Short children with familial short stature show enhancement of somatotroph secretion but normal IGF-I levels

The aim of the present study was to evaluate the GH status in children with familial, idiopathic short stature (FSS). To this goal we evaluated the GH response to GHRH (1 microg/kg iv) + arginine (ARG) (0.5 g/kg iv) test which is one of the most potent and reproducible provocative tests of somatotroph secretion, in 67 children with FSS [50 boys and 17 girls, age 10.8+/-0.4 yr, pubertal stages I-III, height between -3.6 and -1.6 standard deviation score (SDS), target height <10 degrees centile, normality of both spontaneous and stimulated GH secretion as well as of IGF-I levels]. The results in FSS were compared with those in groups of children of normal height (NHC) (42 NHC, 35 boys and 7 girls, age 12.0+/-0.5 yr, pubertal stages I-III, height between -1.3 and 1.4 SDS, height velocity standard deviation score (HVSDS)>25 degrees centile, GH peak >20 microg/l after GHRH+ARG test, mean GH concentration [mGHc]>3 microg/l) and children with organic GH deficiency (GHD) (38 GHD, 29 boys and 9 girls, age 11.2+/-3.7 yr, pubertal stages I-III, height between -5.7 and -1.3 SDS, GH peak <20 microg/l after GHRH +ARG test, mGHc <3 mg/l). Basal IGF-I levels and mGHc were also evaluated in each group over 8 nocturnal hours. IGF-I levels in FSS (209.2+/-15.6 microg/l) were similar to those in NHC (237.2+/-17.2 microg/l) and both were higher (p<0.0001) than those in GHD (72.0+/-4.0 microg/l). The GH response to GHRH +ARG test in FSS (peak: 66.4+/-5.6 microg/l) was very marked and higher (p<0.01) than that in NHC (53.3+/-4.5 microg/l) which, in turn, was higher (p<0.01) than in GHD (8.2+/-0.8 microg/l). Similarly, the mGHc in FSS was higher than in NHC (6.7+/-0.5 microg/l vs 5.1+/-0.7 microg/l, p<0.05) which, in turn, was higher than in GHD (1.5+/-0.2 microg/l, p<0.0001). In conclusion, our present study demonstrates that short children with FSS show enhancement of both basal and stimulated GH secretion but normal IGF-I levels. These findings suggest that increased somatotroph function would be devoted to maintain normal IGF-I levels thus reflecting a slight impairment of peripheral GH sensitivity in FSS.     

Reference values of IGF-I in children from birth to 5 years of age, in Burkina Faso, using blood samples on filter paper

OBJECTIVES: The aims of this study were to validate the use of filter paper to measure insulin-like growth factor-I (IGF-I) and to establish normal levels of IGF-I in children appearing healthy, from birth to 5 years of age in an African population. METHODS: We determined IGF-I from blood collected on filter paper. We validated this method by comparing the IGF-I values from dried blood spots on filter paper (kept at 4 degrees C and ambient temperature) and from serum among 13 children under 5. IGF-I were measured by the classical IGF-I RIA, after separation of the IGF-I from its binding proteins, using Sep-Pak chromatography. To establish normal levels of IGF-I, we conducted a cross-sectional study and collected blood samples with filter paper among 360 children in Ouagadougou (Burkina Faso). RESULTS: IGF-I determined from dried blood spots on filter paper were in good agreement with IGF-I levels obtained from blood serum, whether the filter papers were kept at 4 degrees C or at ambient temperature. The results of IGF-I-levels in apparently healthy children showed that geometric mean IGF-I ranged from 27 microg/l in boys younger than five months to 31 microg/l in 5-year-old boys. In girls, mean IGF-I ranged from 29 microg/l for girls younger than five months to 45 microg/l at the age of 5. From birth to 24 months, IGF-I decreased by 0.32+/-0.08 microg/l/month in boys and by 0.27+/-0.06 microg/l/month in girls and these decreases were not significantly different (p=0.95). After the age of 24 months, there was an increase in IGF-I of 4.9+/-1.3 microg/l/year in boys and of 8.4+/-0.8 microg/l/year in girls. This increase was indeed significantly different (p<0.001). CONCLUSIONS: Reference values of IGF-I for African boys and girls were determined. They will be used for endocrine evaluations and nutritional monitoring.     

Serum leptin concentration, body composition, and gonadal hormones during puberty.

BACKGROUND: Recent evidence has suggested that leptin concentration is associated with gonadal hormone levels, and that changes in leptin concentration may trigger the onset of reproductive function in children. However, the concurrent changes in body composition during puberty make the independent associations between leptin and gonadal hormone concentrations in children difficult to resolve. METHODS: To investigate the nature of associations between leptin levels and pubertal maturation, serum concentrations of leptin, estradiol, and testosterone and body composition measures were examined in a sample of 152 healthy pre-pubertal, pubertal, and post-pubertal children. RESULTS: Leptin concentration was nearly three-fold higher in post-pubertal girls than in pre-pubertal girls, but was relatively similar in pre- and post-pubertal boys. Significant sex differences in leptin concentration existed in prepubertal, pubertal and post-pubertal children, and these remained significant after controlling for adiposity. After adjusting for total body fat, fat-free mass and age, testosterone concentration was negatively associated with leptin levels in pubertal boys, while estradiol concentration was positively associated with leptin level in pubertal girls. CONCLUSIONS: Girls have higher serum leptin concentration before, during, and after puberty than boys, even after accounting for the development of greater female adiposity. Although other factors may be involved, sexual dimorphism in leptin concentrations during puberty appears to be partly due to a stimulatory effect of estradiol on leptin concentration in females and a suppressive effect of testosterone on leptin concentration in males.     

Normative data for adiponectin, resistin, interleukin 6, and leptin/receptor ratio in a healthy Spanish pediatric population: relationship with sex steroids

OBJECTIVES: To investigate the circulating levels of adiponectin, resistin, interleukin 6 (IL-6), and leptin/receptor ratio in healthy Spanish children throughout the different stages of pubertal development. To analyze the relationship between adipokines and sex steroid level changes during puberty. STUDY DESIGN: Serum adiponectin, resistin, IL-6 levels, and leptin/receptor ratio were studied in 160 healthy Spanish children grouped according to their pubertal stage (Tanner I, 23 girls and 22 boys; Tanner II, 19 girls and 16 boys; Tanners III and IV, 21 girls and 20 boys; and Tanner V, 20 girls and 19 boys). In addition, circulating levels of sex hormone-binding globulin (SHBG) were determined in every subject, and testosterone and estradiol levels in boys and girls respectively. RESULTS: Adiponectin levels decreased in boys from mid puberty (P < 0.05) to become significantly lower than in girls (P < 0.001), whereas IL-6 decreased in both sexes (P < 0.05). Resistin levels and leptin/receptor ratio showed no differences between sexes or according to pubertal stage, except in adult females, who had the highest levels of both parameters (P < 0.001). Serum IL-6 levels correlated significantly (P < 0.05) with testosterone and estradiol levels (r=-0.37 and -0.42 respectively), whereas estradiol, but not testosterone, correlated with leptin/receptor ratio (r=0.59; P < 0.001). Furthermore, a positive relationship was found between SHBG and adiponectin and IL-6 (P < 0.001 and P < 0.05 respectively). In addition, a direct correlation between leptin/receptor and body mass index was found in both sexes (P < 0.001). CONCLUSION: Variations in adipokine profiles throughout pubertal development appear to be related with progression of gonadal function.     

Effect of sex hormone administration on circulating ghrelin levels in peripubertal children

BACKGROUND: Ghrelin levels gradually decrease throughout childhood and with advancing pubertal stage. The change during puberty is more pronounced in boys than girls. OBJECTIVE: The objective of the study was to investigate whether the pubertal drop in ghrelin secretion is modified by the increase in sex hormones. PATIENTS AND METHODS: Ghrelin levels were measured in 34 short peripubertal children (17 boys and 17 girls) aged 8-12.5 yr before and after sex hormone priming for GH stimulation testing. RESULTS: In boys, priming with testosterone increased testosterone to pubertal levels (23.7 +/- 7.1 nmol/liter), which in turn induced a marked decrease in ghrelin (from 1615.8 +/- 418.6 to 1390.0 +/- 352.0 pg/ml) and leptin (from 8.0 +/- 4.5 to 5.8 +/- 3.2 ng/ml) and an increase in IGF-I (from 162.7 +/- 52.8 to 291.1 +/- 101.6 ng/ml) (P < 0.001 for all parameters). In girls, priming with estrogen led to a supraphysiological increase in estradiol levels (1313.8 +/- 438.0 pmol/liter), which had no effect on ghrelin, leptin, or IGF-I. There was no correlation between ghrelin levels and levels of sex hormones, leptin, or body mass index in either boys or girls. CONCLUSIONS: A pharmacological increase in sex hormones is associated with a marked decline in circulating levels of ghrelin in boys but not girls. Additional longitudinal studies through puberty are needed to elucidate the physiological interaction between sex hormones and ghrelin.     

Leptin levels show diurnal variation throughout puberty in healthy children, and follow a gender-specific pattern.

OBJECTIVE: To investigate the levels and diurnal rhythm of serum leptin in healthy children, and to investigate the association between leptin levels and sex steroids. METHODS: Four girls and four boys, all healthy volunteers, were followed longitudinally throughout puberty. Their chronological ages ranged from 8.7 to 19.5 years, and body composition, expressed as weight-for-height standard deviation scores (SDS), ranged between -1.7 and +2.4. Serum leptin, oestradiol and testosterone concentrations were measured by radioimmunoassay at 1000, 1400, 1800, 2200, 0200 and 0600 h. RESULTS: In all girls and boys, both prepubertally and during pubertal development, serum leptin levels increased during the night, with no difference in relative peak amplitude. In boys, the leptin concentrations increased until the initiation of puberty and then declined, whereas in girls, the concentrations increased throughout puberty. The inter-individual variation in mean leptin levels among girls decreased to 11% at the time of menarche. A positive correlation was found for both oestradiol and testosterone versus leptin in girls throughout puberty (r=0.64 and r=0.71 respectively, P<0.001). A negative correlation was found between leptin and testosterone in boys in mid- and late puberty (r=-0.66, P<0.01). No correlation was found between oestradiol and leptin in boys or between testosterone and leptin in pre- and early pubertal boys. CONCLUSION: Serum leptin concentrations show diurnal variation throughout pubertal development in both girls and boys. The changes in leptin levels during puberty follow a gender-specific pattern, probably due to an influence of sex steroids on leptin production.     

Central precocious puberty: clinical and laboratory features

OBJECTIVE: To determine whether the initial presentation of patients with central precocious puberty (CPP) varies according to the aetiology, whether this permits the differentiation between idiopathic and organic forms, and whether the body mass index (BMI) and plasma leptin concentrations are linked to gonadotrophin secretion. DESIGN: The clinical and laboratory features of 256 patients (26 boys and 230 girls) with CPP were studied separately in boys and girls. We compared patients with idiopathic CPP (seven boys and 186 girls) to those with organic CPP, whose pubertal development revealed a central nervous system (CNS) lesion (five boys and 11 girls), and to patients with organic CPP associated with a previously treated CNS lesion (14 boys and 33 girls). RESULTS: Boys with organic CPP, having revealed or treated CNS lesions, started their puberty earlier (3.0 +/- 1.0 years and 6.7 +/- 0.5 years) than boys with idiopathic CPP (8.5 +/- 0.2 years, P < 0.01 and < 0.05). Boys with organic CPP associated with a treated CNS lesion had lower luteinizing hormone (LH)/follicle stimulating hormone (FSH) peaks ratio after stimulation with gonadotrophin releasing hormone (GnRH) (1.6 +/- 0.5) than did boys with idiopathic CPP (2.2 +/- 0.3, P < 0.05). Girls with organic CPP revealing a CNS lesion started their puberty earlier (3.6 +/- 0.9 years) than girls with idiopathic CPP (6.6 +/- 0.1 years, P < 0.0 l) and had higher LH (P < 0.01) and FSH peaks (< 0.05). Girls with organic CPP associated with a treated CNS lesion had higher BMI (1.8 +/- 0.2 z-score) than did girls with idiopathic CPP (1.3 +/- 0.1 zs, P < 0.05), higher leptin concentrations (11.7 +/- 1.8 microg/l vs. 7.7 +/- 0.5 microg/l, P < 0.0 l), LH peak (P < 0.01), FSH peak (P < 0.05) and LH/FSH peaks ratio (1 +/- 0.1 vs. 0.8 +/- 0.1, P < 0.05). Only 12.4% of the girls with idiopathic CPP had BMI-zs < 0, and their plasma leptins were positively correlated with BMI (P < 0.0001). CONCLUSIONS: The features of central precocious puberty vary according to the aetiology, but it is impossible to exclude a central nervous system lesion in a given patient with central precocious puberty without performing central nervous system imaging. This imaging remains necessary in all cases of central precocious puberty. Most of the girls with idiopathic central precocious puberty had increased BMI, but we found no correlation between plasma leptin concentrations and gonadotrophin secretion.     

Serum leptin levels in males with delayed puberty during short-term pulsatile GnRH administration

Leptin may be a possible trigger for puberty. In normal males, it has been shown that leptin increases from the pre-pubertal to the early pubertal stage, and then declines in the late pubertal stage. We examined leptin levels in six male adolescents (mean age 16.3+/-0.6 yr; range 14.2-17.6 yr) with delayed puberty (constitutional delay of puberty no.=2; idiopathic hypogonadotropic hypogonadism no.=4) during 120 days of subcutaneous pulsatile GnRH administration. A group of subjects in pre-puberty (no.=11), early-puberty (n=10) and mid-puberty (no.=7) were evaluated as controls. Morning blood samples were taken for determination of leptin, testosterone, LH and FSH levels. In delayed puberty subjects blood samples were taken every 30 days after the start of GnRH administration. At each examination BMI and testicular volume were evaluated. A follow-up examination was performed in the 6 patients 1.3-7.5 yr after the end of the 120 days of GnRH therapy. At baseline evaluation in delayed puberty mean leptin levels were 11.3+/-2.0 microg/l (median 11.3 microg/l; range 4.7-17.3 microg/l) and were higher than those found in pre-puberty (p=0.04) and mid-puberty (p=0.001). During GnRH administration there was no change in BMI and leptin levels but there was an increase in gonadotrophin levels, testosterone and testicular volume. One hundred and twenty days after, mean serum leptin were 10.1+/-2.1 microg/l (median 9.1 microg/l; range 3.4-16.8 microg/l). At the end of the study, leptin levels were higher in delayed puberty than in mid-puberty (p=0.002). At the follow-up examination leptin levels were 4.3+/-1.3 microg/l (median 3.4 microg/l; range 1.4-9.1 microg/l) (p=0.03 vs end of 120 days GnRH therapy) while testosterone and BMI were not changed. In conclusion 120-day pulsatile GnRH administration induced in males with delayed puberty physiological-like pubertal changes but not the decline in leptin levels reported during the progression of puberty. Therefore, in males with delayed puberty an impairment in the phenomenon of leptin decline associated with progression of puberty could be suggested. However after retrospective diagnosis of pubertal delay and long-term therapy in subjects with idiopathic hypogonadotropic hypogonadism leptin levels declined. These data seem to indicate that time more than increase in testosterone levels and testicular volume is the determinant of leptin decline at puberty.     

Pubertal and gender-related changes in the sympathoadrenal system in healthy children

A critical amount of body fat is necessary for the initiation of puberty, and leptin, an adipocyte-derived hormone, is necessary for pubertal development. The sympathoadrenal system modulates body fat stores and leptin secretion and interacts with adrenocortical androgen production, suggesting a possible role in sexual maturation. We studied sympathetic nerve and adrenomedullary activity at rest in 80 healthy children (ages, 5-17 yr; 37 boys and 43 girls) in relation to age, pubertal stage, gender, physical activity, body mass index, and serum levels of sex steroids, dehydroepiandrosterone sulfate, cortisol, leptin, and insulin. Plasma concentrations of the adrenomedullary hormone, epinephrine (E), and its metabolite metanephrine (MN), decreased significantly with advancing puberty and were higher in boys than in girls. E and MN correlated significantly and inversely with dehydroepiandrosterone sulfate, estradiol, testosterone, leptin, and insulin. Plasma norepinephrine, which is primarily derived from sympathetic nerve endings, increased significantly with advancing puberty and increasing testosterone levels in boys. Stepwise multiple regression analysis revealed that E was best predicted by pubertal stage and leptin, and MN by estradiol and leptin. Our data suggest that sympathoadrenal hormones may play a role in the complex process of sexual maturation. Further studies are needed to investigate a possible modulatory role of the adrenal medulla in the body weight-related timing of adrenarche and/or gonadarche.     

Body mass, plasma leptin, glucose, insulin and C-peptide in offspring of diabetic and non-diabetic mothers.

OBJECTIVE: The aim was to investigate the relationship between body mass index (BMI), plasma leptin, glucose, insulin and C-peptide levels in the offspring of diabetic mothers (DM) and non-diabetic healthy mothers (HM). DESIGN: Seventy-two offspring (37 girls and 35 boys, age 4-20 years) of DM were investigated in a prospective study. Those 14-16 years old (Tanner stage II-IV) were compared with age-matched offspring of HM (33 girls and 33 boys). RESULTS: BMI strongly correlated with plasma leptin concentration in the offspring of both DM and HM children. There were higher BMI and plasma leptin and glucose levels in DM than in HM children. There was no difference in plasma insulin or C-peptide levels between HM and age-matched DM children. There was a highly significant positive correlation between plasma leptin and C-peptide in boys of DM. CONCLUSIONS: The higher plasma leptin found in the offspring of DM reflects their higher BMI. A moderately high but still normal glycemia might be a preclinical sign of insulin resistance or other disturbance of glucoregulation.     

Elevated leptin levels are associated with excess gains in fat mass in girls, but not boys, with type 1 diabetes: longitudinal study during adolescence

Adolescents, in particular girls, with type 1 diabetes may gain excessive weight during puberty. We present the results of a longitudinal study aimed to determine the roles of leptin and insulin in changes in body composition in subjects with type 1 diabetes and controls. Forty-six children (23 boys) with type 1 diabetes and 40 controls (20 boys) were followed from 8-17 yr of age. Height, weight, and sc skinfolds were assessed every 6 months, and a blood sample taken for leptin determination. Throughout the age range, body mass index (mean +/- SEM) was greater by 1.45 +/- 0.69 kg/m(2) in girls and 1.46 +/- 0.55 kg/m(2) in boys with type 1 diabetes compared with control values. In girls with type 1 diabetes, this reflected greater percent body fat (3.2 +/- 1.0%; P = 0.002), whereas in boys it related to differences in fat-free mass. Both boys and girls with type 1 diabetes had higher leptin levels adjusted for percent body fat than controls; in the girls this was related to insulin dose (regression coefficient B = 0.006 +/- 0.003; P = 0.04) and greater gains in fat mass. Hyperinsulinemia and raised leptin levels are associated with gains in fat mass throughout puberty in girls, but not boys, with type 1 diabetes.     

Treatment of chronic cough in children with montelukast,a leukotriene receptor antagonist.

Twenty-two children (13 boys and 9 girls) with chronic cough were treated with the leukotriene receptor antagonist montelukast (Singulair tbl. 5 mg) administered once daily for four weeks. In 14 children (68%), the cough ceased during the third week of treatment. Children responding to montelukast were found to have higher blood levels of eosinophil cationic protein (S-ECP) in the pretreatment blood sample than children with no response (responders 14.88+/-2.651 microg/l versus nonresponders 6.62+/-0.948 microg/l; p<0.01). Blood S-ECP levels remained higher also in the post-treatment blood sample in responders (10.55+/-1.631 microg/l) compared to nonresponders (6.13+/-0.937 microg/l; p<0.05). The difference is statistically significant. There were also differences in absolute eosinophil blood count and IgE blood levels between the two groups in the pretreatment blood sample. Using 24-hour pH-metry, two children not responding to therapy were subsequently diagnosed to have gastroesophageal reflux. Judging from the results, one might deduct that patients with chronic cough who have increased levels of serum ECP and absolute eosinophil blood counts are likely to benefit from treatment with montelukast.     

Body composition, fasting leptin, and sex steroid administration determine GH sensitivity in peripubertal short children.

Serum IGF-I levels in GH-treated subjects demonstrate a wide range of responsiveness to GH. However, the factors influencing GH sensitivity are not well known. The aim of this work was 1) to test whether body composition (determined by dual energy x-ray absorptiometry) or factors related to body composition (fasting blood glucose, FFA, C-peptide, leptin, and insulin sensitivity determined by an insulin tolerance test) influence GH sensitivity; and 2) to study the effect of sex steroid priming on GH sensitivity. We measured serum IGF-I at baseline and 24 h after a single administration of GH (2 mg/m(2)) in 60 healthy prepubertal and early pubertal children (height, -2.1 +/- 1.0 SD score). GH sensitivity, as estimated by the increase in serum IGF-I after GH administration (difference between stimulated and baseline serum IGF-I = delta IGF-I), was also determined after a short-term administration of oral ethinyl E2 in girls and im T in boys. The serum IGF-I concentration was 297 +/- 114 microg/liter at baseline and increased to 429 +/- 160 microg/liter, corresponding to a 46 +/- 29% increase over the baseline value (P < 0.0001, stimulated vs. baseline serum IGF-I). delta IGF-I was not different between gender or pubertal stage. There were positive correlations (P < 0.001) between delta IGF-I and adiposity (total body fat, r = 0.62; trunk fat, r = 0.62), fasting leptin (r = 0.64), and C-peptide (r = 0.54), and a negative correlation with fasting FFA (r = -0.33; P < 0.05) even after adjustment for age, gender, and pubertal stage. These factors remained significant independent predictors of the absolute as well as the percent increase in serum IGF-I in multiple regression analyses. Priming with T and ethinyl E2 had a similar stimulating effect on the serum GH peak in response to the insulin tolerance test. In boys, serum baseline IGF-I increased by 60%, and delta IGF-I was similar after vs. before T administration. By contrast, in girls, serum baseline IGF-I was similar, and delta IGF-I was 60% less after vs. before ethinyl E2 administration. This study indicates that 1) GH sensitivity is determined by fat mass, serum fasting leptin, C-peptide, and FFA; and 2) oral ethinyl E2 and im T have divergent effects on the IGF-I response to a single administration of GH.     

Elevated levels of leptin and insulin but not of TNF alpha are associated with hypertension in type 2 diabetic males.

Leptin and TNF alpha are thought to influence blood pressure. Therefore, the aim of our study was to investigate leptin and TNF alpha levels and their association with blood pressure, sex steroids, insulin, creatinine and lipids in type 2 diabetic patients. In 424 type 2 diabetic patients (79 hypertensive females [+Hf], 79 normotensive females [-Hf]; 133 hypertensive males [+Hm], 133 normotensive males [-Hm]) matched for sex, age and BMI serum leptin levels were measured by RIA and TNF alpha, insulin, estradiol, progesterone by ELISA as well as free testosterone by RIA. Leptin levels were comparable in +Hf and -Hf (16.5 +/- 1.0 microg/l vs 16.3 +/- 1.0 microg/l) but higher in +Hm as compared to -Hm (8.3 +/- 0.47 microg/l vs 6.5 +/- 0.34 microg/l; p<0.05). In addition, in comparison to -Hm serum levels of insulin (190 +/- 10 pmol/l vs 161 +/- 11 pmol/l; p< 0.005) and also of creatinine (118.6 +/- 3.6 micromol/l vs 101.7 +/- 2.3; p< 0.0001) were higher in +Hm. Pearson's Correlation coefficient revealed a positive correlation between levels of leptin and diastolic blood pressure (p<0.05) and also between leptin and insulin (p<0.001) in males, however, only before correction for BMI. No correlation between leptin and creatinine was found in males and females. Levels of TNF alpha were comparable in all subgroups. No correlation between levels of TNF alpha and serum leptin levels, blood pressure and insulin was found. In females TNF alpha was positively correlated with creatinine (p<0.001) and in males positively with progesterone (p<0.001). Taken together, higher serum leptin levels were found in hypertensive type 2 diabetic males as compared to normotensives, which may be related to the BMI and higher levels of insulin. These findings are accompanied by a trend to lower levels of free testosterone in hypertensive type 2 diabetic males. TNF alpha levels were comparable in female and male hypertensive and normotensive type 2 diabetic subjects.     

Changes in serum leptin concentration during behavioral therapy in obese children

To determine the pathophysiological implications of serum leptin level in obesity, we monitored the changes in serum leptin level during outpatient treatment with life style modification in children. Fifty-five obese Japanese children (34 boys and 21 girls; mean age, 9.64 years) were studied. The control children consisted of 42 nonobese subjects (27 boys and 15 girls). The serum leptin concentration was 4.35 +/- 0.46 ng/ml (mean +/- SEM) in the control girls and 2.93 +/- 0.21 ng/ml in the control boys. The serum leptin concentrations in the obese boys and girls were higher than those in their lean counterparts. The concentration in the obese boys (16.28 +/- 1.41 ng/ml) was similar to that in the obese girls (20.33 +/- 2.0 ng/ml). The logarithmic value of serum leptin concentration at the first blood sampling in obese children was correlated with percent overweight and percent body fat. In 36 obese children (24 boys and 12 girls) whose serum leptin concentrations were monitored serially during treatment of obesity, the percent overweight was significantly decreased after the initial sampling. In each individual, the changes in leptin concentration were roughly parallel to those in percent overweight. The ratio of the leptin concentration at the second blood sampling divided by the one at the first sampling in each individual was closely correlated with the respective delta percent overweight. These results suggest that the preceding course of obesity determines the serum leptin level of obese children on longitudinal basis, and that the leptin level reflects the degree of obesity on cross-sectional basis.     

Relationship between plasminogen activator inhibitor-1 antigen, leptin, and fat mass in obese children and adolescents

Hyperleptinemia may be associated with cardiovascular risk and is linked with parameters of fibrinolytic processes in adults. We studied whether body fatness, leptin, and insulin interact with plasminogen activator inhibitor-1 antigen (PAI-1-Ag) and tissue-type plasminogen activator antigen (tPA-Ag) in obese children and adolescents. Twenty-three boys (mean +/- SD: age, 10.7 +/- 3.3 years; body mass index [BMI], 28.7 +/- 5.4 Kg/m2) and 19 girls (age, 11.9 +/- 2.7 years; BMI, 29.4 +/- 4.8 Kg/m2) were investigated. Body fat mass (FM) in the children was calculated by bioelectrical impedance analysis, and blood samples were obtained for leptin, insulin, C-peptide, PAI-1-Ag, and tPA-Ag. The children were divided into 3 subgroups according to maturation. Maturity was associated with greater adiposity and higher levels of leptin and C-peptide, but insulin and PAI-1-Ag were not different between prepubertal, pubertal, and late/postpubertal children. PAI-1-Ag was associated with leptin and insulin, but not after adjustment for fatness. PAI-1-Ag was independently associated with tPA-Ag (r = .36, P < .02). Multiple regression analysis showed that tPA-Ag failed to reach the level of significance (P = .07), but FM contributed to the variation in PAI-1-Ag (adjusted R2 = .29). The BMI was the main determinant for the variation in leptin (adjusted R2 = .386) and in insulin (adjusted R2 = .60, all P < .001). Neither gender, maturation, chronological age, or leptin contributed significantly to the variation in either PAI-1-Ag or tPA-Ag. Our data suggest that adiposity and other variables contribute to higher levels of PAI-1-Ag. Leptin seems not to be independently linked with fibrinolytic parameters, but an unfavorable metabolic and fibrinolytic risk profile might emanate from the obese pubertal stage.     

Circulating adipocytokines in non-diabetic and Type 1 diabetic children: relationship to insulin therapy, glycaemic control and pubertal development.

AIM: To determine the influence of Type 1 diabetes mellitus on circulating adipocytokines in children. METHODS: The circulating concentrations of leptin, adiponectin, resistin and tumour necrosis factor (TNF)-alpha were measured in 91 children, aged 11.1 +/- 2.7 years, with Type 1 diabetes mellitus (T1DM). Ninety-one healthy children were selected as control subjects. RESULTS: Body mass index-adjusted leptin concentrations were higher in the pubertal diabetic children compared with the control children. There was a significant positive correlation between leptin and daily insulin dose in the diabetic group. Circulating adiponectin concentrations were higher in the prepubertal diabetic children and were positively associated with HbA(1c). Resistin concentrations were lower in the prepubertal non-diabetic subjects compared with the pubertal non-diabetic children, whose values were higher than those of the diabetic children. TNF-alpha concentrations were similar in non-diabetic and diabetic children. CONCLUSIONS: Circulating concentrations of adipocytokines are abnormal in Type 1 diabetic children, although the direction of change differs by cytokine. Pubertal development, in addition to insulin treatment and glycaemic control, also influences the concentrations.     

Reduction of the pituitary GH releasable pool in short children with GH neurosecretory dysfunction

OBJECTIVES: The classical 'GH neurosecretory dysfunction' (GHNSD) refers to slowly growing children with normal GH responses to classical provocative tests but impaired spontaneous GH secretion over 24 h frequently leading to low IGF-I levels. Thus it has been assumed that these subjects have insufficiency of spontaneous GH secretion due to neuroendocrine abnormalities in spite of a normal releasable pool of GH. However, classical provocative tests do not reliably assess the maximal somatotroph capacity; thus it is still unclear if the GH pool is really preserved or not. GHRH + arginine test is more potent than the classical tests and evaluates the maximal secretory capacity of somatotroph cells. The GH response to this stimulus is reproducible and also independent of age and puberty. DESIGN AND PATIENTS: We studied the GH response to GHRH (1 microgram/kg iv) + arginine (ARG, 0.5 g/kg iv) in 19 short children with GHNSD (14 boys and 5 girls, age: 12.1 +/- 0.7 years, pubertal stages I-III, HV-SDS between -1.6 and -4.9; GH peak > 10 micrograms/l after classical stimuli but mean GH concentration (mGHc) < 3 micrograms/l). The results in GHNSD were compared with those in 38 short children with idiopathic or organic severe GHD (GHD, 29 boys and 9 girls, age: 11.2 +/- 0.6 years, pubertal stages I-III, HV-SDS between -1.8 and -4.4; GH peak < 10 micrograms/l after 2 classical provocative tests) and in 83 children with normal or familial short stature (NC, 59 boys and 24 girls, age: 11.5 +/- 0.3 years., pubertal stages I-III; HV-SDS > 25th centile, normal IGF-I levels). RESULTS: Mean IGF-I levels in GHNSD (121.9 +/- 20.3 micrograms/l) were lower (P < 0.001) than those in NC (270.3 +/- 13.8 micrograms/l) but higher (P < 0.001) than those in GHD (72.0 +/- 4.0 micrograms/l). The mean GH concentration (mGHc) in GHNSD (2.1 +/- 0.1 micrograms/l) was lower (P < 0.01) than that in NC (4.9 +/- 0.5 micrograms/l) but higher (P < 0.01) than that in GHD (1.5 +/- 0.2 micrograms/l). On the other hand, the mean peak GH response to GHRH + ARG in GHNSD (43.7 +/- 3.7 micrograms/l) was markedly higher (P < 0.001) than that in GHD (8.2 +/- 0.9 micrograms/l) but significantly lower (P < 0.01) than that in NC (60. 4 +/- 2.7 micrograms/l). All GHD patients had peak GH responses to GHRH + ARG below the 3rd centile limit of normality (20 micrograms/l), while all GHNSD patients had peak GH responses within the normal range. No significant correlation was found between GH peak after GHRH + ARG, mGHc and IGF-I levels in each group. CONCLUSION: Our study demonstrates that short children with 'GH neurosecretory dysfunction' show reduction in the GH releasable pool evaluated by the provocative and potent GHRH + arginine test. However, the peak GH response to a single GHRH + arginine test in GH neurosecretory dysfunction is always within the normal range indicating that this test as well as classical stimuli does not distinguish normal subjects from GH neurosecretory dysfunction.     

Serum levels of leptin and changes during the course of recovery from diabetic ketoacidosis

Secretion of leptin, the obese gene product, is stimulated by insulin and glucocorticoids and reduced by fasting. In subjects with diabetic ketoacidosis (DKA), severe insulinopenia and prolonged fasting might cause a decrease in serum leptin levels, and subsequent insulin therapy would reverse the decrease. Otherwise, some other confounding factors, neither insulin nor fasting, might affect serum leptin levels in patients with DKA. The present study was undertaken to address these issues. Eleven patients with type 1 diabetes mellitus (seven males and four females, aged 44+/-6 years, mean +/- SEM), admitted to Jichi Medical School Hospital presenting DKA, were studied during the therapeutic period. Thirty-five sex-, age- and body mass index-matched healthy subjects served as controls. Serum leptin levels at the hospitalization were significantly greater than those of the matched control subjects (5.5+/-1.0 vs. 3.2+/-0.3 microg/l, P < 0.01). After the start of therapy with a small dose of short-acting insulin and a large volume of fluid infusion, serum leptin concentrations further increased to 10.6+/-3.6 microg/l at 24 h, and thereafter the concentrations gradually decreased and normalized at the discharge (3.3+/-0.7 microg/l, day 24+/-4). The peak levels at 24 h were significantly higher than the levels at the discharge (P < 0.05), and also +77+/-34% higher than those at the hospitalization (P < 0.005). Serum cortisol levels (1830+/-200 nmol/l) were markedly elevated at hospitalization. These results indicate that serum leptin levels are increased even under insulinopenia and fasting in the patients with DKA. Such a finding may be associated with marked hyperglycemia or enhanced secretion of glucocorticoid hormone, although the exact mechanisms remain to be elucidated. We speculate that leptin may serve as a stress peptide in DKA, but further analysis is necessary to explore a physiological role of leptin in DKA.     

Relationship of plasma growth hormone-releasing hormone levels to pubertal changes

Basal plasma GH-releasing hormone (GHRH) concentrations were measured by RIA in 180 normal subjects (93 boys and 87 girls between the ages of 8 and 18 yr). Every subject was in good health and between -2 and +2 SD for height. Fourteen boys with delayed puberty also were studied. Plasma GHRH concentrations were higher during puberty than before it. At midpuberty, the mean GHRH levels in girls was 159.1 +/- 28.5 (+/- SEM) pg/ml, approximately 5-fold higher than the level in prepubertal girls (30.3 +/- 4.3 pg/ml). The mean plasma GHRH in midpubertal boys (101.4 +/- 11.5 pg/ml) was approximately 2-fold higher than the level in prepubertal boys (48.1 +/- 5.2 pg/ml). The GHRH levels in boys with delayed puberty more closely resembled those in boys at a similar pubertal stage than those in boys of similar chronological age. The dramatic rise in plasma GHRH levels during puberty suggests a role for this peptide in the adolescent growth spurt. Moreover, these data indicate that GHRH levels during adolescence may be a marker of the patient's pubertal development.