Dose-response relationship in the treatment of hypopituitary children with human growth hormone: a retrospective survey

[Does the growth hormone pharmacokinetic profile help to predict the treatment response?]

Pharmacokinetics of subcutaneously administered recombinant growth hormone (rGH) were studied in nine GH deficient children at the time of the first rGH injection at the beginning of treatment. Serum GH levels were determined by four different methods: immunofunctional assay, immunofluorometric assay and two bioassays on Nb2 cells. The results showed similar profiles whatever the type of assay with a concentration peak reached 2 to 6 hours after subcutaneous injection; however, large individual variations in peak amplitude were observed. They were related to individual variations in the growth velocity during the first year of rGH treatment. These variations are possibly related to individual differences in rGH degradation at the site of injection. Study of rGH absorption profiles appears useful in the evaluation of rGH treatment in GH deficient patients.

The level of bioavailable growth hormone (GH) after the first GH injection predicts the first year's growth response in GH-deficient children

Serum GH levels were measured in 9 prepubertal children with growth hormone (GH) deficiency using an immunofluorometric assay (IFMA) and a Nb2 cell bioassay, prior to and 2, 4, 6 and 12 hours after the first hGH subcutaneous injection (sc) (0.1 IU/Kg). After this first acute phase, hGH treatment was continued regularly at a dose of 0.1 IU/kg per day at bedtime. The acute pharmacokinetic profile was similar in the patients irrespectively of the assay used: serum GH usually starts to rise after 2 hours, peaks by 4 or 6 hours and drops back to near baseline levels 12 hours after s.c. GH administration. A great variation in the amplitude of peak levels was observed among the patients. The assays significantly (p<0.0001) correlate with each other in all subjects. An increase in serum GH values as evaluated by the Nb2 bioassay was observed in most children after s.c. GH injection, suggesting that the administered hormone preserves its biological activity. The individual variations in GH bioactivity in our GH-deficient children could be due to different mechanisms of the drug's degradation at the site of injection or in circulation. Pre-treatment height velocity calculated as standard deviation scores (SDS) significantly increased (p<0.001) from -2.77+/-0.42 to 1.22+/-0.87 SDS after a 12-month period of GH treatment in 8 patients who had already completed the first year of therapy, although it varied considerably among subjects. A higher serum GH peak value evaluated by both assays corresponded to a higher growth response during the 1st year, but not in the 2nd year of GH therapy. In conclusion, the degree of GH bioactivity released into circulation after sc GH injection may vary considerably among GHD patients and correlates with the growth response observed during the 1st year of GH therapy.

Combination treatment with growth hormone and gonadotropin-releasing hormone analogs in short normal girls

To improve final adult height, we treated with growth hormone (0.65 +/- 0.07 (mean +/- SD) IU.kg-1.wk-1) and gonadotropin-releasing hormone analogs (66 +/- 9 micrograms.kg-1 every 28 days) a group of seven short normal girls in early puberty with a chronologic age (CA) of 11.50 +/- 0.95 years, predicted adult height (PAH) lower (0.003 < p < 0.001) than mean target height, and without any endocrine abnormalities. The results were compared with those obtained in a similar group of seven untreated girls considered as control subjects. The mean period of combined therapy was 2.01 +/- 0.52 years; in two subjects treatment is still in progress. The value of height standard deviation score for bone age (BA) improved from -1.69 +/- 0.47 to -1.04 +/- 0.56 (p = 0.001); height age (HA)/BA ratio also increased from 0.83 +/- 0.05 to 0.90 +/- 0.04 (p < 0.01), as did PAH (from 146.8 +/- 4.4 to 152.9 +/- 3.6 cm; p < 0.002). The ratio of gain in HA to gain in BA was 2.08 +/- 0.78. Pubertal stages showed an arrest in five cases and a regression in the other two girls. After administration of gonadotropin-releasing hormone analogs was interrupted, in four of five girls growth hormone was administered alone for a further period of 6 to 18 months to improve their physiologic growth spurt. The present height in five girls is higher than PAH before therapy. In the treated girls the height values for BA, for BA/CA and HA/BA ratios, and for PAH were higher (0.002 < p < 0.04) than those in control subjects. This preliminary study demonstrates that combination therapy with growth hormone and gonadotropin-releasing hormone analogs in short, endocrinologically normal girls may be useful in improving both height prognosis and predicted adult height. Further studies are necessary to reach definitive conclusions regarding the efficacy of this kind of therapy.

Growth hormone deficiency throughout puberty

Growth during puberty does not appear to be the major determinate of final height in isolated GH deficient patients. Early diagnosis and commencement of therapy are probably the most important factors, as reflected by the correlation between final height and height at the onset of puberty. The cost effectiveness of increasing the dose of GH during puberty does not appear to represent any advantage from the data presently available. Indeed, such an approach may have a deleterious effect on final height by shortening the duration of pubertal maturation. Further prospective studies are required to demonstrate the effectiveness of manipulating the onset and duration of puberty using gonadotrophin releasing hormone analogues on final height in isolated GH deficiency.

Height prognosis of children with true precocious puberty and growth hormone deficiency: effect of combination therapy with gonadotropin releasing hormone agonist and growth hormone

We evaluated height prognosis and therapeutic efficacy of long-term, combination therapy with gonadotropin releasing-hormone agonist and growth hormone (GH) in five children (three girls) with coexistent precocious puberty and GH deficiency. Their clinical characteristics and growth response were compared with those of 12 girls with idiopathic true precocious puberty and eight prepubertal GH-deficient children (one girl). Precocious GH-deficient subjects were older than the precocious GH-sufficient children (9.5 +/- 1.8 years vs 6.5 +/- 1.3 years; mean +/- SD), but bone ages were comparable (12 +/- 3.7 years vs 10 +/- 0.9 years); their chronologic age was similar to that of the prepubertal GH-deficient children (9.6 +/- 2.1 years), but bone age was significantly more advanced (6.9 +/- 2.3 years). The mean height velocity of the prepubertal GH-deficient children (3.8 +/- 1.5 cm/yr) was lower than that of the precocious GH-deficient subjects (6.7 +/- 1.6 cm/yr) and the precocious GH-sufficient children (9.5 +/- 2.9 cm/yr). Baseline adult height prediction z scores were significantly lower in the precocious GH-deficient children (-3.7 +/- 1.0) than in either the precocious GH-sufficient children (-2.2 +/- 1.0) or the prepubertal GH-deficient subjects (-1.5 +/- 0.8). During therapy with gonadotropin releasing-hormone agonist, growth rates slowed to an average of 3.7 cm/yr in the precocious GH-deficient children but increased after the addition of GH to 7.4 cm during the first year of combination therapy. After 2 to 3 years of combination therapy, height predictions increased an average of 10 cm, compared with an increase of 2.8 cm in the precocious GH-sufficient group treated with gonadotropin releasing-hormone agonist alone. We conclude that combination treatment with gonadotropin releasing-hormone agonist and GH improves the height prognosis of children with coexistent true precocious puberty and GH deficiency, but falls short of achieving normal adult height potential.

Puberty in children with idiopathic growth hormone deficiency on growth hormone treatment: preliminary analysis of the data from the Kabi Pharmacia International Growth Study

In total, 524 children (335 boys, 189 girls) with idiopathic growth hormone deficiency (GHD) who had entered puberty after at least 1 year of growth hormone (GH) treatment were studied. Spontaneous onset of puberty occurred in 319 boys and 174 girls, and puberty was induced in 16 boys and 15 girls. Median chronological and bone ages at onset of spontaneous puberty were 14.8 and 13.4 years in boys, and 13.3 and 11.8 years in girls, respectively. Age at onset of spontaneous puberty was correlated to age at start of GH treatment. Puberty was induced at a median chronological age of 16.0 years in boys and 14.4 years in girls. Height velocity increased in the year before spontaneous puberty in boys and girls, and rose further to a maximum (median, 8.3 cm/year) in the first year of puberty in boys. In girls, the maximum height velocity occurred in the year before puberty (median, 6.5 cm/year). Height velocity increased in the year before spontaneous puberty in boys and girls, and rose further to a maximum (median, 8.3 cm/year) in the first year of puberty in boys. In girls, the maximum height velocity occurred in the year before puberty (median, 6.5 cm/year). Height velocity during the first year of puberty was inversely correlated to age at puberty onset (r = -0.56, p = 0.0001). After medical induction of puberty, height velocities in the first year of puberty were 5.4 and 3.4 cm/year for boys and girls, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Near normalization of adolescent height with growth hormone therapy in very short children without growth hormone deficiency

Ten prepubertal children with stature at or below the 1st percentile for height and without growth hormone deficiency received 0.3 U recombinant growth hormone per kilogram daily for 2 years before puberty. Their growth velocity increased from 4 +/- 0.3 cm/yr before treatment to 10.7 +/- 0.6 and 8.8 +/- 0.6 cm, respectively, during the first and second years of treatment, and then remained at 5.7 +/- 0.7 cm the year after the end of growth hormone administration. This resulted in a near normalization of adolescent height. Bone maturation paralleled chronologic age, and therefore the expected final height of the children increased by approximately 10 cm. Administration of growth hormone induced a reversible hyperinsulinemia, with moderate and transient changes in glucose metabolism. A prospective, randomized study, including an untreated cohort, will be needed to confirm the effects on final height and to determine the magnitude of the response in familial short stature.

Growth of males with idiopathic hypopituitarism without growth hormone treatment

We report auxologic data on 23 males with idiopathic hypopituitarism who grew up at a time when human growth hormone (GH) was not yet available, while receiving other appropriate hormonal substitution. We had reported previously that their adult heights were not significantly less than those of similar patients who had received GH. In the absence of GH the pubertal growth period was remarkably protracted, averaging 8.7 years for 19 patients during androgen substitution. Pubertal increment in height averaged 20.4 cm during induced puberty, a figure which compares favourably with those reported for GH-treated patients. This implies that GH does not increase the height gained during pubertal growth; the increase in the rate of growth appears to be off-set by a rise in the rate of skeletal maturation. During pubertal growth acceleration of growth of the skeleton seems unavoidably associated with acceleration of its maturation. Adult heights were significantly correlated with the heights at the time of onset of pubertal growth. This is evidence in favour of attempts to stimulate prepubertal growth much more than hitherto by earlier, higher, and more frequent doses of GH. It remains to be proved, however, that before puberty the processes of growth and maturation of the skeleton can be dissociated.