What is the rationale for growth hormone therapy in Turner's syndrome?

The Rationale for Growth Hormone Therapy in Children with Short Stature

Growth hormone (GH) was first isolated from cadaver pituitary glands, requiring laborious and expensive collection of glands, followed by extraction and purification of the hormone. This limited supply restricted its use to children with severe GH deficiency who were treated with low dosages and suboptimal schedules. The development of recombinant DNA-derived GH, allowed the production of virtually unlimited amounts of GH, leading to the approval for therapy for a large number of childhood conditions characterized by non-GH deficient short stature. The aim of this review is to provide a critical overview on the daily use of GH in two paradigmatic conditions of non-GH deficient short stature which are children born small for gestational age and with idiopathic short stature, highlighting the available strength of evidence for efficacy and safety.

Symptomatic versus substitution growth hormone therapy in short children: from auxology towards a comprehensive multidimensional assessment of short stature and related interventions

There is an ongoing debate as to whether symptomatic growth hormone treatment (GHT) in short children without growth hormone deficiency (GHD) is justified, since there is no substitutional indication. The increasing evidence that final height cannot be normalized in these patients (e.g. in Ullrich-Turner syndrome) reinforces this controversy. We have focused on the empirical evidence on the psychosocial and physical meaning of being short in childhood as well as on the underlying assumptions of the different GHT indications. The indication for GHT in patients with non-GHD may be seen as a pharmacotherapeutic intervention in order to prevent the developmental, physical and psychosocial risks associated with short stature. This requires a qualitative shift in methodological assessment with respect to the psychosocial and physical impact of being short as well as of the potential benefit of new treatment indications in terms of a more comprehensive evaluation including health-related quality of life for these patients.

Celiac disease and Turner syndrome

BACKGROUND

Short stature is one of the features of Turner syndrome and a form of presentation of monosymptomatic celiac disease.

METHODS

The recognition of celiac disease in two antiendomysium antibody-positive Turner syndrome girls who did not respond to growth hormone treatment led us to perform as a screening for celiac disease IgA and IgG antigliadin antibodies and antiendomysium antibodies determination in other 35 Turner syndrome patients. Intestinal biopsy was proposed to the antiendomysium antibodies-positive girls; in the former, subtotal villous atrophy was found; in the latter, one parent's consent for intestinal biopsy was not obtained.

RESULTS

The prevalence of celiac disease in Turner syndrome patients observed in the present study (8.1 if we consider 3 villous atrophy, 10.8 if we consider 4 antiendomysium antibody-positive) is quite high and seems to indicate that the association of these two disorders could not be coincidental. As to the clinical picture, celiac disease appeared atypical in one case, typical in another one and as a silent form in the third case. Of the 3 cases with villous atrophy on gluten-free diet growth hormone therapy was not effective in two girls, who were older than 16 years, while in the younger patient, detected by the screening, a significant increment of height velocity and height Standard Deviation Score for Chronological Age according to Turner references was observed.

CONCLUSIONS

This study suggests that celiac disease can be associated with Turner syndrome and even responsible for a failure of growth hormone therapy. Therefore we propose to perform in Turner syndrome patients antiendomysium antibody determination as a screening followed by intestinal biopsy in positive cases. This would be advisable at least before starting growth hormone treatment.

Psychological aspects of Turner syndrome

Turner syndrome (TS) is a sex-chromosome disorder, occurring in 1 in 2500 female births. The principal features of TS are short stature and dysfunctional gonads, resulting in a lack of sex hormones, incomplete pubertal development and impaired fertility. The aim of this paper is to review the literature on the psychological effects of TS. The main areas covered relate to well-being and psychopathology, self-esteem, social functioning, gender identity, partner relations and sexual functioning, coping, family aspects and clinical aspects of cognitive impairment. Research on the psychological effects of medical intervention is described, and the methods used for psychological and educational support are presented. Finally, methodological issues are discussed and areas for future research are proposed.

Does growth-hormone supplementation affect adult height in Turner's syndrome?

BACKGROUND

By comparison with historical controls, the effect of treatment with growth hormone on adult height in Turner's syndrome was initially reported as uniformly and strongly positive. Because randomised controlled trials are not near completion, we report our experiences in an open study.

METHODS

We examined adult height, projected and attained, in 31 patients (17 treated with subcutaneous recombinant human growth hormone, up to 15 mg a week, outside of a controlled trial and 14 untreated contemporaries).

FINDINGS

Contingency table analysis of attained versus projected height showed significantly higher values in treated patients although only 4 of 17 had final heights of 5 cm or more over projection. Patients' and treatment variables (height, bone-age delay, oestrogen replacement) that interfere with adult height projection confounded the analysis of adult height data.

INTERPRETATION

Girls with Turner's syndrome should be counselled cautiously about the expectation of a strongly positive effect of treatment on adult height. Completion of the randomised controlled trials to adult height is needed to establish the effect of growth-hormone supplementation on adult height in Turner's syndrome and the psychological effect of treatment.

New peptide and protein drugs

A view is presented on a number of recent developments, the present state and the perspectives, especially from a pharmacotherapeutic viewpoint, for peptide and protein drugs. The expanding use and the increasing experience create new pharmacotherapeutic modalities. Peptide and protein drugs comprise among others proteins isolated from human sources, and peptides and proteins made by biotechnology including monoclonal antibodies, recombinant human hormones, cytokines and growth factors. In the field of vaccine development also innovation is taking place. Optimal application schemes of these drugs may not have been reached and (clinical) pharmacists should contribute to the optimization. Since recombinant technology has abolished scarcity for a number of these drugs--especially 'physiological' substances--special ethical problems regarding an unlimited application or expansion of the indications may arise.

Is obesity-related insulin status the cause of blunted growth hormone secretion in Turner's syndrome?

Growth hormone (GH) secretion is reduced in girls with Turner's syndrome (TS) at pubertal age. We have recently proposed that the impairment of GH release in TS girls might be secondary to obesity. In the present study, we assessed the influence of overweight-related insulin status on spontaneous GH secretion in a group of 15 TS girls. Eighteen age-matched short normal subjects and six short obese prepubertal children were chosen as controls. Anthropometry, spontaneous GH secretion, insulin-like growth factor-I (IGF-I) serum levels, basal fasting insulin, and glucose concentrations were determined. The percentage of ideal body weight (IBW) was used as an index of nutritional status. Baseline fasting glucose (milligrams per deciliter) to insulin (milliunits per liter) ratio (G/I) was chosen as an index of insulin resistance. GH secretion was significantly lower in TS girls than in non-obese children (P < .005), whereas no significant difference was seen between TS and obese subjects. IGF-I levels were not statistically different in all groups. GH secretion was confirmed to be related to the degree of overweight (r = -.52, P < .05 in TS girls and r = -.74, P < .0001 in control group). G/I was closely related to both the percentage of IBW (r = -.59, P = .02) and GH level (r = .57, P = .03) in TS patients. These results confirm that the blunted GH secretion in TS patients is dependent on nutritional status, and suggest that insulin resistance secondary to overweight might represent the pathophysiologic link between the obesity-related metabolic status and impaired GH secretion.