The Journal of pediatric endocrinology最新文献

Multiple target organ involvement in pseudohypoaldosteronism is known but partial defects involving only a single organ system have also been described. In this report we present a girl with early symptoms and a very mild course of the disease without renal salt wasting and with normal sweat osmolality. Sodium content and the sodium/potassium ratio of stool was highly elevated. Increased plasma renin activity and aldosterone concentration as well as a reduced number of aldosterone receptors in mononuclear leucocytes confirmed the diagnosis of pseudohypoaldosteronism. Partial pseudohypoaldosteronism maybe more frequent than currently diagnosed since salt loss can be compensated by intact organ systems, but nevertheless threatens the young patient during illness. Since various degrees of clinical severity of pseudohypoaldosteronism even in the same family have been described, it seems important to identify mild cases in order to monitor younger siblings.

The aim of our study was to determine whether first-phase insulin response to intravenous (i.v.) glucose could be used as a simple and rapid test to identify cystic fibrosis (CF) patients at risk to develop diabetes mellitus. Forty consecutive CF patients with normal fasting blood glucose values but with different degrees of glucose tolerance on the standard oral glucose tolerance test (22 with normal glucose tolerance, 16 with impaired glucose tolerance, 2 with diabetes mellitus) and 12 normal subjects, matched for age and body mass index, underwent an i.v. glucose bolus to evaluate early phase insulin release. When compared to the normal subjects, CF patients had significantly reduced basal (76 +/- 50 vs 108 +/- 30 pM/l, 2 p < 0.02) and glucose stimulated insulin levels (1 + 3 min insulin = 456 +/- 275 vs 951 +/- 170 pM/l, 2 p < 0.01). Early phase insulin release, however, did not differentiate between CF patients with normal and impaired glucose tolerance; also in the two diabetic patients insulin levels did not clearly differ from those observed in the other groups of CF subjects. In conclusion, first-phase insulin response may identify an impairment of B-cell function in CF subjects; however, it does not discriminate between different degrees of glucose tolerance, as determined by the oral glucose tolerance test and, therefore, it does not reliably identify those patients who will eventually develop overt diabetes mellitus.

Insulin dependent diabetes mellitus (IDMM) is often associated with autoimmune thyroiditis (AIT) and a high prevalence of thyroid antibodies (TA). Ultrasound imaging of the thyroid may contribute to the evaluation of patients with AIT. We therefore investigated ultrasound findings of the thyroid in 83 IDDM patients (44F, 39M) with an age range of 2.3-22.3 yrs (median 11.1). Thyroid volume (ml) determined by ultrasound ranged between 1.3 and 17.9 (median 5.7). Thyroid volumes of 75 healthy children (32F, 43M) with an age range of 2.0 to 11.8 yrs (median 7.6) ranged between 1.6 and 13.2 ml (median 4.8) and did not show a significant difference from the IDDM group from age 4 to 12. TA were positive in 18.8% of the IDDM group. Thyroid volume was higher in TA (+) diabetics (p = 0.05), a finding which may be attributed to a higher percentage of cases with elevated TSH in the TA (+) group. Two diabetic patients showed non-homogeneous hypoechogenicity in the ultrasound compatible with AIT which was later confirmed in one of these cases by aspiration biopsy. Ultrasound imaging of the thyroid may contribute to the evaluation of patients with AIT in IDDM.

Severe hypothyroidism in an 8 year-old girl was associated with a paradoxically high free thyroxine (T4), a high TSH level and antimicrosomal antibodies suggestive of Hashimoto's thyroiditis. Low radiolabelled T3 binding to resin in the standard T3 resin uptake test suggested thyroid hormone binding which was subsequently found to be due to antibodies to T4. T4 by equilibrium dialysis was very low confirming that conventional free T4 and total T4 assays overestimated the true values. Subsequent normalization of free T4 by dialysis coincided with a decline in the T4 autoantibody titer allowing a change in treatment from Cytomel (triiodothyronine) to Synthroid (L-thyroxine) while maintaining therapeutic efficacy.

The aim of this study was to evaluate the effects of prenatal asphyxia on perinatal thyroid function by measuring the levels of serum T4, FT4, T3, rT3, TSH and TBG in twenty-seven asphyxiated full-term infants delivered by emergency cesarean section, at birth and on the 5th day of age. All the babies had a one-minute Apgar score of less than 6 and body weight from 3 to 4.6 kg. The control group consisted of 30 healthy neonates which were delivered by elective cesarean section. The mean values of T4 and FT4 observed in the cord blood of the asphyxiated neonates were significantly lower compared to the matched controls, while there were no differences in concentrations of T3, rT3, TSH and TBG. At five days of life, serum concentrations of T4 and FT4 became normal. These results demonstrate the existence of transient hypothyroxinemia at birth in hypoxic babies delivered by emergency cesarean section.

The stimulatory effect of potassium depolarization upon somatostatin mRNA (SS mRNA) levels in primary cultures of fetal cerebrocortical cells was analyzed. Depolarizing stimuli, such as 56 mM K+ concentration for 24 hours, elicited an increase in immunoreactive somatostatin (IR-SS) release to the media and SS mRNA levels, suggesting that somatostatin secretion can be coupled to SS mRNA accumulation. These changes were inhibited by the Ca2+ channel antagonist verapamil (VPM). In contrast, Na+ channel blockade by tetrodotoxin (TTX) did not modify the 24 h potassium-induced increase in SS mRNA. These results suggest that the induction of SS mRNA expression by K+ involves the modulation of calcium ion channels.

The secretion of growth hormone (GH) is governed by the remarkably complex interaction of neural and feedback regulatory components. The net result is a striking pulsatile pattern of GH release evident in every mammalian species studied so far. Extensive experimental evidence indicates that the episodic pattern of GH release from the pituitary gland is generated by a delicate interplay between at least two hypothalamic hormones--a stimulatory GH-releasing factor (GRF) and an inhibitory hormone, somatostatin (SRIF). This paper will focus on the interrelation of GRF and SRIF, and on the modulatory influence of GH and insulin-like growth factor (IGF) feedback, in the genesis of episodic GH secretion.

Growth hormone (GH) secretion is regulated by a complex system of central and peripheral signals. Recently, a new GH-releasing hexapeptide (His-D-Trp-Ala-Trp-D-Phe-Lys-NH2) called GHRP-6 which specifically releases GH has been studied. In the present work the mechanism of action of GHRP-6 has been addressed in experimental animal models as well as in obese subjects. GHRP-6 releases GH independently of the hypothalamic factors GHRH and somatostatin and is a powerful GH releaser in obesity.