Combination growth hormone and estrogen increase bone mineralization in girls with Turner syndrome

Current understanding of hypothalamic amenorrhoea

Hypothalamic amenorrhoea (HA) accounts for approximately 30% of cases of secondary amenorrhoea in women of reproductive age. It is caused by deficient secretion of hypothalamic gonadotrophin-releasing hormone, which in turn leads to failure of pituitary gonadotrophin and gonadal steroid release. Functional HA (FHA) is defined as HA occurring in the absence of a structural lesion and is predominantly caused by significant weight loss, intense exercise or stress. Treatment of FHA is crucial in avoiding the long-term health consequences on fertility and bone health, in addition to reducing psychological morbidity. This article summarises our understanding of the mechanisms underlying FHA, the evidence base for its clinical management and emerging therapies.

Physiologic estrogen replacement increases bone density in adolescent girls with anorexia nervosa

Anorexia nervosa (AN) is prevalent in adolescents and is associated with decreased bone mineral accrual at a time critical for optimizing bone mass. Low BMD in AN is a consequence of nutritional and hormonal alterations, including hypogonadism and low estradiol levels. Effective therapeutic strategies to improve BMD in adolescents with AN have not been identified. Specifically, high estrogen doses given as an oral contraceptive do not improve BMD. The impact of physiologic estrogen doses that mimic puberty on BMD has not been examined. We enrolled 110 girls with AN and 40 normal-weight controls 12 to 18 years of age of similar maturity. Subjects were studied for 18 months. Mature girls with AN (bone age [BA] ≥15 years, n = 96) were randomized to 100 µg of 17β-estradiol (with cyclic progesterone) or placebo transdermally for 18 months. Immature girls with AN (BA < 15 years, n = 14) were randomized to incremental low-dose oral ethinyl-estradiol (3.75 µg daily from 0 to 6 months, 7.5 µg from 6 to 12 months, 11.25 µg from 12 to 18 months) to mimic pubertal estrogen increases or placebo for 18 months. All BMD measures assessed by dual-energy X-ray absorptiometry (DXA) were lower in girls with AN than in control girls. At baseline, girls with AN randomized to estrogen (AN E + ) did not differ from those randomized to placebo (AN E-) for age, maturity, height, BMI, amenorrhea duration, and BMD parameters. Spine and hip BMD Z-scores increased over time in the AN E+ compared with the AN E- group, even after controlling for baseline age and weight. It is concluded that physiologic estradiol replacement increases spine and hip BMD in girls with AN.

Endocrine control of body composition in infancy, childhood, and puberty

Body composition exhibits marked variations across the early human lifetime. The precise physiological mechanisms that drive such developmental adaptations are difficult to establish. This clinical challenge reflects an array of potentially confounding factors, such as marked intersubject differences in tissue compartments; the incremental nature of longitudinal intrasubject variations in body composition; technical limitations in quantitating the unobserved mass of mineral, fat, water, and muscle ad seriatim; and the multifold contributions of genetic, dietary, environmental, hormonal, nutritional, and behavioral signals to physical and sexual maturation. From an endocrine perspective (reviewed here), gonadal sex steroids and GH/IGF-I constitute prime determinants of evolving body composition. The present critical review examines hormonal regulation of body composition in infancy, childhood, and puberty.

Considerations for transition from paediatric to adult endocrinology: women with Turner's syndrome

Turner's syndrome (TS) is a genetic anomaly that results from complete or partial absence of one X chromosome and is the most commonly occurring chromosomal abnormality in females. While most females with TS present at birth or in early childhood, nearly one quarter present at adult services with primary or secondary amenorrhoea. It is only with the advent of clinics dedicated to adults with TS that we have realised the degree of occult pathology present in this group. Adults with TS are thought to have a reduced life expectancy, mainly due to excess cardiovascular risk, but they may also have multiple comorbidities including hypothyroidism, deafness, osteoporosis and the attendant problems of oestrogen deficiency and infertility. Many of these features may be affected by the timing of treatments in paediatrics - particularly the timing of growth hormone (GH) and oestrogen use. It is the role of adult TS services to audit the outcome of TS and to inform their paediatric colleagues of the long-term effects of childhood treatments. Thus, a multidisciplinary approach to focused adult care is needed, with consideration of how to optimise surveillance strategies in these women.

Importance of estrogen on bone health in Turner syndrome: a cross-sectional and longitudinal study using dual-energy X-ray absorptiometry

Osteoporosis and fractures are features in adults with Turner syndrome (TS). Using dual-energy x-ray absorptiometry, correcting bone mineral content (BMC) for height and lean mass (LTM) avoids misclassification of short children as osteopenic. Total body (TB), lumbar spine (LS), and femoral neck (FN) dual-energy x-ray absorptiometry scans were performed on 83 patients with TS (aged 4-24 yr). A prepubertal subgroup (n = 17) receiving GH was followed for 24 months. Age z-scores for height, TB BMC, LTM, the BMC/LTM ratio, and LS volumetric bone mineral density (vBMD) decreased significantly (P < 0.001) with age in prepubertal subjects (n = 51) but were constant in the combined pubertal and postmenarchal group (n = 32). Osteopenia was found in 14.5% (TB), 15.8% (LS), and 28.4% (FN) of patients. In the longitudinal subgroup, TB BMC z-scores decreased by -0.28 (0.31) in subjects remaining prepubertal (n = 11) but increased by 0.71 (0.56) in subjects entering puberty (n = 6; P = 0.007). The z-scores for height and LTM increased in both groups. Our results show a height-independent prepubertal decrease in bone mass accrual, which ceased with puberty. Optimizing bone mass in TS may require earlier induction of puberty than currently recommended. However, reduced FN volumetric bone mineral density and a dissociation of bone and muscle measures were age independent, suggesting an additional intrinsic bone defect.

The impact and management of Turner's syndrome in adult life

Turner's syndrome (TS), caused by an absent or structurally abnormal X chromosome, affects 1 in 2500 live female births. Most medical attention has focused on the attainment of final height in childhood and, when this has been achieved, many women are discharged to primary care. It has become increasingly evident that adults with Turner's syndrome are susceptible to a range of disorders such as osteoporosis, hypothyroidism and diabetes. Because of these, and because of the need for long-term oestrogen replacement, it seems most practical for adult health surveillance in TS to come under the remit of the endocrinologist. It must be accepted, however, that the reduced life expectancy in women with TS is largely accounted for by cardiovascular disease. Also, the commonly observed social isolation in adults with TS can be linked to deafness that is increasingly prevalent in an ageing group. Co-ordination of all these issues requires a dedicated multidisciplinary clinic along the lines of those in place in diabetes.

Gonadal dysgenesis and bone metabolism

Gonadal dysgenesis is defined as congenital hypogonadism related to abnormalities of the sex chromosomes. Because sex steroids play a central role in the acquisition and maintenance of bone mass, studies have been done to investigate bone status in patients with gonadal dysgenesis, particularly Turner's syndrome and Klinefelter's syndrome, which are the two most common types. The severe estrogen deficiency characteristic of Turner's syndrome (44, X0) is associated with a significant bone mass decrease ascribable to increased bone turnover, as shown by histological studies and assays of bone turnover markers. Estrogen therapy is followed by a significant bone mass gain and a return to normal of bone turnover markers, suggesting that it is the estrogen deficiency rather than the chromosomal abnormality that causes the bone mass deficiency, although abnormalities in the renal metabolism of vitamin D have been reported. Combined therapy with estrogens and growth hormone seems beneficial during the prepubertal period. In Klinefelter's syndrome (47XXY), serum testosterone levels are at the lower end of the normal range and dihydrotestosterone levels are low. Histological studies show depressed osteoblast function and a decrease in 5-alpha-reductase activity responsible for partial tissue resistance to androgens. Assays of bone turnover markers show evidence of increased bone turnover. The bone deficiency is most marked at the femoral neck and seems correlated with serum testosterone and estradiol levels. Androgen therapy has favorable effects on the bone only if it is started before puberty. Recent data suggest that estrogens may contribute to the development of demineralization in KS and that bisphosphonate therapy may be beneficial.

A multicentre trial of recombinant growth hormone and low dose oestrogen in Turner syndrome: near final height analysis

BACKGROUND

Turner syndrome accounts for 15-20% of childhood usage of growth hormone (GH) in the UK but final height benefit remains uncertain. The most effective strategy for oestrogen replacement is also unclear.

METHODS

Fifty eight girls who, at start of treatment, were of mean age 9.1 years and projected final height 142.2 cm were randomised to receive in year 1, either low dose ethinyloestradiol 50-75 ng/kg/day, GH 28 IU/m(2) surface area/week as a daily injection, or a combination of ethinyloestradiol and GH. After the first year, the ethinyloestradiol treated girls received combination treatment. After two years, girls aged over 12 years were given escalating ethinyloestradiol to promote pubertal development.

RESULTS

Near final height was available for 49 girls at age 16.5 years, 146.8 cm, representing a gain of 4.6 cm, range -7.9 to +11.7 cm. Twelve of the 49 girls gaining 7.5 cm or more were less than 13 years at the start and had received GH for at least four years. Height gain was correlated with greater initial height deficit. Fifteen girls (31%) reached 150 cm or more compared to a predicted 10%. Early supplementation with ethinyloestradiol provided no final height advantage.

CONCLUSIONS

Final height gain was modest at 4.6 cm. Younger, shorter girls gained greatest height advantage from GH. Low dosage ethinyloestradiol before planned induction of puberty was not beneficial.

Health of teenagers in residential care: comparison of data held by care staff with data in community child health records

AIM

To identify whether there are gaps in information available to care staff about the health related needs of one group of teenagers in residential care which could be addressed by reviewing the community child health records.

METHODS

Data were collected on the residents of a children's home during a three month period, comparing information from children's home records with information from community child health records.

RESULTS

Data were collected from children's home records for 36 residents and child health records obtained for 29. Child health records provided the only information on 53% of child protection registrations and 17.5% of statements of special educational needs. Most information on birth history, developmental and early medical history, immunisations, growth, hearing, and colour vision came from the child health records. Immunisation uptake was below the national average, and particularly poor for BCG and school leaver tetanus, low dose diphtheria, and polio boosters. Emotional and behavioural problems were present in 100% of the residents and this information was known to the home. Poor use of "Looking After Children" records was identified, and there was a paucity of information in the home records and child health records about results of annual looked after medical examinations.

CONCLUSION

Important information about the health needs of looked after teenagers was not known to the children's home staff. Community paediatricians should be proactive in identifying and addressing these needs.

Spontaneous, but not induced, puberty permits adequate bone mass acquisition in adolescent Turner syndrome patients

Lumbar L2-L4 bone mineral density (BMD) values were measured in 37 adolescent and young adult Turner syndrome patients. Nine had developed spontaneous puberty and had had regular menses since menarche (12.55 years +/- 1.17 years) to the time of BMD evaluation (14.96 years +/- 1.26 years). In the other 28, puberty was induced with increasing doses of oral ethinyl estradiol (2.5-10.0 microg/day, for 2 years) and later administration of estrogen/gestagen therapy up to the time of BMD evaluation. In 18, the adolescent group, menarche appeared at 14.68 years +/- 0.63 years and BMD was evaluated at 17.77 years +/- 0.70 years, and in the other 10, the young adult group, menarche appeared at 14.47 years +/- 0.53 years and BMD was evaluated at 20.90 years +/- 0.68 year. BMD values were in the normal range in those who had developed spontaneous puberty (Z score values, -0.24 +/- 0.22) and in the osteopenia range in those in whom puberty was induced (Z score values, -2.09 +/- 0.79 and -2.18 +/- 0.32 for the adolescent and young adult groups, respectively) p < 0.0001. Height Z score values were similar in all three groups (-3.45 +/- 0.77, -3.15 +/- 0.83, and -3.08 +/- 0.33, respectively). No significant differences in calcium intake or physical activity were found among groups. Neither the karyotype distribution nor growth hormone (GH) therapy (five in the spontaneous puberty and six in the induced puberty groups had been treated for a 3.5- to 4.4-year period) explained the differences in BMD values. Because the main difference between groups was the availability of estrogens to bone tissue from infancy to menarche and of estrogens/gestagens from then on up to the time of BMD evaluation, our results suggest that normal gonadal function from infancy to adulthood may be required for adequate bone mass peaking. Early detection of osteopenia and improvement in general measures for adequate bone mass peaking (calcium intake and physical activity) should be considered mandatory in the health care of these patients.