Growth hormone deficiency, brain development, and intelligence.

Twenty-nine patients with growth hormone (GH) deficiency were selected according to the following criteria: no evidence of reversible GH deficiency, onset of growth retardation in early childhood, and no evidence of pituitary tumors or other direct pituitary trauma. Fourteen patients had evidence of multiple hormone deficiencies, 14 had isolated GH deficiency, and one patient questionable isolated GH deficiency. Psychometric testing showed a normal IQ distribution. The GH deficiency was not associated with deficiencies in specific mental abilities. Likewise, GH treatment in later childhood and adolescence did not seem to influence intelligence. Patients with multiple hormone deficiencies had somewhat lower IQs than patients with isolated GH deficiency when socioeconomic status was controlled. We conclude that GH deficiency itself does not seem to affect human brain development and intelligence.     

Diagnostic limitations of spontaneous growth hormone measurements in normally growing prepubertal children

To evaluate whether the measurement of the spontaneous overnight growth hormone secretion in prepubertal children clearly separated normal children from subjects with growth hormone deficiency, we studied 45 prepubertal normally growing children (10 with normal height and 35 with constitutional growth delay) and compared their overnight growth hormone secretion with that of a group of subjects with either isolated growth hormone deficiency or neurosecretory dysfunction. Peak growth hormone levels (greater than or equal to 10 ng/mL) following oral clonidine administration were normal in individuals with normal height, constitutional growth delay, and neurosecretory dysfunction, as was the basal somatomedin C concentration; subjects with growth hormone deficiency had low peak growth hormone levels (less than 10 ng/mL) following oral clonidine administration as well as low basal somatomedin C values. The mean 9-hour overnight growth hormone concentration, total growth hormone output, total number of nocturnal pulses, and the mean peak growth hormone response during nocturnal sampling were similar in the normal height and constitutional growth delay groups and significantly greater than those seen in subjects with either growth hormone deficiency or neurosecretory dysfunction. Twelve (26.6%) of 45 normally growing children (4 to 10 normal height and 8 of 35 constitutional growth delay), however, had low overnight growth hormone levels (less than 3 ng/mL), which overlapped results obtained in the growth hormone-deficient or neurosecretory dysfunction groups. Frequent overnight growth hormone (GH) sampling does not always separate normal-growing children from those with partial or complete GH deficiency. In our this study over one quarter of the normally growing children had overnight GH levels in the range of children with either GH deficiency or neurosecretory dysfunction. These findings, in addition to the cost and difficulty in performing this test, do not support the measurement of spontaneous GH as a routine test in short but normally growing prepubertal children.     

Genetic studies in idiopathic short stature

Idiopathic short stature (ISS) refers to a heterogeneous group of children with marked growth failure of unknown cause, and encompasses familial short stature and constitutional delay of growth. It has been postulated that specific genetic mutations may explain certain cases of growth failure. Some patients with growth hormone (GH) deficiency have mutations in the GH-releasing hormone receptor or GH gene, whereas patients with GH insensitivity syndrome have mutations in the GH receptor or insulin-like growth factor-I gene. It appears that heterozygous mutations of the GH receptor may cause partial GH insensitivity in a subset of patients with ISS. Defects in the short stature homeobox-containing gene (SHOX) in the pseudoautosomal region of the sex chromosomes may cause the growth failure seen in the Leri-Weill and Turner syndromes, and in some familial cases of ISS. Further research into stature-related genes will likely contribute to our understanding of this population.     

Growth hormone and developmental ocular function: clinical and basic studies

While growth hormone (GH) is obligatory for postnatal growth, its possible involvement in ocular development and vision is poorly understood. The eye is, however, a target site for GH action and GH production and GH may have endocrine, autocrine and/or paracrine roles in ocular development. The importance of GH in ocular development is demonstrated by the ocular abnormalities that can occur in patients with pituitary GH excess or GH deficiency. Clinical and basic studies supporting roles for GH in ocular development are the focus of this brief review.     

The catecholamine response to hypoglycemia in children with isolated growth hormone deficiency syndromes and multiple pituitary hormone defects

We examined the catecholamine response to insulin-induced hypoglycemia in 46 short children evaluated for growth hormone (GH) deficiency by both pharmacologic stimulation and integrated concentration of GH. Twelve patients had quantitatively normal GH secretion by both pharmacologic stimulation and integrated concentration of GH (GHNORM). Twenty-two patients had normal GH to pharmacologic stimulation but subnormal integrated concentration of GH (GHND). Twelve patients had GH deficiency by both tests (GHD): six had isolated GH deficiency (GHD type 1) and six had multiple hormone deficiencies (GHD type 2). There was no significant difference between the peak epinephrine, norepinephrine, and cortisol responses of GH-NORM, GHND, and GHD type 1 patients. The mean peak epinephrine response of GHD type 2 patients was significantly lower (564 +/- 561 pg/ml, p less than 0.03) compared to the other patient groups. There was no significant difference between the peak norepinephrine levels between GHD type 2 patients and the remaining groups. There was no correlation between decrease in blood glucose and either increase in growth hormone, catecholamine, or cortisol concentrations. There was a significant correlation between log peak epinephrine and peak cortisol response (r = 0.53, p less than 0.0002) of the 46 subjects. Neither the basal nor stimulated catecholamine levels correlated with the integrated concentration of cortisol. We conclude that isolated GH deficiency is not associated with impairment of the catecholamine response to hypoglycemia; impairment of the epinephrine response to hypoglycemia is only associated with multiple pituitary hormone deficiencies; in children, the degree of glucose lowering is not correlated with the magnitude of peak GH, catecholamine, or cortisol responses.     

Growth hormone deficiency in Dubowitz syndrome

Severe short stature as a result of intra-uterine growth retardation is one of the characteristics of Dubowitz syndrome. There have been few reports elaborating growth hormone secretory status in this syndrome. A child with Dubowitz syndrome, who was found to have complete growth hormone (GH) deficiency and who responded to growth hormone therapy, is described. This appears to be the first documentation of GH deficiency in this syndrome.     

Growth response to growth hormone therapy following cranial irradiation

The growth response to growth hormone (GH) therapy has been studied in 12 children who received irradiation to the cranium alone either for brain gliomas, distant from the hypothalamic-pituitary axis, or as prophylaxis against CNS leukaemia. Seven children have completed GH treatment (mean duration 4 years) and five are presently on GH (mean duration 1.2 years). This response has been compared to that seen in 14 children with isolated idiopathic GH deficiency (IGHD), following GH therapy. Before treatment, the cranially irradiated patients (C-PRGHD) had higher standard deviation scores (SDS) for standing height, sitting height and leg length, and less bone age (BA) retardation, but started treatment at a similar age, and with a similar pre-treatment growth velocity and GH peak to standard provocative tests, compared to IGHD patients. GH produced a significant and similar increase in growth velocity (cm/year and SDS for BA) over the first 2 years' treatment in both groups. However C-PRGHD patients entered puberty and thus completed growth earlier than the IGHD group. As a result, cranially-irradiated children showed no change in height SDS with GH therapy, compared to catch-up growth in IGHD. Nevertheless, GH has enabled C-PRGHD patients to maintain their centile position and to achieve a more acceptable final height.Abbreviations GH growth hormone - IGHD idiopathic growth hormone deficiency - C-PRGHD post cranial-irradiation growth hormone deficiency - SDS standard deviation score - BA bone age - ALL acute lymphatic leukaemia - TSH thyroid stimulating hormone - CA chronological age - HA height age     

Therapeutic optimization of growth hormone deficiency in children and adolescents

More than 40 years after the introduction of growth hormone (GH) treatment, many questions remain unanswered. Clearly, with the availability of rhGH and with current treatment protocols, treatment efficacy has improved. However, it still remains unclear whether current treatment protocols are the best possible. Before GH deficiency was recognized as a chronic disease, children only received treatment until normal adult height had been reached. However, it has recently been shown that not all GH-dependent body structures and functions normalize in parallel with height. Furthermore, in adolescents with GH deficiency, the interruption of GH substitution leads to severe hormone deficiency symptoms in adulthood. In the case of an adolescent who meets the biochemical criteria for GH deficiency in adulthood, but does not show alterations of metabolism, body structure, or emotional state, should GH treatment be started in adolescence, or only if and when the clinical syndrome becomes apparent? This is a difficult question to which there is not yet any clear answer, and we suggest that there is a need for further studies in this area. Furthermore, it will be necessary to re-evaluate the situation of patients who have completed their growth, and definitive conclusions will require controlled studies.     

Growth hormone therapy in short stature

Unlimited availability of growth hormone (GH), and the demonstration of increased growth velocity (GV) during GH treatment in non-GH-deficient children have suggested new indications for GH therapy in short stature. There are two principle conditions with GH-related short stature: classical growth hormone deficiency (CGHD) and growth hormone neurosecretory dysfunction (GHND). Present knowledge about the effects of GH treatment in these and other disorders of short stature are reviewed. In non-CGHD, it is not possible to predict the short-term effect on growth during GH therapy, and even if GV increases, the effect on final adult height remains to be documented. This, together with potential side effects and the high expense of GH treatment, exhort to a restricted attitude towards routine GH treatment of short children without GH deficiency.     

Growth of children with β-thalassemia major

Hypertransfusion and regular chelation therapy have allowed improved survival in patients with thalassemia major (TM). Despite medical advances, growth failure and hypogonadism remain significant clinical problems in these patients in adolescence. Disproportionate truncal shortening which is common especially among adolescents with thalassemia, is due to platyspondyly resulting from a combination of factors like hemosiderosis, desferrioxamine toxicity or deficiency of trace elements. Although growth hormone (GH) deficiency and GH neurosecretory dysfunction have been described in TM patients, most short TM patients have normal GH reserve. The low serum IGF-1 and IGFBP-3 concentrations in TM patients despite having normal GH reserve and serum GH binding protein levels suggest that a state of secondary GH insensitivity exists. The pubertal growth spurt may be impaired in TM patients going through spontaneous or induced puberty and may have a negative effect on final adult height. GH therapy in dosages ranging from 0.5–1.0 IU/kg/wk has resulted in a significant improvement in growth velocity in short TM children without any adverse effects on skeletal maturation, blood pressure, glucose tolerance and serum lipids. There is limited evidence that GH treatment can result in an improved final adult height in short TM children. Careful and regular clinical and biochemical monitoring should be preformed on these patients while they are treated with GH.     

Growth hormone for short stature not due to classic growth hormone deficiency

The advent of recombinant DNA technology has resulted in potentially unlimited supplies of growth hormone. Sufficient quantities are now available not only for the long-term, uninterrupted treatment of GH-deficient children but potentially for the treatment of non-GH-deficient patients with other short stature or growth attenuating disorders. Short-term studies have demonstrated an improvement in the growth rates of subjects with isolated short stature, Turner syndrome, and chronic renal failure; and additional studies are under way to assess the efficacy of GH therapy of other short stature syndromes. However, the long-term efficacy and possible adverse effects of GH treatment in these situations is not known. Until there has been more experience, GH deficiency should remain the primary indication for GH treatment. Growth hormone should not be considered routine therapy for other conditions associated with or resulting in short stature. However, research should continue in these areas to define which children may benefit from GH treatment.     

X-linked agammaglobulinemia and isolated growth hormone deficiency

X-linked agammaglobulinemia and isolated growth hormone deficiency was first described in 1980 and then classified as a different primary immune deficiency. Delayed puberty in patients with X-linked agammaglobulinemia may result in delayed secretion of growth hormone (GH). To determine true isolated growth hormone deficiency. GH stimulation tests and other hypophyseal hormone evaluations must be performed. In this paper, we report a 15-year-old boy with X-linked agammaglobulinemia and isolated growth hormone deficiency, and review related literature.     

Transition of childhood-onset growth hormone-deficient patients to adult healthcare

In patients with childhood-onset growth hormone (GH) deficiency who have reached adult height, the transition from pediatric to adult healthcare is an appropriate time for reassessment of GH status. For patients in whom persistent GH deficiency (GHD) is established by appropriate testing, reinstitution of GH therapy or its continuation can improve quality of life, optimize body composition and bone mineral density, as well as reduce cardiovascular risks associated with GHD. Ongoing GH therapy should be individualized with attention paid to changes in serum insulin-like growth factor (IGF)-I concentrations, body composition, and occurrence of adverse effects such as edema and arthralgia. GH deficient patients who discontinue childhood GH replacement therapy and are not restarted as adults should undergo long-term surveillance to detect possible adverse consequences (e.g. reduced bone mineral density) typically associated with interruption of GH treatment.     

Kleinwuchs und Therapie

Short stature is a diagnostic challenge because of the enormous spectrum of physiological maturation and growth patterns in childhood. A carefully drawn growth chart and calculation of the familial target height are required for a correct analysis. A low growth velocity, a height below the familial target, severe short stature and disproportionate or syndromic short stature are rational reasons for referral to a growth specialist. For clinical assessment a small for gestational age (SGA) patient history, presence of minor or major anomalies and skeletal disproportions should guide the diagnostic approach. Bone age estimation may enable the differentiation between inborn (primary) and acquired (secondary) growth failure. Growth hormone (GH) stimulation tests should only be performed if GH deficiency is very likely based on the foregone diagnostics. Constitutional delay of growth and puberty should not be confused with GH deficiency. A GH therapy is effective in GH deficiency and allows a normal growth within the familial target range in the majority of treated children. In addition, the diagnosis and therapy of Turner syndrome, SGA short stature and short stature homeobox-containing gene (SHOX) deficiency are discussed.     

Growth hormone releasing hormone and growth hormone: genetic studies in familial growth hormone deficiency

Four families with growth hormone (GH) deficiency, either isolated or with other pituitary hormonal deficits are described. Members of each underwent pharmacological testing for GH secretion and infusions of GH releasing hormone (GHRH) to determine the locus of the defect in GH secretion. In addition, we have extracted DNA from white blood cells to characterize the GHRH and GH genes. All members tested had the normal complement of GH and GHRH genes. Four generations of one family with isolated GH deficiency, autosomal dominant were studied. The younger members showed minimal GH responsiveness to a single infusion of GHRH. However, the older members did not respond even after 30 doses of GHRH given intravenously every 3 h. Two members of a family with the autosomal recessive type of isolated GH deficiency had large GH increases after GHRH infusion. Thus in these families the GH secretory defect lies within the hypothalamus. Members of two families with pituitary deficiency (GH and other tropic hormones) of the autosomal recessive type had variable responses to GHRH and varying amounts of pituitary tissue seen on high resolution CT scans. Although it is not possible to delineate the precise location of the secretory defects in these latter two families, a hypothalamic defect is probable based on the responses to multiple trophic stimuli. Heterogeneity of structure and function exists within and between families with isolated GH deficiency and within and among families with pituitary deficiency. It is from the study of such families in which all members presumably have the same underlying defect that one can more readily decide on a pathogenetic mechanism.     

Laron dwarfism: growth and immunoreactive insulin following treatment with human growth hormone.

A 13 1/2-year-old boy with features of growth hormone deficiency had elevated fasting plasma GH levels (5.7 to 66 ng/ml). Serum somatomedin values remained low despite treatment with human growth hormone. Plasma GH values were suppressed following oral administration of glucose and increased following insulin-induced hypoglycemia, L-dopa, and arginine. Chlorpromazine suppressed GH, both fasting and during IIH. These results suggest that the neuroendocrine mechanisms mediating GH secretion seemed to be intact. Peak plasma insulin levels increased in response to glucose administration after HGH suggesting that GH has a direct effect on the pancreatic beta cell which is not mediated by Sm. Plasma testosterone values increased to adult male levels, but there was inadequate secondary sexual response. Growth was enhanced by HGH and may have been due to testosterone and/or insulin. Although Laron dwarfism may result from a receptor defect, an abnormality in GH structure is also possible.     

Empty sella in short children with and without hypothalamic-pituitary abnormalities

A study was conducted on growth hormone (GH) response to oral clonidine (0.15 mg/m²), GH and cortisol responses to i.m. glucagon (0.1 mg/kg), and glucose response to an oral load of glucose (1.75 g/kg). Measurements were made on the circulating concentrations of free thyroxine (FT4), thyroid stimulating hormone (TSH) and different growth parameters and CT sellar images in 25 GH deficient children (Peak GH response to clonidine and glucagon<7 ug/ml), 15 growth retarded children (Ht<5th percentile for age and gender) with sickle cell disease (SCD) and GH deficiency, 30 randomly selected children with normal variant short stature (NVSS) (HtSDS 2SD below the mean for age and gender with normal GH response to stimulation (>10 ug/ml) and 20 age-matched normal children were evaluated. Out of the 25 children with GH deficiency, five had multiple pituitary hormonal deficiency (GH<TSH and/or ACTH. deficiencies), and 20 had isolated GH deficiency. Empty sella, either complete or partial, was detected in 9 out the 20 children with isolated GH deficiency (45%), 4 out of the 5 children with multiple pituitary deficiency (80%), all the children with SCD and GH deficiency (100%), 3 out of the 30 children with NVSS (10%) and in none of the normal children. The insulin-like growth factor-1 (IGF-I) concentrations were significantly lower in the two groups of children with GH deficiency compared to those with NVSS. The height standard deviation scores (HTSDS) were significantly lower and the annual growth velocity was slower in children with idiopathic GH deficiency and empty sella compared to those with NVSS and those with empty sella associated with SCD. The bone age delay (yr) did not differ among the 3 groups of children with short stature. All children with isolated GH deficiency associated with empty sella had normal body mass indices (BMI), while all the children with SCD and empty sella had BMI below the 5th percentile for the corresponding age and gender. None of the children had glucose intolerance. In conclusion, children with growth retardation and abnormal hypothalamic pituitary functions have high incidence of empty sella. However, empty sella is detected in considerable number (10%) of short children with normal hypothalamic pituitary function.     

Growth response to growth hormone therapy following craniospinal irradiation

Nineteen (12 male, 7 female) children, who have received craniospinal irradiation for the treatment of a brain tumour distant from the hypothalamic-pituitary axis, resulting in growth hormone (GH) deficiency (CS-PRGHD), have been treated with GH. Eight have completed growth. Comparison has been made with the growth of seven untreated children, whose heights and growth rates at presentation were normal despite GH deficiency secondary to irradiation. GH produced a significant increase in growth velocity over the first 3 years' treatment in CS-PRGHD patients with a mean first year increment of 3 cm/year. Patients, treated to completion of growth, showed a significant increase in leg length standard deviation (SD) score (SDS+0.2) compared to that of the untreated (SDS–0.9) (P<0.05). Stitting height SD scores decreased irrespective of GH therapy (by -1.7 for the treated and -2.2 for the untreated). The onset of puberty in the irradiated patients occurred at a mean bone age of 10.7 years in males and 9.9 years in females. This limited the time available for GH therapy. These factors resulted in a decrease in standing height SDS of 0.9 at completion of GH therapy in CS-PRGHD, but a decrease of 1.7 in those not treated with GH. Thus GH therapy failed to induce catch-up growth in irradiated patients, but it did prevent further loss of adult stature, with a mean final height SD score of -3.4 in CS-PRGHD patients.Abbreviations GH growth hormone - CS-PRGHD post craniospinal irradiation growth hormone deficiency - change in - SDS standard deviation score - ALL acute lymphatic leukaemia - IGHD isolated growth hormone deficiency - C-PRGHD post cranial irradiation growth hormone deficiency - FSH follicle stimulating hormone - LH luteinising hormone - BA bone age - TSH thyroid stimulating hormone - CA chronological age     

Growth and endocrine disorders secondary to cranial irradiation

External cranial radiation for the treatment of malignant diseases has become a frequent cause of growth hormone deficiency (GHD). The timing of occurrence and the frequency of GHD were related to the hypothalamic-pituitary radiation dose. Frequency varied from 50% in leukemia (2400 cGy) to 75% in face and neck tumors or medulloblastoma (2500-4500 cGy) and up to 100% in optic glioma (greater than 4500 cGy). The significantly more severe growth deficit in patients with GHD given higher radiation doses suggests different levels of residual GH secretion according to radiation dosage. The minimum harmful radiation dose is probably close to 1800-2000 cGy. Our data show that stimulation tests remain a useful means of defining GHD and predicting growth. A fair agreement between GH secretion and growth was found in most cases, regardless of the radiation dose. The only exception was a group of leukemic children (2400 cGy) who achieved normal prepubertal growth despite a low GH response. The 24-h spontaneous plasma GH profiles and IGF-I measurements may add information if growth is retarded despite a normal GH response. We showed that growth retardation occurring after some schedules of total body irradiation was not due to GH deficiency but rather to radiation-induced skeletal lesions. Early or true precocious puberty, generally associated with GHD, was another cause of height loss. As the role of GH deficiency in the final height reduction was demonstrated in all groups of patients after cranial radiation, we suggest that hGH therapy should be considered in any child with proven GH deficiency and significant growth retardation after such radiation.