GH deficiency in adult B-thalassemia major patients and its relationship with IGF-1 production

Endocrine complications in Β-thalassemia represent a prominent cause of morbidity. Above all, dysfunction of GH-IGF-1 axis is of a major concern because of its pathogenic role on cardiac and bone disease, frequently described in this clinical setting. The aim of this paper is to analyze GH-IGF-1 axis in a cohort of 25 adult patients affected by Β-thalassemia. We found that GH deficiency was present in only 8% of our patients if diagnosis was based on GH peak below 9μg/L to two GH provocative tests instead of only one, and was mainly related to iron overload. On the contrary, IGF-1 production was impaired in a higher percentage of patients (72%), without significant correlation with iron burden. Of note, patients with hepatitis C virus infection showed lower IGF-1 concentrations than uninfected subjects despite a normal GH reserve, suggesting that partial GH insensitivity at the post-receptor level may play a key role in IGF-1 deficiency described in thalassemic patients.     

Comparison of adrenal function tests in children--the glucagon stimulation test allows the simultaneous assessment of adrenal function and growth hormone response in children

The accurate assessment of adrenal function is necessary in many children with suspicion of pituitary insufficiency. The objective of this study was to evaluate the adrenal response during the glucagon stimulation test (GST) and its diagnostic utility in children. A total of 290 children, aged 10.1 +/- 5.0 years, were evaluated for adrenal function using the corticotrophin releasing hormone (CRH) test, the GST, and/or the insulin tolerance test (ITT). Glucagon stimulation provoked a substantial rise in cortisol and adrenocorticotropin (ACTH) that was independent of gender, age, or underlying growth hormone deficiency. There were no differences in peak cortisol levels in the GST compared to the CRH test in pair-wise intra-individual analyses in children with both tests performed within one year (615.4 +/- 30.5 vs 602.8 +/- 22.4 nmol/l, n=52). Similarly, there were no differences in the cortisol response between the ITT and CRH test. Peak cortisol levels in the CRH test correlated with the GST and the ITT. The magnitude of ACTH response, in contrast, was highest in the ITT with a 9.8-fold increase over baseline, while the increase in the GST (3.1-fold) and CRH test (1.6-fold) were more subtle. Since there is controversy concerning reliable cut-off values for adrenal function tests in children, we analyzed cut off levels in 186 children, including 26 children with adrenal insufficiency, using the CRH test. A peak cortisol level of 450 nmol/l provided the best balance of sensitivity (88.5%) and specificity (86.8%), while higher cut-off levels did not increase sensitivity but lost in specificity. In summary, the GST constitutes an1 equally sensitive test for the assessment of adrenal function in children that is not confounded by anthropometric parameters and is generally not accompanied by major side effects. It allows the simultaneous assessment of corticotroph and somatotroph function and may thus constitute a valuable alternative to the ITT.     

Growth hormone response to a standardised exercise test in relation to puberty and stature.

Growth hormone (GH) was measured before and 10 minutes after a standardised bicycle exercise test (duration 15 minutes) in 37 short children (group 1: mean (SD) age 12.8 (3.5) years; mean (SD) bone age 10.4 (3.6) years; mean (SD) height standard deviation score (SDS) -2.8 (0.7], 16 tall children (group 2: mean age 12.9 (2.8) years; mean bone age 13.9 (1.4) years; mean height SDS 3.0 (0.8], and 30 normal children (group 3: mean age 13.3 (3.2) years; mean bone age 12.8 (3.4) years; mean height SDS -0.4 (0.8]. Results of GH are expressed as mean (SEM). The pre-exercise GH was similar in the three groups (group 1, 8.0 (2.3) mU/l, group 2, 8.5 (2.5) mU/l, and group 3, 8.3 (2.3) mU/l). There was a significant rise in GH after exercise in all three groups. GH after exercise was higher in group 2 (35.1 (2.5) mU/l) compared with groups 1 and 3 (17.8 (3.0) and (20.8 (3.2) mU/l). Post-exercise GH was less than 10 mU/l in 29 children (34% total; 49% group 1, 6% group 2, and 34% group 3). There was a positive relation between post-exercise GH and both bone age and public hair stage. Multiple regression analysis revealed that relevant predictors of a rise in GH with exercise were different for the sexes in these children with varying stature: for boys, bone age and pubic hair stage; for girls, height and height SDS. All the tall girls were in puberty. No statistical relation was observed between post-experience GH and cardiovascular response to exercise, time of day of exercise, time of eating before exercise, and plasma insulin or insulin to glucose ratio at time of exercise. We conclude that the GH response to the physiological stimulus of exercise is higher in puberty compared with childhood. Therefore, although children may be suspected of having GH deficiency after a failure of GH to increase after exercise, a non-response may be a normal finding in prepubertal children, independent of stature.     

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 response to exercise in asthmatic and normal children

Maximal growth hormone (GH) increments following exercise were compared in asthmatic (n=14) and normal (n=8) children. Exercise, which consisted of 6 min ergometer cycling while breathing cold dry (CD) air, induced asthma in all asthmatic patients but not in normal subjects. Baseline plasma GH levels were similar in both groups. Following exercise, however, asthmatic patients had significantly higher mean GH increments than normal subjects (14.8 vs 4.9 ng/ml,P<0.025). To evaluate the possible role of bronchoconstriction in the GH response all subjects exercised again, this time while breathing warm humid (WH) air. Despite the absence of exercise-induced asthma (EIA) while breathing WH air, asthmatic patients still had significantly higher mean GH increments than normal subjects (9.2 vs 2.3 ng/ml,P<0.05). We conclude that some asthmatic children show excessive GH secretion after exercise regardless of inspired air conditions or the development of EIA.     

Growth hormone release in response to growth hormone-releasing hormone in term and preterm neonates

The growth hormone response to a single intravenous dose of human growth hormone-releasing hormone (GHRH) was examined in 23 healthy neonates (12 term and 11 preterm) aged 2-4 days. There were no significant increases in growth hormone concentrations at any point in time studied following GHRH administration in either group of newborns. The mean basal growth hormone levels of term neonates were significantly higher than those of the premature newborns (39.6 +/- 5.3 vs. 23.2 +/- 3.3 ng/ml; p less than 0.01) and this difference in growth hormone remained significant 15 and 30 min after GHRH injection. Gestational age correlated positively with both basal and peak growth hormone concentrations in our patients. In conclusion, first, neonates studied in their first days of life have high basal levels of growth hormone and fail to further secrete any significant amount of growth hormone following a single dose of GHRH, and, second, premature newborns secrete significantly less growth hormone than do term neonates.     

Growth and adult height in atypical coeliac patients, with or without growth hormone deficiency

OBJECTIVE: To evaluate the effect of a gluten-free diet on growth and adult height, when available, in coeliac children without gastrointestinal symptoms. PATIENTS AND METHODS: Sixty-one coeliac children without gastro-intestinal symptoms were included in the study. The age at diagnosis was 9.50 +/- 3.3 years. Thirty-eight had short stature at diagnosis (< 10th percentile) and 23 had normal stature. Thirty-seven reached adult height. RESULTS: After beginning the diet an increase in growth velocity was seen in 30 patients (responders) (20 with initial short stature), while in 31 patients (18 with short stature) there was no catch-up growth (non-responders). Bone age at diagnosis was significantly more delayed in the responders than in the non-responders. Target height was significantly higher in children with normal stature at diagnosis than those with short stature. Growth hormone (GH) deficiency was found and confirmed after 6-12 months of diet in 12 of the 38 patients (32%) with short stature. In the group of the 30 'short' patients who attained final height, target height was attained or improved in 12 patients (40%): in eight of the 16 (50%) responders and in four of the 14 (29%) non-responders; in eight (all responders) out of 22 (36%) without GH deficiency, and in four out of eight (50%) patients with GH deficiency treated with GH (all non-responders). CONCLUSIONS: In children in whom coeliac disease is diagnosed because of short stature, a gluten-free diet will be successful if at diagnosis there is a delay of bone age and in the first year of diet there is an evident catch-up growth. When this does not occur, i.e. in half of the patients (18 out of 38), it may be because of an associated and transient GH deficiency. In these patients a period of GH replacement therapy as well as a gluten-free diet may improve their final height.     

Growth response to human growth hormone treatment in children with partial and total growth hormone deficiency

The growth response during the first and second years of human growth hormone (hGH) treatment was studied in 14 prepubertal children with so-called "partial" GH deficiency (peak GH between 8 and 15 mU/l) and compared to 28 prepubertal children with "total" GH deficiency (peak GH less than 8 mU/l). There was no difference in growth acceleration between children with partial and total GH deficiency, when initial covariables were taken into account. In a stepwise multiple regression analysis initial stature, pre-treatment growth velocity and skinfold thickness were shown to be most related to growth response, but after exclusion of 3 children with a genetic form of total GH deficiency and partial TSH deficiency this relationship was lost. GH levels during provocation tests and auxological criteria have a poor predictive value for growth response to hGH therapy.     

Stress response and its relationship to cystic (pseudofollicular) change in the definitive cortex of the adrenal gland in stillborn infants.

The adrenal glands of 41 fresh stillbirths were studied and a ''stress response'' pattern could be seen in 28. In these glands the stress response was characterised by compact cell change, lipid depletion, excess pyroninophilia, and dilatation of the very prominent granular endoplasmic reticulum. Scattered areas of cytolysis of cells, especially of the definitive cortex, gave rise to the commonly seen cystic (pseudofollicular) change and it was obvious that cells undergoing lysis were severely ''stressed''. In 2 infants there was a ''clear cell reversal'' pattern. Histological and ultrastructural changes of the stress response were not identified in 11. Infants of low birthweight score were somewhat more commonly represented in the group that did not show a stress response. Cytolytic changes accompanying a stress response were commoner in immature infants. It is argued that cystic (pseudofollicular) change in the adrenal cortex of the newborn signifies a previous stress reaction.     

Growth hormone response to GRF 1-44 in children following cranial irradiation for central nervous system tumors

The growth hormone (GH) responses to (A) GRF 1-44, 1 microgram/kg i.v., (B) L-dopa and either arginine, insulin, or glucagon, and (C) exercise were evaluated in 10 children (3 girls, 7 boys; ages 10 years to 15 years, 8 months), 2-10.75 years following cranial irradiation for medulloblastoma (8 patients), pineoblastoma (1 patient), and a fourth ventricular ependymoma (1 patient). Nine of the 10 children had abnormal growth rates. All children were euthyroid at the time of the study. The mean 0-60-min peak GH response to GRF (10.06 +/- 2.6 ng/ml) in the patients was less than the mean peak GH response (29 +/- 2.3 ng/ml) in the control children (n = 7). In 6 patients (5 with poor growth rates), a decreased GH response was noted to GRF and all other tests. Of the remaining patients, all with poor growth rates, two patients demonstrated an adequate response to GRF and pharmacologic testing; one patient had a normal GH response to GRF with a low GH response to pharmacologic testing; and one patient had a low response to GRF, despite a normal response to both exercise and pharmacologic testing. The decrease in mean peak GH response to GRF in the patient population confirms that radiation to the hypothalamic-pituitary region produces abnormalities in growth hormone release. Furthermore, in these patients, discordant GH responses to GRF and pharmacologic or physiologic tests can be observed. The abnormality in growth hormone release may result from a hypothalamic dysfunction in GRF release and/or damage to GH secretory pituicytes.     

In utero ventilation augments the left ventricular response to isoproterenol and volume loading in fetal sheep

In its normal circulatory environment, the fetal left ventricle can maximally increase output less than 2-fold, in contrast to the nearly 3-fold increase that occurs at birth. Several studies have attributed this finding to fetal myocardial "immaturity," and speculated that there is a rapid maturation of the myocardium in the perinatal period. We investigated the importance of the circulatory environment itself, rather than myocardial immaturity, by measuring left ventricular output (LVO) during in utero oxygen ventilation and isoproterenol infusion. We studied seven near-term fetal sheep greater than or equal to 2 d after placement of intravascular catheters, an endotracheal tube, and an electromagnetic flow transducer around the ascending aorta. We measured hemodynamic variables in the presence and absence of all combinations of oxygen ventilation, isoproterenol infusion, and volume infusion. Baseline LVO was normal (133 +/- 27 mL.kg-1.min-1). Individually, oxygen ventilation (136 +/- 11 mL.kg-1.min-1, p less than 0.001) and isoproterenol (48 +/- 11 mL.kg-1.min-1, p less than 0.05) increased LVO significantly; volume infusion did not. Their cumulative effect increased LVO nearly 3-fold (to 387 +/- 98 mL.kg-1.min-1), similar to levels seen in the newborn lamb. Mean left atrial pressure increased above right during oxygen ventilation (from 0.05 +/- 0.54 kPa to 0.82 +/- 0.39 kPa, p less than or equal to 0.0001). We conclude that the previously observed limitation in maximal LVO in the near-term fetus is primarily caused by its circulatory environment rather than relative myocardial immaturity, and speculate that a prominent Starling response is uncovered by decreases in left ventricular afterload and right ventricular constraint.     

Growth hormone response to hpGRF-40 in different forms of growth retardation and endocrine-metabolic diseases

The effect of one of the new human pancreatic growth hormone releasing factors (hpGRFs) was assessed in children or young adults with different forms of growth retardation or endocrine-metabolic diseases. Intravenously administered synthetic hpGRF-40 (1 g/kg) induced a clear-cut and prompt rise in plasma growth hormone (GH) levels in 8 normal prepubertal children and a definite GH rise in 11 out of 14 children with isolated GH deficiency (IGHD) and one child with the Silver-Russel syndrome. In two out of three subjects with craniopharyngioma hpGRF-40 did not induce any plasma GH increase.In seven out of ten children with constitutional growth delay (CGD), hpGRF-40 induced a biphasic GH response, with a prompt small GH increment followed by a second, more consistent rise. Both in children with IGHD and with CGD the rise in plasma GH following hpGRF-40 was markedly lower than in controls. In children with CGD the GH response to hpGRF-40 was defective, despite the fact that in most of them the GH response to standard pharmacological stimuli was normal according to generally accepted criteria.hpGRF induced a small but sustained plasma GH rise in four hypothyroid subjects, while in three out of four children with idiopathic obesity the GH response to hpGRF was strikingly reduced. These data demonstrate that hpGRF is a potent stimulus of GH release in normal prepubertal children and a physiological means of investigating GH function in diseases associated with growth impairment.Abbreviations hpGRF human pancreatic growth hormone releasing factor - IGHD isolated growth hormone deficiency - CGD costitutional growth delay - GH growth hormone - GRF growth hormone releasing factor - YR years - LHRH luteinizing hormone releasing hormone - ACTH adreno-corticotropic hormone - TRH thyrotropin releasing hormone - IU international units - SDS standard deviation score - LH lutcinizing hormone - FSH follicle stimulating hormone - TSH thyrotropin hormone - T₃ thriiodotyronine - T₄ Tyroxine - RIA radioimmunoassay - SE standard error - A adult - IBW ideal body weight - RT replacement therapy - PH primary hypothyroidism - CT computed tomography Paper presented in part at the 7th International Congress of Endocrinology, July 1–7, 1984, Quebec City, Canada     

Differences in thromboxane production between neonatal and adult platelets in response to arachidonic acid and epinephrine

In this study, we have investigated the possible role of the pro-aggregatory arachidonic acid (AA) metabolite thromboxane, in the impaired function of neonatal platelets. In platelet-rich plasma thromboxane production (measured by radioimmunoassay of thromboxane B2) was not different between neonates and adults when stimulated by thrombin (at 0.1 or 1.0 U/ml) or collagen (70 micrograms/ml) although neonatal platelets produced decreased thromboxane (TBX2) postepinephrine stimulation. In response to 1 U/ml thrombin, adult and neonatal platelet-rich plasmas produced mean values of 3.41 +/- 0.35 (SEM) and 3.11 +/- 0.49 pmol of TXB2/10(6) platelets, respectively. Production of TXB2 in response to 0.1 U/ml thrombin was not dissimilar between neonates (1.01 +/- 0.46 pmol) and adults (1.04 +/- 0.38 pmol). When collagen was used as the aggregating agent, TXB2 production was also not significantly different with values of 2.44 +/- 0.48 and 1.90 +/- 0.46 pmol/10(6) platelets produced by adult and neonatal platelet-rich plasma, respectively. In response to 200 microM epinephrine, adult platelets produced 1.03 +/- 0.39 pmol TXB2/10(6) platelets while neonatal platelet TXB2 production was significantly decreased (0.15 +/- 0.04; P less than 0.05). Thromboxane production in response to AA, however, was markedly elevated in neonatal platelet-rich plasma. When 200 and 400 microM concentrations of AA were used as the aggregating stimuli, neonatal platelet rich plasma produced 3.17 +/- 0.77 and 8.0 +/- 1.47 pmol TXB2/10(6) platelets, respectively. These values were significantly elevated P less than 0.02 and less than 0.005) when compared to mean values of 0.41 +/- 0.10 and 3.32 +/- 0.15 pmol in adult platelet-rich plasma.(ABSTRACT TRUNCATED AT 250 WORDS)