Use of a real-time continuous glucose monitoring system in children and young adults on insulin pump therapy: patients' and caregivers' perception of benefit.

BACKGROUND: Real-time continuous glucose monitoring systems (RT-CGMS) are a recently introduced technology for type 1 diabetes and experience in children is limited. OBJECTIVE: To assess patient and caregiver's perception of benefits and disadvantages of RT-CGMS in children or young adults with type 1 diabetes mellitus (DM) on insulin pump therapy. SUBJECTS AND METHODS: Forty-three subjects (3-25 yr) on insulin pump therapy were included in the study. Thirty-four used RT-CGMS for a short-term trial (4 wk, ST group) and nine as a long-term tool (2-18 months, LT group). Forty subjects or their caregivers completed a questionnaire. RESULTS: On the basis of the questionnaire responses, hypoglycemia prevention was the most common perceived benefit (88%), followed by elimination of hypoglycemia-related anxiety (83%), ease of pattern management (85%), improvement of diabetes control (80%), improvement of quality of life (78%), and ease of diabetes care (78%). Negative effects included irritation/annoyance from the sensor alarm (48%) and insertion site bruising, pain, or irritation (43%). A small percentage of patients who were interested in purchasing the device (12%) decided against using it LT after a 4-wk trial on RT-CGMS. CONCLUSIONS: The most common perceived benefits of RT-CGMS are prevention of hypoglycemia and decrease in hypoglycemia-related anxiety. Negative effects are uncommon and seem to be unlikely to affect the decision to use RT-CGMS for a LT. A ST trial seems to be a valuable tool for the patient/caregiver in determining whether to purchase the device and in setting realistic expectations of its potential benefits.

Treatment of pituitary gigantism with the growth hormone receptor antagonist pegvisomant.

CONTEXT: Treatment of pituitary gigantism is complex and the results are usually unsatisfactory. OBJECTIVE: The objective of the study was to describe the results of therapy of three children with pituitary gigantism by a GH receptor antagonist, pegvisomant. DESIGN: This was a descriptive case series of up to 3.5 yr duration. SETTING: The study was conducted at a university hospital. PATIENTS: Patients included three children (one female, two males) with pituitary gigantism whose GH hypersecretion was incompletely controlled by surgery, somatostatin analog, and dopamine agonist. INTERVENTION: The intervention was administration of pegvisomant. MAIN OUTCOME MEASURES: Plasma IGF-I and growth velocity were measured. RESULTS: In all three children, pegvisomant rapidly decreased plasma IGF-I concentrations. Growth velocity declined to subnormal or normal values. Statural growth fell into lower growth percentiles and acromegalic features resolved. Pituitary tumor size did not change in two children but increased in one boy despite concomitant therapy with a somatostatin analog. CONCLUSIONS: Pegvisomant may be an effective modality for the therapy of pituitary gigantism in children. Titration of the dose is necessary for optimal efficacy, and regular surveillance of tumor size is mandatory.

Augmentation of growth hormone secretion after testosterone treatment in boys with constitutional delay of growth and adolescence: evidence against an increase in hypothalamic secretion of growth hormone-releasing hormone.

The increase in pituitary GH secretion that occurs during mid-late puberty in boys follows an increase in circulating testosterone (T) concentration; the direct mechanism by which this occurs is unknown. We hypothesized that T increases GH secretion during puberty by augmenting hypothalamic output of GHRH. Using constant infusions of a GHRH antagonist, we tested this hypothesis in six early pubertal boys with constitutional delay of growth and adolescence who had a mean chronological age of 14.0 +/- 0.3 yr and mean bone age of 11.4 +/- 0.2 yr. Blood samples were obtained from subjects every 15 min for 24 h during the overnight infusion of normal saline (2000-0600 h) and again during the overnight infusion of GHRH antagonist (0.33 microg/kg/h) the following night. Subjects then received transdermal T (5-mg patch) for 12 h nightly and were studied again after 4 wk of treatment. Serum samples were assayed for GH and total ghrelin; the percent suppression of GH during GHRH antagonist infusion was calculated. Morning serum T rose from 0.44 +/- 0.09 to 4.43 +/- 0.74 microg/liter (P = 0.005). T treatment was associated with a 92.6% increase in mean nocturnal GH secretion area under the curve (830 +/- 177 to 1599 +/- 340 microg/24 h.liter). Infusion of GHRH-antagonist suppressed mean nocturnal GH area under the curve by 29.1% before T treatment (830 +/- 177 to 621 +/- 168 microg/24 h.liter), and by 29.4% after T treatment (1599 +/- 340 to 1182 +/- 249 microg/24 h.liter; P = 0.99). Somatotroph sensitivity to GHRH was tested with 0.1- and 1.0-microg/kg doses of GHRH-44 iv; GH response did not change with regard to T treatment. The mean 24-h concentration of total ghrelin was unchanged with regard to T treatment. In summary, nightly transdermal T administration in six boys with constitutional delay of growth and adolescence increased GH output almost 2-fold, whereas the degree of GH suppressibility by GHRH antagonist remained unchanged. We conclude that the T-associated augmentation of GH secretion during early puberty in boys is unlikely to involve an absolute increase in hypothalamic GHRH output.

Sex differences in FSH-regulatory peptides in pubertal age boys and girls and effects of sex steroid treatment.

BACKGROUND: FSH concentrations are higher in girls than in boys before puberty. We hypothesized that steroid-mediated changes in FSH-regulatory proteins underlie the sex differences in FSH secretion and pubertal timing. METHODS: FSH-regulatory proteins, LH, FSH and sex steroids were measured in five boys, 10 girls, and five girls with Turner syndrome before and during sex steroid treatment (girls, 0.05 mg/day estradiol; boys, 5 mg/day testosterone) for up to 4 weeks. Blood was obtained every 15 min from 20.00 to 08.00 h before and during sex steroid treatment. RESULTS: The mean FSH concentration was higher in girls than in boys (P = 0.0044). Activin-A concentrations were greater (P < 0.0001) and inhibin-B concentrations lower (P < 0.0001) in girls compared with boys. Steroid treatment (i) suppressed LH/FSH concentrations in all subjects; (ii) increased the mean activin-A concentration in all but the Turner girls (P = 0.001); and (iii) decreased inhibin-B concentrations in boys (P = 0.005) but not in girls. Total follistatin and follistatin 288 concentrations did not differ by sex. CONCLUSIONS: Sex steroids regulate circulating activin-A and inhibin-B concentrations in children. The lower inhibin-B and higher activin-A concentrations may explain the higher FSH and earlier onset of puberty in girls.

Somatostatin analogs in medical treatment of acromegaly.

Although acromegaly remains a disease primarily addressed by pituitary microsurgery, most patients require secondary treatment for persistent growth hormone (GH) hypersecretion and elevated serum insulin-like growth factor-1 (IGF-1) concentrations following adenomectomy. Persistently abnormal serum GH and IGF-1 can be reduced to normal concentrations in better than half of post-surgery acromegalics using the pharmacologic treatments available at present, the dopamine agonists (DA) and somatostatin (SST) analogs. The long-acting SST analogs octreotide LAR and lanreotide SR have become the mainstay of medical treatment for acromegaly, having largely supplanted DA agents since the introduction of bromocriptine for the suppression of GH secretion in the 1970s. The DA cabergoline may be effective in up to half of patients, however, in particular those patients whose tumors cosecrete prolactin. On the horizon is the GH-receptor antagonist pegvisomant, which is expected to enable the reduction of serum IGF-1 to the normal range in the vast majority of postoperative acromegaly patients, representing a revolutionary development in the medical treatment of this disease. We here review the choices available to the endocrinologist in the pharmacologic treatment of acromegaly, focusing upon the SST analogs.

Medical management of growth hormone-secreting pituitary adenomas.

The primary treatment of acromegaly remains transsphenoidal adenomectomy, yet the tissue overgrowth of acromegaly often progresses following surgery, and responds to radiotherapy only after significant delay. Persistently elevated serum growth hormone (GH) and insulin-like growth factor-I (IGF-I) concentrations can be normalized in about half of post-surgery acromegalics using the pharmacologic alternatives presently available, the dopamine agonists (DA) and somatostatin (SST) analogs. Cabergoline, the most efficacious DA, normalizes IGF-I in approximately 37% of patients, whereas the long-acting SST analogs, Octreotide LAR and Lanreotide SR, do so in 66%. Significant tumor shrinkage may be attained with SST analogs in particular, and when necessary, the primary medical treatment of acromegaly may be successfully addressed with this class of drugs. Greatly enhanced efficacy is expected from the GH receptor antagonist pegvisomant, which is nearing market availability and will enable the normalization of serum IGF-I in virtually all patients treated. We review here the pharmacologic treatments of excessive GH secretion.