Growth hormone therapy in Turner syndrome

Short stature is the single most common physical abnormality in Turner syndrome (TS) with adult stature averaging 20 cm shorter than that of the general population. Randomized, placebo-controlled studies to final adult height have proven that GH therapy is effective in increasing stature in TS. Recently, randomized, controlled studies have demonstrated that adjunctive therapies with low-dose estrogen or low-dose oxandrolone enhance stature further. These therapies may provide benefits beyond height augmentation.     

Short stature in Noonan syndrome: response to growth hormone therapy.

BACKGROUND: Growth hormone (GH) has been used to promote growth in both the short and long term in a number of dysmorphic syndromes, including Turner syndrome. As this condition shares many clinical features with Noonan syndrome, it would seem logical to treat the latter group with GH. AIMS: To assess the short and long term response to GH therapy in patients with Noonan syndrome. METHODS: Analysis of patients with Noonan syndrome in the Pharmacia & Upjohn International Growth Study (this post-marketing database contains data on the majority of patients currently treated with GH in the UK). A questionnaire was also sent to participating clinicians. RESULTS: Data on 66 patients (54 males) were available for study. At the start of GH therapy children were short, compared with both normal and Noonan children. During the first year of GH therapy height velocity increased from a mean of 4.9 to 7.2 cm per year. For patients treated long term with GH, mean height SDS increased from -2.9 pretreatment to -2.6 after one year and -2.3 after five years. Of the 10 patients at near final height, only one had a height above the 3rd centile for normal adults and above the mean for untreated Noonan patients. The mean increment in final height was 3.1 cm (range -1.1 to 6.5 cm). CONCLUSIONS: GH therapy in patients with Noonan syndrome will improve height velocity in the short term. Longer-term therapy results in a waning of effect; initial indications are that final height is not improved substantially in most patients.     

Growth hormone treatment of Turner syndrome patients with insufficient growth hormone response to pharmacological stimulation tests

Growth before and during treatment with biosynthetic human growth hormone (hGH) was studied in 13 patients with Turner syndrome (TS) and a growth hormone (GH) response of less than 10 g/l to two standard provocative tests. During 1 year of treatment with hGH (0.15 IU/kg per day) height velocity (mean±SD) increased significantly (P<0.001) from 3.7±1.8 cm/year to 7.6±1.5 cm/year. The auxological data in these girls before and during treatment with hGH were similar to those observed in TS patients with a normal response of GH to pharmacological stimuli. It is concluded that in girls with Turner syndrome GH testing should only be performed when height velocity is below the Turner norm. In TS patients with residual growth potential a clinically significant growth acceleration can be obtained with a higher-than-replacement dose of hGH, i.e. 0.15 IU/kg per day, regardless of GH testing.     

Growth hormone treatment in Noonan syndrome

Growth responses to growth hormone (GH) treatment in Noonan syndrome are compared with those in short children with the other growth disorders. The responses in Noonan syndrome are much less than those in children with GH deficiency, a little less than those in children with non-endocrine short stature and almost the same as those in children with Turner syndrome. As it is speculated that GH induces puberty earlier that expected in Noonan Syndrome, the efficiency of GH treatment for final height in Noonan syndrome is not promising.     

Combined therapy with growth hormone and oxandrolone in adolescent girls with Turner syndrome

Five adolescent girls with Turner syndrome (mean age 13.9 years, mean bone age 12.0 years) were treated with both recombinant human growth hormone (rhGH) and oxandrolone for 2 years with an average increment in height of 13.4 cm. The mean bone age advanced by only 1.2 years, providing an increase in the mean estimated mature height of 9.2 cm. We conclude that rhGH and oxandrolone benefit older teenagers with Turner syndrome because of an increased growth rate with slow progression of skeletal maturation.     

Growth hormone testing in short children and their response to growth hormone therapy

Because current concepts of growth hormone (GH) testing and GH treatment have become controversial, we investigated the GH secretory patterns in children with normal and short stature. Twenty-four-hour serum GH levels were evaluated in three groups of children. Group 1 was composed of children with normal height (mean height = 0.02 SD, n = 33); group 2 was composed of short children (less than 5th percentile, n = 63) with normal results on provocative GH testing; and group 3 was composed of short children (less than 5th percentile, n = 7) with subnormal results on provocative GH testing. Mean +/- SD (range) GH levels during 24-hour studies of GH secretion were 1.6 +/- 1.1 (0.5 to 5.6), 1.8 +/- 1.2 (0.6 to 6.3), and 0.9 +/- 0.4 (0.5 to 1.7) ng/ml in groups 1, 2, and 3, respectively. No statistical difference existed in mean GH levels between groups 1 and 2 or between groups 1 and 3. The mean GH concentration from 24-hour studies in group 2 children did not correlate with chronologic age, height standard deviation, growth rates, or insulin-like growth factor 1 levels. The linear growth rate of 26 of 28 children in group 2 who received GH therapy for 6 months improved by 2 cm/yr or more; the mean +/- SD growth rate was 4.0 +/- 1.3 and 8.8 +/- 2.0 cm/yr during control and treatment periods, respectively, for these 28 children. Mean GH levels from testing did not predict response to GH during 6 months of therapy. Children with slower growth rates responded better to GH therapy (p less than 0.05). We conclude that (1) in 24-hour studies, GH levels in normal children overlapped with those of short children, including those with classic GH deficiency, (2) in 24-hour studies, GH levels did not predict responses of linear growth to short-term GH treatment, nor did they correlate with children's heights or growth velocities, and (3) the majority of short children in group 2 treated with GH for 6 months had an increase in linear growth velocity, the mean +/- SD change being 4.8 +/- 2.0 cm/yr.     

Growth hormone treatment in Turner syndrome accelerates growth and skeletal maturation

Sixteen girls with Turner syndrome (TS) were treated for 4 years with biosynthetic growth hormone (GH). The dosage was 4IU/m² body surface s.c. per day over the first 3 years. In the 4th year the dosage was increased to 61 U/m² per day in the 6 girls with a poor height increment and in 1 girl oxandrolone was added. Ethinyl oestradiol was added after the age of 13. Mean (SD) growth velocities were 3.4 (0.9), 7.2 (1.7), 5.3 (1.3), 4.3 (2.0) and 3.6 (1.5) cm/year before and in the 1st, 2nd, 3rd and 4th year of treatment. Skeletal maturation advanced faster than usual in Turner patients especially in the youger children. Although the mean height prediction increased by 5.6 cm and 11 of the 16 girls have now exceeded their predicted height, the height of the 4 girls who stopped GH treatment exceeded the predicted adult height by only 0 to 3.4 cm.     

Growth-stimulating effects of human growth hormone therapy in patients with Turner syndrome

We determined the effect of pituitary human growth hormone treatment on the growth rate of 52 children with Turner syndrome. The pretreatment growth rate was 3.2 +/- 0.8 cm/yr. Growth hormone treatment (0.2 IU/kg three times per week) resulted in enhancement of the growth rate to 5.9 +/- 1.4 cm/yr for the first year of therapy. The bone age advanced approximately 1 year during the year of therapy. The growth hormone therapy was discontinued at 12 months, and the mean growth rate decreased to pretreatment levels, 3.1 +/- 1.9 cm/yr; 26 of 41 patients actually had post-treatment growth rates that were less than the pretreatment rate. Glucose tolerance tests at 6-month intervals did not indicate an effect of hGH treatment on glucose intolerance. Several patients had glucose intolerance that preceded hGH treatment, but this remained stable during treatment; glucose intolerance likely was related to obesity in this group of patients. Basal and hGH-stimulated somatomedin C levels (32 patients) correlated with age of the patient but not with growth rate during therapy. We conclude that hGH therapy can accelerate the growth rate of patients with Turner syndrome. The growth rate increased to "normal" levels and was dependent on continued treatment with hGH. If the response continues, long-term treatment of Turner syndrome may result in increased adult height.     

Growth hormone deficiency in a child with Williams-Beuren syndrome. The response to growth hormone therapy

Pre- and postnatal growth retardation of unknown pathogenesis is a common clinical feature in patients with Williams-Beuren syndrome (WBS). However, growth hormone deficiency (GHD) has not been considered a major cause of growth retardation. There is only one patient in the literature with confirmed GHD who responded well to human growth hormone (hGH) therapy. We report a female infant with confirmed WBS who, through provocative testing, was found to have GHD and who responded satisfactorily to hGH therapy. Height SDS was -4.2 at the age of 12 months when hGH was initiated and increased to -0.8 at the age of 4.25 years. The pathogenesis of GHD in our patient is unclear. Nevertheless, the elevated levels of prolactin and the response of hGH to growth hormone releasing hormone (GHRH) administration are indicative of a hypothalamic rather than pituitary defect. In conclusion, GH deficiency might contribute to the growth failure in a number of patients with WBS and in such cases hGH therapy will most likely improve final height.     

Growth hormone treatment regimens in girls with Turner syndrome

To optimize growth hormone (GH) treatment in girls with Turner syndrome, two multicentre studies were carried out in The Netherlands: a frequency-response study (study 2) and a dose-response study (study 2). In study 1, 19 girls with Turner syndrome, aged 11 years or older, were treated with one or two daily injections of GH at a total dose of IU/m²/day (0.067 mg/kg/day) and ethinyloestradiol given orally at a dose of 0.05 μg/kg/day. All the girls reached final height. The mean (±SD) gain in final height was not significantly different between the once- or twice-daily regimens (7.6 ± 2.3 versus 5.1 ± 3.2 cm, respectively). The mean final height attained was 155.5 ± 5.4 cm. All the girls exceeded their adult height prediction. In study 2, 68 girls with Turner syndrome, aged 2-11 years, were randomized into three dosage groups: A, B and C. During the first year, the girls in all the groups received GH at a dose of 4 IU/m²/day (0.045 mg/kg/day), which group A continued to receive throughout the study. At the start of the second year groups B and C were switched to a dose of 6 IU/m²/day, which the girls in group B continued to receive for the reminder of the study. At the start of the third year, the girls in group C were switched to a dose of 8 IU/m²/day (0.090 mg/kg/day) for the remainder of the study. After 7 years of GH treatment, height SDS (based on Turner syndrome and normal population references) increased significantly in all three groups, but significantly more in groups B and C compared with group A ( p = 0.02 and p =0.001, respectively). Predicted adult height increased significantly, without a significant difference between the three groups. The mean final heights of 25 of the girls were 159.1, 161.8 and 162.7 cm for groups A, B and C, respectively.     

Growth increments with low dose intermittent growth hormone and fluoxymesterone in first year of therapy in hypopituitarism.

The availability of a commercial preparation of human growth hormone (hGH) prompted a study in children with hypopituitarism to determine the efficacy of a lower dose of hGH. Thirteen children, ages 4 years 3 months to 13 years 7 months, were given hGH concomitant with fluoxymesterone in an intermittent regimen. The hGH was given intramuscularly, 1 IU daily for 12 to 36 days in each course. There were four courses per year. The fluoxymesterone was given orally, 1 to 2 mg. The total amount of hGH administered was between 48 and 112 IU per year, as compared with the regimen of 312 IU per year, 2 units three times a week. The growth velocity in all 13 children improved, and the mean growth velocity was 6.4 cm +/- 1.13 SD. The mean bone age increment was 0.57 years +/- 0.14 SEM in one chronological year of therapy. The low dose regimen permits a significant reduction in cost of hGH without causing undue advance in bone age.     

Growth hormone secretory dynamics in Turner syndrome

We investigated whether a decrease in serum growth hormone contributes to the short stature of adults with Turner syndrome by measuring the 24-hour profile of serum growth hormone in 30 patients aged 2 to 20 years. Growth hormone pulses were defined as a rise from nadir to peak that exceeded three times the intraassay coefficient of variation. Girls with Turner syndrome aged 2 to 8 years did not have statistically different growth hormone levels, peak amplitudes, and peak frequencies compared with those in age-matched controls. By contrast, girls with Turner syndrome aged 9 to 20 years had significantly decreased mean 24-hour growth hormone levels, peak amplitudes, and peak frequencies compared with those in age-matched normal girls. Patients with Turner syndrome of all ages had decreased serum somatomedin-C concentrations and delayed bone ages. We conclude that a relative deficiency of growth hormone in pubertal patients with Turner syndrome may contribute to their adult short stature.