Constitutional delay of growth and adolescence. Results of short-term and long-term treatment with GH

Targeted resequencing of the pericentromere of chromosome 2 linked to constitutional delay of growth and puberty

Constitutional delay of growth and puberty (CDGP) is the most common cause of pubertal delay. CDGP is defined as the proportion of the normal population who experience pubertal onset at least 2 SD later than the population mean, representing 2.3% of all adolescents. While adolescents with CDGP spontaneously enter puberty, they are at risk for short stature, decreased bone mineral density, and psychosocial problems. Genetic factors contribute heavily to the timing of puberty, but the vast majority of CDGP cases remain biologically unexplained, and there is no definitive test to distinguish CDGP from pathological absence of puberty during adolescence. Recently, we published a study identifying significant linkage between a locus at the pericentromeric region of chromosome 2 (chr 2) and CDGP in Finnish families. To investigate this region for causal variation, we sequenced chr 2 between the genomic coordinates of 79-124 Mb (genome build GRCh37) in the proband and affected parent of the 13 families contributing most to this linkage signal. One gene, DNAH6, harbored 6 protein-altering low-frequency variants (< 6% in the Finnish population) in 10 of the CDGP probands. We sequenced an additional 135 unrelated Finnish CDGP subjects and utilized the unique Sequencing Initiative Suomi (SISu) population reference exome set to show that while 5 of these variants were present in the CDGP set, they were also present in the Finnish population at similar frequencies. Additional variants in the targeted region could not be prioritized for follow-up, possibly due to gaps in sequencing coverage or lack of functional knowledge of non-genic genomic regions. Thus, despite having a well-characterized sample collection from a genetically homogeneous population with a large population-based reference sequence dataset, we were unable to pinpoint variation in the linked region predisposing delayed puberty. This study highlights the difficulties of detecting genetic variants under linkage regions for complex traits and suggests that advancements in annotation of gene function and regulatory regions of the genome will be critical for solving the genetic background of complex phenotypes like CDGP.

An approach to constitutional delay of growth and puberty

Constitutional delay of growth and puberty is a transient state of hypogonadotropic hypogonadism associated with prolongation of childhood phase of growth, delayed skeletal maturation, delayed and attenuated pubertal growth spurt, and relatively low insulin-like growth factor-1 secretion. In a considerable number of cases, the final adult height (Ht) does not reach the mid-parental or the predicted adult Ht for the individual, with some degree of disproportionately short trunk. In the pre-pubertal male, testosterone (T) replacement therapy can be used to induce pubertal development, accelerate growth and relieve the psychosocial complaints of the adolescents. However, some issues in the management are still unresolved. These include type, optimal timing, dose and duration of sex steroid treatment and the possible use of adjunctive or alternate therapy including: oxandrolone, aromatase inhibitors and human growth hormone.

Adult height in children with short stature and idiopathic delayed puberty after different management

By retrospectively collecting data from nine Italian centres of pediatric endocrinology, we assessed the different management and final outcome of children with short stature and idiopathic delayed puberty. Data were obtained in 77 patients (54 males, 23 females) diagnosed and followed-up in the various centres during the last 15 years. Inclusion criteria were short stature at initial observation and idiopathic delayed puberty diagnosed during follow-up. At first observation, age was 13.8 +/- 1.0 years and height standard deviation score (SDS) was -2.6 +/- 0.6 in males. In females age was 13.1 +/- 0.9 years and height SDS -2.6 +/- 0.4. Local diagnostic and therapeutic protocols included testing for growth-hormone deficiency (six centres) and treatment in case of deficiency or, in the remaining centres, testosterone or no treatment in males, and no treatment in females. At diagnosis, both in males and in females, the auxological features (height SDS, target height SDS and bone age delay) were similar in the patients treated with growth hormone, testosterone or not treated. Overall 32 patients received growth hormone (25 males, 7 females), 33 no treatment (17 males, 16 females) and 12 testosterone. There was no difference in the adult height of males and females in the different treatment groups. In males there were no differences between adult and target height SDSs (growth hormone-treated 0.31 +/- 0.79, untreated 0.10 +/- 0.82, testosterone-treated 0.05 +/- 0.95), between adult and initial height SDSs (growth hormone-treated 1.70 +/- 0.93, untreated 1.55 +/- 0.92, testosterone-treated 1.53 +/- 1.43) and percentage of subjects with adult height above target height. In females, there were no differences between adult and target height SDSs (growth hormone-treated -0.49 +/- 1.13; untreated 0.10 +/- 0.97) and between adult and initial height SDSs (growth hormone-treated 1.76 +/- 0.92; untreated 1.77 +/- 0.98), whereas a significantly higher percentage of patients remained below target height in the growth hormone-treated group (6/7, 85.7% vs 5/11, 31.3%) (P = 0.02). In conclusion, the diagnostic and therapeutic management of the patients with short stature and delayed puberty is different among Italian pediatric endocrinologists. Our data do not support the usefulness of growth-hormone therapy in improving adult height in subjects with short stature and delayed puberty, particularly in the female sex.

High dose growth hormone treatment induces acceleration of skeletal maturation and an earlier onset of puberty in children with idiopathic short stature

BACKGROUND

Long term growth hormone (GH) treatment in children with idiopathic short stature (ISS) results in a relatively small mean gain in final height of 3-9 cm, which may not justify the cost of treatment. As it is unknown whether GH treatment during puberty adds to final height gain, we sought to improve the cost-benefit ratio, employing a study design with high dose GH treatment restricted to the prepubertal period.

AIMS

To assess the effect of short term, high dose GH treatment before puberty on growth, bone maturation, and pubertal onset.

METHODS

Five year results of a randomised controlled study are reported. Twenty six boys and nine girls were randomly assigned to a GH treatment group (n = 17) or a control group (n = 18). Inclusion criteria were: no signs of puberty, height less than -2 SDS, age 4-8 years for girls or 4-10 years for boys, GH concentration >10 micro g/l after provocation, and normal body proportions. To assess GH responsiveness, children assigned to the GH treatment group received GH treatment for two periods of three months (1.5 IU/m2/day and 3.0 IU/m2/day), separated by three month washout periods, during the first year of study. High dose GH treatment (6.0 IU/m2/day) was then started and continued for at least two full years. When puberty occurred, GH treatment was discontinued at the end of a complete year's treatment (for example, three or four years of GH treatment).

RESULTS

In response to at least two years on high dose GH treatment, mean (SD) height SDS for chronological age increased significantly in GH treated children from -2.6 (0.5) to -1.3 (0.5) after two years and -1.4 (0.5) SDS after five years of study. No changes in height SDS were observed in controls. A rapid rate of bone maturation of 3.6 years/2 years in treated children compared to 2 years/2 years in controls was observed in response to two years high dose GH treatment. Height SDS for bone age was not significantly different between groups during the study period. GH treated children entered into puberty at a significantly earlier age compared to controls.

CONCLUSIONS

High dose GH treatment before puberty accelerates bone age and induces an earlier onset of puberty. This may limit the potential therapeutic benefit of this regimen in ISS.

Effect of growth hormone treatment on adult height of children with idiopathic short stature. Genentech Collaborative Group

BACKGROUND

Short-term administration of growth hormone to children with idiopathic short stature results in increases in growth rate and standard-deviation scores for height. However, the effect of long-term growth hormone therapy on adult height in these children is unknown.

METHODS

We studied 121 children with idiopathic short stature, all of whom had an initial height below the third percentile, low growth rates, and maximal stimulated serum concentrations of growth hormone of at least 10 microg per liter. The children were treated with growth hormone (0.3 mg per kilogram of body weight per week) for 2 to 10 years. Eighty of these children have reached adult height, with a bone age of at least 16 years in the boys and at least 14 years in the girls, and pubertal stage 4 or 5. The difference between the predicted adult height before treatment and achieved adult height was compared with the corresponding difference in three untreated normal or short-statured control groups.

RESULTS

In the 80 children who have reached adult height, growth hormone treatment increased the mean standard-deviation score for height (number of standard deviations from the mean height for chronologic age) from -2.7 to -1.4. The mean (+/-SD) difference between predicted adult height before treatment and achieved adult height was +5.0+/-5.1 cm for boys and +5.9+/-5.2 cm for girls. The difference between predicted and achieved adult height among treated boys was 9.2 cm greater than the corresponding difference among untreated boys with initial standard-deviation scores of less than -2, and the difference among treated girls was 5.7 cm greater than the difference among untreated girls.

CONCLUSION

Long-term administration of growth hormone to children with idiopathic short stature can increase adult height to a level above the predicted adult height and above the adult height of untreated historical control children.

Comparison of final heights of growth hormone-treated vs. untreated children with idiopathic growth failure

We measured adult heights (Ht) of 94 healthy GH-sufficient children (peak GH > 10 ng/mL, polyclonal RIA) whose Ht at presentation were more than 2 SD below the mean for chronological age, with normal weight-to-Ht ratios, normal body proportions, and pathologic growth velocity for chronological age. Group 1 (n 36, 6 females) received standardized doses (0.3 mg/kg x week) of GH (mean duration = 41 months), while group 2 (n = 58, 17 females) received no treatment. Our conclusion was that the mean final Ht SD score in the GH-treated group (-1.5) was significantly greater than in the untreated group (-2.1); P < .001. Genetic predisposition to short stature was evident in both groups: the midparental Ht SD score was -1.1 in the treated and -1.0 in the untreated group. Midparental Ht was met or exceeded by 42% of the GH-treated group but only 15% of the untreated group. Final Ht was not significantly different from predicted Ht, except from GH-treated girls, who exceeded their predicted Ht. Although the mean Ht gains (6.8 cm in girls and 3 cm in boys) were modest and variable, GH treatment provided significantly better Ht outcomes for the majority of children with idiopathic growth failure.

Unfavorable effects of growth hormone therapy on the final height of boys with short stature not caused by growth hormone deficiency

A group of 18 boys with non-growth hormone (GH)-deficient short stature without GH therapy (group A) and another group of 9 boys with non-GH-deficient short stature with GH therapy in doses of 0.5 IU (0.17 mg)/kg per week administered 5 to 6 times weekly (group B) were observed until they reached their final height. The mean duration of GH therapy was 4.2 years (range 3.2 to 5.0 years). These two groups were matched with respect to their standard deviation score (SDS) for bone age at the start of observation. Mean +/- SD of the final height for group A and group B was 162.0 +/- 5.4 cm and 154.2 +/- 4.2 cm, respectively. During the prepubertal period, height SDS for bone age of these two groups was not affected by GH therapy. During the pubertal period, however, height SDS for bone age remained constant for group A but decreased gradually for group B. Our observation indicates that for boys with non-GH-deficient short stature GH therapy does not improve height SDS for bone age during the prepubertal period, and in fact reduces it during the pubertal period, possibly resulting in a shorter final height than might have been attained naturally.

Final height outcome in both untreated and testosterone-treated boys with constitutional delay of growth and puberty

The present retrospective study is based on a historical follow-up of 49 boys with constitutional delay of growth and puberty (CDGP) who went into puberty spontaneously (27 cases) or induced by depotestosterone treatment, 50 mg/ month for 6 months (22 cases). At the time of puberty the two groups of boys were similar in bone age, height deficiency, target height (TH) and had similar predicted final heights (FH). Their FH was measured and compared with TH calculated from measured parents' heights. FH did not significantly differ between the untreated boys and those treated. In the two groups of patients FH was similar and corresponded to both TH and height predicted at puberty onset. This study confirms that most boys with CDGP spontaneously attain a FH within the target range (24/27 cases). A short-term and low dose course of depotestosterone can be used without adverse effects on FH. The Bayley-Pinneau method can be generally considered accurate for predicting FH in CDGP, although significant discrepancies between FH and predicted height have been recorded in a fair number of both untreated and treated boys.

Spontaneous growth and response to growth hormone treatment in children with growth hormone deficiency and idiopathic short stature

Isolated idiopathic growth hormone deficiency (GHD) and idiopathic short stature (ISS) can be difficult to distinguish, but the therapeutical consequences are different. In this report the data on final height of untreated and treated children with GHD and ISS are reviewed. Untreated GH-deficient individuals who underwent spontaneous puberty (22 male, 14 female patients) reached a mean final height of 4.7 SD (range 3.9 to 6.0) below the population's mean. If puberty was induced (19 male patients), mean final height SD score (SDS) was -3.1. Traditional regimens of GH administration (2-4 injections/wk) in 236 children (184 boys, 52 girls) with GHD and spontaneous puberty resulted in a final height SDS of -2.8 (range -1.5 to -4.7). In 190 children in whom puberty was induced (139 boys, 51 girls) mean final height was -1.6 (range - -1.1 to -2.4). The mean gain in final height SDS is therefore estimated at 1.5-2.0 in average cases, and 3.5 in extreme cases. Preliminary data suggest that on present regimens mean final height may approach target height. In untreated boys with ISS the mean final height was 2-5 cm lower than that predicted before puberty, whereas in girls it was almost equal to the prediction. After GH treatment the mean final height was 0.4-3.0 cm higher than the predicted adult height, which results in an average net gain in final height SDS of approximately 0.5-0.8 (3-5 cm).

Growth hormone treatment of children with neural tube defects: results from 6 months to 6 years

OBJECTIVE

Patients with neural tube defects (myelomeningocele) have severe growth retardation, and treatment with recombinant human growth hormone (rHGH) for 6 months accelerates growth velocity. We examined patients treated for longer periods to determine whether accelerated growth persists, and whether patients demonstrated to be growth hormone deficient have a greater response to rHGH therapy.

METHODS

We retrospectively evaluated the growth rate and length standard deviation score (SDS) of 22 patients in response to treatment with 0.3 mg/kg per week of rHGH for 7 to 72 months. Nine of 22 patients were growth hormone deficient (nocturnal and provocative growth hormone responses < 7 ng/ml). Treatment success was defined as an increase of length SDS of > 0.2 SD per year.

RESULTS

Fourteen patients (64%) had treatment successes, and eight had treatment failures. Length SDS improved from a pretreatment value of -2.9 (+/- 1.2) to the most recent length SDS of -1.9 (+/- 1.4) (p < 0.001). The growth rate was significantly increased through year 4 of treatment. The annualized growth rate after 6 months of rHGH treatment was significantly different for the success and failure groups (11.0 +/- 2.6 cm/yr vs 5.1 +/- 3 cm/yr, p < 0.001). The annualized 6-month growth rate during treatment was related to the probability of treatment success.

CONCLUSION

Treatment with rHGH significantly improves the growth rate and length SDS of children with neural tube defects. The 6-month annualized growth velocity during treatment was predictive of long-term treatment response. The effect on adult stature is unknown.

Final height and predicted height in boys with untreated constitutional growth delay

We report on 49 boys with constitutional growth delay (CGD) who were initially seen in our clinic at a mean chronological age of 13.3 years (range, 7.3-16.4) and a bone age of 11.1 years (range, 6.0-13.5). All were below the 5th height percentile for chronological age. A positive family history with delayed growth and puberty in one or both parents could be elicited in 75%. All 49 patients were re-examined at a mean age of 22.9 years (range, 20.4-31.2). Measured final height was 171.3 cm (range, 161.2-181.7), which was slightly, but significantly lower than mean target height of 173.0 cm. Final height expressed as standard deviation score (SDS) of a male adult population standard was -1.0 (range, -2.4 to 5), also significantly lower than initial height SDS related to bone age (SDSBA) of -0.5 (range, -1.6 to 2). If related to target height (Tanner), final height was found to correlate positively with the initial bone age deficit and the initial height SDSBA. Observed final height was also compared with the predicted adult height by the methods of Bayley-Pinneau (BP), Tanner-Whitehouse Mark II (TW II) and Roche-Wainer-Thissen. Regression equations between all three prediction methods and final height showed an excellent correlation (P < 0.0001). However, only by the BP method was predicted height very close to and no different from measured final height (paired t-test). Despite this, final height in 16 of 49 patients (32.6%) differed by more than 5.0 cm from BP predicted height.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of two years of growth hormone treatment in short, slowly growing non-growth hormone deficient children

Thirty-two short, slowly growing prepubertal children with normal GH levels (after clonidine stimulation and overnight sampling) were treated with GH hormone for 2 consecutive years at a dose of 0.1 IU/kg/day s.c. Fifteen similar children were followed for 2 years without therapy (controls). Height velocity increased in our treated group from 3.8 +/- 0.9 cm/yr to 7.3 +/- 1.3 cm/yr and 7.1 +/- 0.9 cm/yr in the first and second years of therapy, with 85.7% and 87.5% of our patients growing > 2 cm/yr above baseline. Height SDS changed from -2.4 +/- 0.4 to -2.0 +/- 0.7 in the first year and to -1.8 +/- 0.5 during the second year of treatment, while bone ages increased at a slightly higher rate than chronological ages. An increase in the final height predictions of our patients during therapy was noted. Height velocity increment in the control group was not significant and height SDS of this group did not change. GH therapy in short, slowly growing non-GH deficient children seems to be effective and safe in the short term; however, its efficacy in increasing the final height of this group of patients is still undetermined.

Investigation of delayed puberty

Delayed puberty is defined arbitrarily on the basis of statistical consideration, when no signs of puberty have occurred at 2.0 SD (13.4 years in girls and 13.8 in boys) above the mean chronological age for the onset of puberty. The vast majority of these patients have no endocrine abnormality and their pubertal development and growth spurt are simply consequences of primary delay (constitutional delay of growth and puberty (CDGP)) or secondary delay due to a chronic disease of childhood, such as asthma. However, a small proportion may have pathological causes of delayed puberty which must be careful identified as specific management may be required. Associated with delayed puberty, the growth spurt is always delayed which is why the condition is described as delayed growth and puberty. Short stature and lack of sexual development may lead to emotional and social difficulties and in some patients their consequences can persist when 'normal' height and full sexual maturation are attained. Recent data also suggest that a delay in the 'tempo' of pubertal maturation may interfere with the normal bone accretion occurring during puberty, later causing osteoporosis. Such findings suggest that a new approach in delayed puberty may be necessary not only for psychological reasons but also for optimizing bone mass accretion.

Long term treatment with low dose testosterone in constitutional delay of growth and puberty: effect on bone age maturation and pubertal progression

We compared the effects of long term low dose treatment with testosterone on pubertal growth and sexual development in boys with constitutional delay of growth and puberty (CDGP). We treated 24 boys with intramuscular monthly injections with low dose testosterone enanthate (33-50 mg) for 20 months, at a chronological age of 14.5 +/- 1.0 years and SDS height of -3.31 and compared their response to a group of 14 control boys. Treated patients showed an earlier and significant increase in height velocity compared to controls, 10.1 vs 4.0 cm/year, while the latter group showed their growth spurt twelve months later. Both groups showed an initial acceleration in bone age without impairment of predicted adult height. During the first 12 months of treatment the increment of testicular volume in the treated patients was slightly slower than controls; however the earlier the puberty, the slower the testicular increment compared to controls. We conclude that treatment of boys with constitutional delay of growth with low dose testosterone is effective in improving their height velocity without impairment of predicted final height. Progression of testicular volume during treatment in some patients is more delayed; however, after treatment it increased normally.

Predictive factors in the determination of final height in boys with constitutional delay of growth and puberty

Seventy-eight patients who had constitutional delay of growth and puberty were included in a retrospective study to determine whether, at the time of first evaluation, any predictive features could suggest final height outcome. Mean chronologic age was 14.3 years (range, 12 to 18 years), and all were either prepubertal or in an early stage of pubertal maturation (4 ml testicular volume). Initial mean (+/- SD) height standard deviation score was -2.74 (+/- 0.71); 85% had a relatively short spine compared with subischial leg length. Mean (+/- SD) growth rate was 4.8 (+/- 1.6) cm/year, and epiphyseal maturation was delayed by 2.4 (+/- 1) years. Sixteen boys were treated with a sustained-action preparation of testosterone (50 mg monthly for 3 to 4 months), six with oxandrolone (1.25 mg daily for a mean of 4 months), and one with both drugs in sequence. At final height attainment, 58% of the boys failed to achieve their full genetic potential; among the remaining 42%, only 0.7% attained a final height above corrected mid-parental height. The relative disproportion between the segments had no significant change at final height attainment. Regression analysis showed that final height impairment (the difference between mid-parental height and final height) was negatively influenced by standing height and growth velocity when initially evaluated and positively by the degree of segmental body proportion; that is, patients who were taller, were growing at a faster rate, and who had a major degree of segmental body disproportion with a short spine and long leg length attained a final height closer to their mid-parental height, irrespective of the degree of delayed epiphyseal maturation. Neither testosterone nor oxandrolone administered during early puberty modified final height attainment or segmental proportion. We conclude that a late onset in the timing of puberty seems to be deleterious to spinal growth and consequently to final height attainment. An alternative diagnosis should be sought among patients with features of constitutional delay of growth and puberty who do not have a significant degree of body disproportion. In these patients, as well as in those who are extremely short, who have a poor growth rate, or who have an unfavorable genetic potential, an alternative therapeutic approach may be required.

Effect of growth hormone therapy on final versus predicted height in short twelve- to sixteen-year-old boys without growth hormone deficiency

The effect of growth hormone therapy on final height in 28 short boys without growth hormone deficiency was evaluated retrospectively. The boys had received growth hormone for at least 2 years and were close to final height when therapy was stopped. The mean estimated final height was very close to that predicted from the pretherapy bone age. The fact that bone age advanced a mean of 4.9 years during a mean of 3.5 years of therapy may account for the lack of effect on final height.

Diagnostic evaluation of short children with height 3 SD or more below the mean

Most children who are more than 2 SD below the mean in height (less than third percentile) have no definable cause and are considered short-normal, but for children who are 3 SD below the mean (the lowest 0.13%), the prevalence of organic disease is known to be considerably greater. To better define the frequency of different diagnoses in this subgroup and to identify useful clinical findings, we reviewed the charts of all children referred for growth evaluation over a 10-year period who were > or = -3 SD in height, > 2 years old, and prepubertal. Of 60 patients (36 males and 24 females), 22% had constitutional growth delay (CGD), 23% had growth hormone deficiency (GHD), 13% had Turner syndrome, and 22% had various forms of primary growth failure (mostly associated with intrauterine growth retardation). Eight percent had very slow growth over a prolonged period but no definable cause, and 12% did not fall into any of the above groups. For differentiating GHD from CGD, a subnormal height velocity for age during a 4- to 12-month observation period, a low insulin-like growth factor-1/somatomedin C (IGF-1/Sm-C), and low total or free T4, with normal TSH, were all highly predictive of a diagnosis of GHD.

Screening test for growth hormone deficiency: usefulness of L-dopa-propranolol provocative test

This is a retrospective review of 185 short children who were tested for growth hormone (GH) secretion using the L-dopa-propranolol provocative test. One hundred and thirty-three children were deemed to have passed the screening test when a GH concentration of greater than 15 miu/L was elicited after stimulation. Fifty-two failed the screening test, of which 33 were diagnosed as having growth hormone deficiency (GHD) when they had inadequate growth hormone response to insulin-induced hypoglycaemia. The other 19 were low-responders since they showed adequate GH response to insulin tolerance test (ITT). The low-responder rate to L-dopa-propranolol provocative test among short children who are not GH deficient was 12.5%. The low cost of L-dopa and propranolol, the simplicity and safety of the test, and the acceptable rate of low-responders make the test an effective screening test for GHD.

Constitutional delay of growth and adolescence

Constitutional delay of growth and adolescence (CDGA) is characterized by simultaneous retardation of growth, skeletal maturation and sexual development. Primarily longitudinal growth is impaired. The late occurrence of puberty is a secondary phenomenon brought about by the retarded physical development. Plasma levels of sex hormones and gonadotrophin correlate with bone age, not with chronological age. The provocation tests for growth hormone (GH) show normal results. In contrast, the spontaneous secretion of GH, measured half-hourly through the night or over 24 hours, is markedly reduced. Plasma somatomedin C is diminished. According to these data, CDGA is not a genuine GH deficiency but represents a cybernetic disorder coinciding with a false threshold for GH. As shown by large series of investigations, the final height of the patients lies on average 1.85 SD below the mean of healthy adults, with large individual variations. The decision as to whether treatment by growth promoting hormones should be performed should be made with regard to the individual height prognosis. With GH in physiological doses growth velocity can be considerably increased. Bigger doses of the hormone appear to be necessary in order to enhance final height. Treatment by anabolics and testosterone increases height velocity only, not adult height.