienced measurer, using two different portable instruments.

MAIN OUTCOME MEASURES

The precision of height measurements made by different observers using different instruments, expressed in each case as the standard deviation of a single height measurement (SDshm).

RESULTS

(1) No significant difference in precision was found between instruments, SDshm ranging from 0.22-0.34 cm. The two observers using apparently the same technique, did however record significantly different absolute heights. (2) No significant difference in precision was found between experienced and inexperienced observers.

CONCLUSION

Inexpensive height measuring equipment, once accurately installed, is no less reliable than the most expensive. Inexperienced observers can, with care, measure as reliably as those with long experience. Every effort should be made, however, to ensure that the progress of individual children is monitored not only by the same observer, but on a long term basis.