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The ob protein, termed leptin, is produced by adipocytes and is thought to act as an afferent satiety signal regulating weight through suppressing appetite and stimulating energy expenditure in humans and/or rodents. Insulin has been found to be a potent stimulator of leptin expression in rodents. It is unclear at present whether this insulin action is a direct or an indirect effect. To investigate whether leptin concentrations in children and adolescents with type 1 diabetes (IDDM) were related to metabolic status, body weight, body mass index and insulin treatment, we have measured leptin concentrations in serum from 13 newly diagnosed IDDM patients before the beginning of insulin treatment (8 girls, 5 boys, aged 4.7-17.5 years) and in 134 patients with IDDM during treatment (64 girls, 70 boys, aged 2.6-20.1 years) using a specific radioimmunoassay. The data from patients with diabetes were compared with normative data that were derived from a large cohort of healthy children and adolescents. Serum from children with newly diagnosed diabetes had significantly lower levels of leptin (mean 1.28+/-1.60 ng/ml, range 0.14-6.13 ng/ml) compared with healthy children (n=710) (mean 2.2 ng/ml, range 0.26-14.4ng/ml) and compared with insulin-treated children and adolescents (mean 5.18+/-5.48 ng/ml, range 0.26-29.77 ng/ml) (P<0.0001) even after adjustment for gender and body mass index (BMI). Serum leptin levels in patients with IDDM were significantly correlated with BMI (r=0.42, P<0.0001). Multiple regression analysis showed that age and BMI were significantly correlated with leptin levels, while duration of diabetes, mean HbA1c levels, insulin dose and plasma glucose, triglyceride and cholesterol levels were not. Females had higher serum leptin concentrations than males even when adjusted for BMI (P<0.0001). Surprisingly and most importantly, leptin levels in insulin-treated young adult (Tanner stage 5) patients were significantly higher than values found in the healthy nondiabetic reference population when adjusted for sex, Tanner stage and BMI. These findings suggest that leptin levels in IDDM patients show a similar dependency on adipose tissue and age as in healthy, normal children. The data provide evidence that insulin may be of importance as a regulator of serum leptin levels in vivo not only in rodents but also in humans. It is hypothesized that the elevated BMI-adjusted leptin levels in adolescents with IDDM could indicate either that these patients may be oversubstituted by the intensified insulin therapy that they are receiving or that their body composition and body fat content may differ from that of healthy adolescents in the sense that they have a relative increase in fat mass.

In ob/ob mice, leptin deficiency results in hypogonadotrophic hypogonadism, impaired sexual maturation and infertility, which are all corrected by leptin administration. In humans, pubertal development and menarche are related to the attainment of a critical amount of body fat. To examine whether changes in circulating concentrations of leptin could be a hormonal signal influencing gonadotrophin secretion, we studied 98 adolescents and young adults of both sexes, aged 13-19 years, whose weight varied from normal to massively obese and whose sexual maturation was between Tanner stages 3 and 5. We measured leptin, sex steroids and circulating gonadotrophin concentrations in the basal state and in response to GnRH. In perimenarchial and young adult girls, we found that the LH and FSH responses to GnRH were negatively correlated with body mass index (BMI: r = -0.45 and -0.47 respectively, P < 0.0025) and circulating leptin (r = -0.53 and -0.49 respectively, P < 0.002). Decreased LH and FSH responses to GnRH were associated with increased adiposity and hyperleptinaemia. Our data do not establish, but are consistent with a direct neuroendocrine negative effect of excess leptin on the central reproductive system of obese girls. In boys of comparable adiposity, we found no influence of BMI or leptin on gonadotrophin concentrations, which is another aspect of the sexual dimorphism characterizing human leptin physiology.

Non-classic congenital adrenal hyperplasia (NCAH) is a relatively common disorder regardless of ethnicity, but most cases are never diagnosed, especially in males. A baseline 17-hydroxyprogesterone measurement may be used for screening, but 17-hydroxyprogesterone measurement after ACTH stimulation is the gold standard. We advocate a CYP21A2 mutation analysis to verify the diagnosis, for genetic counselling and for better prognostic and treatment guidance. Most patients are diagnosed in adolescence and adult life with hirsutism, acne, a PCOS-like picture and fertility issues. Many men with NCAH never seek medical attention and escape diagnosis. Although treatment is somewhat controversial, an early diagnosis and start of treatment may have positive implications on growth and be relevant for preventing and ameliorating the symptoms and consequences of androgen excess that develop over time, including fertility issues. Long-term treatment with glucocorticoids will improve the androgen symptoms but may result in long-term complications, such as obesity, insulin resistance, hypertension, osteoporosis and fractures. The glucocorticoid doses should be kept low. However, complications seen in NCAH, assumed to be caused by the glucocorticoid treatment, may also be associated with long-term androgen exposure. Oral contraceptive pills are a common treatment option for young females with NCAH. Regular clinical monitoring to improve the clinical outcome is recommended. It is important to acknowledge that glucocorticoid treatment will lead to secondary cortisol insufficiency and the need for stress dosing. Studies focusing on the specific difficulties patients with NCAH face, both those with a late clinical diagnosis and those with a neonatal diagnosis obtained by screening, are warranted.

Objective: Clinical features associated with microdeletion of chromosome 22q11 (del(22)(q11)) are highly variable. Increased awareness of this condition is needed among specialists such as endocrinologists to reduce diagnostic delay and improve clinical care. The purpose of this study was to describe the phenotype of patients with del(22)(q11), focusing on parathyroid gland dysfunction.

Design and methods: Charts of 19 patients, including one kindred of three, known to have del(22)(q11) diagnosed by fluorescence in situ hybridization (FISH) were reviewed from the register of the department of Medical Genetics. Major clinical features including hypoparathyroidism phenotype were collected.

Results: Parathyroid dysfunction was present in 8 out of 16 patients (50%). Six patients were diagnosed with overt hypoparathyroidism. Hypocalcemia manifested as laryngeal stridor within the first days of life (n=3), seizures in infancy (n=1) and adolescence (n=2). The connection between hypoparathyroidism and diagnosis of del(22)(q11) was belated at the median age of 18 years. One patient had presented with transient neonatal hypoparathyroidism, and one patient had latent hypoparathyroidism. Within the kindred family, the phenotype variability including that of parathyroid dysfunction was as marked as between unrelated individuals. Standard karyotype failed to detect the deletion in 15 out of 19 cases.

Conclusions: Abnormal parathyroid function in the del(22)(q11) ranges from severe neonatal hypocalcemia to latent hypoparathyroidism. Del(22)(q11) should be considered as a potential cause of hypocalcemia even in young adult. When suspected, the diagnosis requires investigation by FISH. Furthermore, long-term calcemia follow-up is needed in normocalcemic patients with del(22)(q11) because of the possible evolution to hypocalcemic hypoparathyroidism.

OBJECTIVE: A sex difference in fetal and neonatal pituitary-gonadal function has been well documented. The aim of the following study was to determine sex differences and patterns of basal LH/FSH in the neonatal period. DESIGN: Peripheral venous blood was obtained from 164 healthy full term newborns (91 males, 73 females) for clinically indicated laboratory examinations. RESULTS: In male newborns, LH values were initially low (days 1-5), increased between days 6 and 10, and reached maximum levels between days 16 and 20. Levels of FSH were initially low (days 1-5), increased between days 6 and 10 and reached maximum levels between days 11 and 15. In female newborns, LH levels were generally lower than in newborn boys; levels were initially low, then increased between days 11 and 15 and reached maximum levels at the end of the newborn period. FSH values were generally higher than in newborn boys; there were initially low values with a first peak between days 11 and 15 and a second peak between days 21 and 28. CONCLUSIONS: LH values in male newborns were higher and exceeded values in female newborns, whereas FSH values in female newborns exceeded male newborn values. Male newborns do not exhibit any peaks of LH and FSH activity, whereas female newborns exhibit two FSH peaks during this period.

OBJECTIVE: To identify the molecular defect by which psychomotor retardation is caused in two brothers with congenital hypothyroidism who received adequate treatment with l-thyroxine. CASE REPORT: A six-year-old boy presented with psychomotor retardation and congenital primary hypothyroidism (CH). The patient had a normal blood thyrotrophin (TSH) level on neonatal screening, but low total serum thyroxine and triiodothyronine concentrations prompting thyroid hormone substitution shortly after birth. Nevertheless, psychomotor development was retarded and the patient underwent further investigation. Typical features of Albright's hereditary osteodystrophy (AHO) such as round face, obesity, and shortened 1st, 4th and 5th metacarpals were found. METHODS AND RESULTS: Further investigation confirmed AHO with pseudohypoparathyroidism (PHP) type Ia. The boy had a mild resistance to parathyroid hormone and a reduced adenylyl cyclase stimulating protein (Gsalpha) activity in erythrocytes. DNA analysis detected a new heterozygous mutation (L338N) in the Gsalpha protein (GNAS1) gene. This mutation was also present in the patient's brother who had similar features and was also treated with thyroid hormone because of CH, and in the phenotypically normal-looking mother who had a normal calcium metabolism but a reduced Gsalpha protein activity in erythrocytes suggestive of pseudopseudohypoparathyroidism. CONCLUSION: In patients with CH, in whom the neurological outcome is poor even under adequate thyroid hormone substitution, PHP Ia may be suspected, especially when symptoms of AHO are present.