Abnormal vascular reactivity in growth hormone deficiency.

BACKGROUND: The reason why patients with growth hormone (GH) deficiency (GHD) are at increased risk for premature cardiovascular death is still unclear. Although a variety of vascular risk factors have been identified in GHD, little is known regarding vascular reactivity and its contribution to premature arteriosclerosis. METHODS AND RESULTS: We assessed vascular function in 7 childhood-onset, GH-deficient nontreated patients (age 22+/-3 years, body mass index [BMI] 25+/-1 kg/m(2)) and 10 healthy subjects (age 24+/-0.4 years, BMI 22+/-1 kg/m(2)) by using strain gauge plethysmography to measure forearm blood flow in response to vasodilatory agents. The increase in forearm blood flow to intrabrachial infusion of the endothelium-dependent vasodilator acetylcholine was significantly lower in GH-deficient nontreated patients than in control subjects (P:<0.05). Likewise, forearm release of nitrite and cGMP during acetylcholine stimulation was reduced in GH-deficient nontreated patients (P:<0.05 and P:<0.002 versus controls). The response to the endothelium-independent vasodilator sodium nitroprusside was also markedly blunted in GH-deficient patients compared with control subjects (P:<0.005). To confirm that abnormal vascular reactivity was due to GHD, we also studied 8 patients with childhood-onset GHD (age 31+/-2 years, BMI 24+/-1 kg/m(2)) who were receiving stable GH replacement therapy. In these patients, the response to both endothelium-dependent and -independent vasodilators, as well as forearm nitrite and cGMP, release was not different from that observed in normal subjects. Peak hyperemic response to 5-minute forearm ischemia was significantly reduced in GH-deficient nontreated patients (17.2+/-2.6 mL x dL(-1) x min(-1), P:<0.01) but not in GH-treated patients (24.8+/-3.3 mL x dL(-1) x min(-1)) compared with normal subjects (29.5+/-3.2 mL x dL(-1) x min(-1)). CONCLUSIONS: The data support the concept that GH plays an important role in the maintenance of a normal vascular function in humans.

Cardiac structural and functional abnormalities in adult patients with growth hormone deficiency.

Little information is available on cardiac involvement in GH-deficient adults. Thus, we evaluated cardiac structure and function by means of one- and two-dimensional echocardiography in 11 adult patients [3 women and 8 men; mean age, 27.2 +/- 3.8 (+/- SD) yr] affected with GH deficiency. Twelve age- and sex-matched normal subjects served as the control group. All patients had been treated with extractive GH over 9 yr, and therapy withdrawal had been performed at least 3 yr before entering the study. GH-deficient patients had significantly lower values of interventricular septum (7.1 +/- 1 vs. 9 +/- 0.4 mm; P < 0.01) and left ventricular posterior wall thickness (6.1 +/- 1 vs. 9 +/- 0.4 mm; P < 0.01), which resulted in a significantly smaller left ventricular mass index (54 +/- 11 vs. 85 +/- 15 g/m2; P < 0.001). The left ventricular end-diastolic and end-systolic diameters did not differ significantly after correction for body area surface, whereas ejection phase indices showed lower values, with a fractional shortening of 34 +/- 4% vs. 38 +/- 5% (P < 0.05) and an ejection fraction of 59 +/- 9% vs. 69 +/- 10% (P < 0.05). In conclusion, the results of this study demonstrate the involvement of cardiac muscle in patients affected with GH deficiency.

Acute and chronic effects of human recombinant GH (hrGH) on adrenal steroidogenesis in children affected with isolated GH deficiency (IGHD).

In a previous study we demonstrated that, in children affected with isolated GH deficiency, an acute high-dose human recombinant GH (hrGH) treatment increases the 11-deoxycortisol and induces an IGF-I responsiveness to ACTH. The aim of the present study was to reevaluate, in the same children, the adrenal and IGF-I responsiveness to ACTH after a chronic replacement-dose GH therapy. Ten children (seven males and three females, mean age 7 years) affected with isolated GH deficiency underwent a synthetic ACTH 1-17 test before and after sc administration of human recombinant GH at a dose of 0.6 UI/kg/week for 3 months. After therapy, the 11-deoxycortisol responsiveness to ACTH significantly decreased compared with that observed after acute treatment (P < 0.001), and so it returned to baseline. No differences were detected in the responsiveness to ACTH of cortisol, dehydroepiandrosterone-sulphate, D4-androstenedione, and 17-hydroxyprogesterone. On the other hand, the chronic treatment induced an IGF-I responsiveness to ACTH (P < 0.001). In conclusion, our study demonstrates that, in isolated GH deficiency, replacement doses of hrGH do not modify the adrenal steroid basal levels or its responsiveness to ACTH, whereas both replacement and high doses of hrGH induce an IGF-I responsiveness to ACTH.

Effect of a short-term treatment with recombinant growth hormone (GH) on adrenal responsiveness to corticotrophin stimulation in children affected by isolated GH deficiency.

Recent evidence suggests that GH and insulin growth factor-I (IGF-I) play a role in adrenal steroidogenesis. On the other hand, it has been shown that ACTH stimulates IGF-I secretion by cultured fasciculata adrenal cells. Aim of the present study was to investigate the influence of GH administration on adrenal steroids and IGF-I responsiveness to ACTH in children affected with isolated GH deficiency. Ten children (seven males and three females, 5-10 yr old) affected with isolated GH deficiency underwent a synthetic ACTH 1-17 test before and after administration of human recombinant GH at a dose of 4 IU/day sc for 10 days. After the therapy, no significant differences were detected in the responses of cortisol, dehydroepiandrosterone-sulfate, androstenedione, and 17-hydroxyprogesterone to ACTH 1-17, whereas an increased 11-deoxycortisol responsiveness to ACTH 1-17 was noted (P less than 0.005). Surprisingly, IGF-I significantly increased in response to ACTH 1-17 after short-term rGH administration (P less than 0.006). In conclusion, our data indicate that in isolated GH deficiency a short-term GH therapy does not substantially modify the adrenal responsiveness to exogenous ACTH, even if an increased 11-deoxycortisol and an induced IGF-I responsiveness to ACTH were observed.

Long-term and low-dose treatment with cabergoline induces macroprolactinoma shrinkage.

Cabergoline (CAB), a long-lasting dopamine-agonist, specific for the D2 receptor, is effective in normalizing serum PRL levels in most patients with microprolactinoma or idiopathic hyperprolactinemia. Because few data are presently available on the effects of CAB treatment in macroprolactinomas, the aim of this open-label study was to investigate whether this drug was effective in producing tumor shrinkage, as well as in normalizing PRL levels. Twenty-three patients with macroprolactinoma entered this study 15 patients had had no treatment, whereas the remaining 8 patients had been previously treated with bromocriptine, which was with-drawn because of intolerance. Three of 23 patients had undergone unsuccessful surgery. Pretreatment serum PRL levels ranged from 100-3860 micrograms/L. CAB was administered at a dose of 0.5-3 mg once or twice a week for 12-24 months. Magnetic resonance imaging (MRI) scans were performed before and 3, 6, 12, and 24 months after the beginning of treatment, to evaluate tumor shrinkage, defined as a decrease of at least 80% of baseline tumor volume. After 3-6 months of treatment with a low dose (0.5-1 mg/week), serum PRL levels normalized in 18 patients. In the remaining 5 patients, whose serum PRL levels were not normalized, the dose was increased to 2-3 mg/week. This schedule caused the normalization of PRL levels in 1 patient, whereas in the remaining 4 patients, PRL levels were reduced to 30-82 micrograms/L. A tumor volume reduction greater than 80% at MRI occurred in 14 of 23 patients (61%) after CAB treatment (from 2609.4 +/- 534.7 to 530.1 +/- 141.3 mm3 at the 12-24th month follow-up, P < 0.001). A volume reduction of 41.8 +/- 3.4% was already evident after 3 months (1436 +/- 285.9 mm3; P < 0.001). The complete disappearance of the tumor mass at MRI occurred after 6 months of treatment with CAB in 1 patient, and in 5 patients after 1 yr of treatment. An improvement of visual field defects was obtained in 9 of the 10 patients presenting visual impairment before CAB treatment. The drug was tolerated well by all patients. Only 1 patient experienced mild nausea, which disappeared spontaneously after the 2nd day of treatment. Long-term, a low dose of the D2 receptor agonist CAB significantly reduced tumor volume and normalized serum PRL levels in a great majority of patients bearing macroprolactinoma. This treatment met with excellent patient compliance. This study suggests that CAB can be used as a first choice drug treatment in macroprolactinomas, as already shown for microprolactinomas and idiopathic hyperprolactinemia.

Prolactinomas resistant to standard dopamine agonists respond to chronic cabergoline treatment.

Cabergoline (CAB), a new, potent, and long-lasting PRL-lowering agent, was shown to be effective in tumoral hyperprolactinemia. The aim of this study was to investigate the effectiveness of CAB in patients with prolactinoma proven to be resistant to bromocriptine (BRC) and quinagolide (CV 205-502). Twenty-seven patients (19 macro- and 8 microprolactinomas) were treated with CAB at a weekly dose of 0.5-3 mg for 3-22 months. All patients were previously shown to be resistant to BRC, and 20 of them were resistant to CV 205-502 as well. Basal serum PRL levels before CAB treatment ranged from 108-3500 micrograms/L in macroprolactinomas and from 64-205 micrograms/L in microprolactinomas. Gonadal failure was present in all patients, whereas symptoms of tumor expansion, such as visual field defects and headache, were present in 10 of 27 patients. Eight macroprolactinomas had previously undergone surgery and/or radiotherapy. CAB treatment normalized serum PRL levels in 15 of 19 macroprolactinomas and in all 8 microprolactinomas. In 3 of the remaining 4 patients it caused a notable decrease in prolactinemia (89%, 80.5%, and 68.7% of the baseline). Only 1 patient was withdrawn from CAB therapy after 3 months at the weekly dose of 2 mg due to the absence of any significant clinical, hormonal, or radiological improvement. Gonadal function was restored in 18 of 27 patients, galactorrhea disappeared in 5 of 6 women, and headache improved in 7 of 8 patients. A significant tumor shrinkage was detected by computed tomography and/or magnetic resonance imaging in 9 macroprolactinomas and 4 microprolactinomas. CAB was well tolerated by all patients, except 6 who referred slight and short-lasting nausea, postural hypotension, abdominal pain, dizziness, and sleepiness at the beginning of treatment. In particular, CAB was well tolerated by 19 patients previously shown to be poorly tolerant to BRC and CV 205-502. In conclusion, CAB may represent, at the moment, the only successful therapy for prolactinoma-bearing patients resistant to BRC and CV 205-502, as it normalized PRL levels in 22 of 27 patients, reduced tumor size in 13 of 27 patients, and improved clinical symptoms in 25 of 27 patients in the present study.

The effect of hexarelin on growth hormone (GH) secretion in patients with GH deficiency.

Hexarelin (Hex) is a new synthetic hexapeptide with potent GH-releasing activity in both animals and men. We evaluated the GH response to maximal doses of Hex (2 micrograms/kg, iv) and GHRH-(1-29) (1 microgram/kg, iv) in 15 children (11 boys and 4 girls, aged 6.0-17.3 yr) and 4 adults (3 men and 1 woman, aged 20.2-30 yr) with GH deficiency (GHD). GHD was idiopathic in 8 patients and associated with pituitary stalk interruption syndrome in 8, with a pituitary cyst in 2, and with empty sella syndrome in 1. In 11 patients, GHD was isolated, whereas in 8, it was associated with other pituitary hormone deficiencies. Forty-five short normal children (24 boys and 21 girls, aged 5.9-14 yr) served as controls. In patients with idiopathic GHD, the GH response to Hex was similar to that observed in short normal children, and it was significantly higher than the response to GHRH. In the patients with GHD associated with anatomical abnormalities, the GH responses to GHRH varied from normal to absent. Among these subjects, only 1 patient with a pituitary cyst had a sizable GH response to Hex, whereas in all others, the GH response to Hex was absent or blunted compared with those in the short normal children and the patients with idiopathic GHD. In all patients except those with associated ACTH deficiency, Hex administration caused a slight, but significant, increase in cortisol concentrations. This study shows that Hex stimulates GH secretion in patients with idiopathic GHD. The inability of Hex to stimulate GH secretion in patients with hypothalamic-pituitary disconnection strongly supports the concept that in humans, the GH-releasing effect of GH-releasing peptides is mediated by the hypothalamus.

Prediction of efficacy of octreotide therapy in patients with acromegaly.

Octreotide (OCT) administration provides a biochemical cure in most acromegalic patients. This drug, however, causes several side effects and is very expensive. Acute testing has been reported to predict chronic responsiveness to OCT administration. The aim of this retrospective study was to evaluate which test, if any, among acute testing, short-term (1 month) administration, and 111In-pentetreotide (111In-DTPA-Phe-D-OCT) scintigraphy, is best in predicting response to long-term OCT treatment. Sixty-eight patients with active acromegaly were studied. An acute test (100 micrograms sc OCT) was performed as usual: a GH decrease greater than or equal to 50% of baseline was considered a positive response. GH and insulin-like growth factor I (IGF-I) were then assayed after 1 month (300 micrograms daily) and 3 months (150-600 micrograms daily) of OCT administration. GH was considered normalized when decreased less than or equal to 5 micrograms/L. Twenty-six of 68 patients were subjected to 111In-pentetreotide scintigraphy. Linear correlation analysis of the results was performed. Sensitivity, specificity, and positive and negative predictive values of the three tests were also calculated. Thirty-eight of 68 patients (56%) responded to the acute test. Among these 38 patients, 20 experienced normalization of GH and IGF-I levels during long-term therapy, as did 8 patients who did not respond to the acute test. No significant correlation was found between GH percent decrease during acute testing and long-term therapy (r = 0.11). Seven patients who responded to the acute test and 2 who did not respond had adenoma shrinkage during therapy. Conversely, GH and IGF-I decrease after short-term treatment significantly correlated with long-term treatment (r = 0.76 and 0.64, P < 0.01). Of the 26 patients subjected to 111In-pentetreotide scintigraphy, 13 had significant tracer uptake: normalization of GH and IGF-I was obtained in 8 patients. A significant correlation was found between tracer uptake and GH/IGF-I inhibition after 3 months of therapy (r = 0.6; P < 0.05). In the whole population, the positive predictive value of acute testing, short-term OCT administration, and 111In-penetreotide scintigraphy was 53%, 70%, and 73%, respectively, when the GH normalization (< 5 micrograms/L) after 3 months of therapy was considered. Moreover, 111-In-pentetreotide scintigraphy had the highest specificity (100% in patients with baseline GH values below 50 micrograms/L) compared with that of acute testing and short-term OCT administration. The acute test cannot be considered as a valuable index to identify patients' responsiveness to long-term OCT therapy, but it can be useful to test tolerability. By contrast, 1 month of OCT administration or the in vivo imaging of somatostatin receptors by 111-In-pentetreotide might better indicate the patients who might effectively benefit from this treatment.

Effect of different dopaminergic agents in the treatment of acromegaly.

Medical treatment of acromegaly with dopamine agonists possesses 2 main advantages: the oral administration and the low costs. In this study, we reported on the results of chronic treatments with quinagolide (CV 205-502), cabergoline (CAB) and long-acting depot preparation of bromocriptine (BRC-LAR) in 34 acromegalics. Patients were divided into three groups on the basis of different treatment: CV 205-502 given to 16 patients at the dose of 0.3-0.6 mg/day for 6 months; CAB given to 11 patients at the dose of 1.0-2.0 mg weekly for 6 months; and BRC-LAR injected into 7 patients at the dose of 100 mg/month for 6-12 months. Basal and oral glucose tolerance test-stimulated serum GH levels, basal and TRH-stimulated PRL levels, plasma insulin-like growth factor I (IGF-I) levels, computed tomography scan, and/or magnetic resonance imaging were assessed before and quarterly during treatments. The chronic administration of CV 205-502, CAB, and BRC-LAR caused a significant decrease of circulating GH, IGF-I, and PRL levels (P < 0.005). Normalization of circulating GH and IGF-I levels was obtained in 7 of 16 (43.8%) patients treated with CV 205-502. Serum GH response to oral glucose tolerance test (oGTT) significantly improved (P < 0.005), and PRL levels were significantly suppressed during treatments. No correlation was found between basal and TRH-stimulated PRL levels and GH suppression during different therapies. Immunohistochemical staining revealed 19 GH-positive and 10 GH + PRL-positive adenomas. A significant association was found between GH/PRL staining and responsiveness to chronic treatments (chi 2 = 7.985, P < 0.005). Three patients had significant adenoma shrinkage. Slight nausea and hypotension which spontaneously disappeared within therapy progression, were referred by 5/16 patients during CV 205-502 and 2/7 during BRC-LAR. The results of this study indicate that CAB and BRC-LAR cannot be considered as useful medical approaches for acromegalics, whereas CV 205-502 normalized circulating GH and IGF-I levels in 47.8% of patients.

Impaired cardiac performance is a distinct feature of uncomplicated acromegaly.

This study was designed to assess right and left ventricular function in patients with active acromegaly. To this end, 26 acromegalic patients (9 of whom had arterial hypertension) and 15 normal subjects of comparable age and sex distribution were studied by radionuclide angiography at rest and during supine bicycle-ergometer exercise and echocardiography. At rest, the filling rates of left (-19%; P < 0.005) and right ventricle (-32%; P < 0.001) were significantly reduced in acromegalic patients, whereas right and left ventricle ejection fractions (EFs) were normal. During physical exercise, EF was considerably lower in the acromegalic patients than in controls. This was true for both left (61 +/- 11% vs. 75 +/- 8%; P < 0.001) and right ventricle (45 +/- 13 vs. 58 +/- 11%; P < 0.002). In as many as 73% of patients, EF increased less than 5%, thus fulfilling the criteria for impaired cardiac performance. Left ventricular mass index was 60% greater in acromegalics than in controls (P < 0.001). A significant difference in left ventricular mass index was also present when normotensive acromegalic patients were compared with controls (P < 0.001). No significant difference in the indices of systolic and diastolic function was observed between the subgroups of normotensive and hypertensive acromegalics, either at rest or during exercise. The data demonstrate that in uncomplicated acromegaly, besides cardiac hypertrophy, there are also important alterations of systolic and diastolic function of both ventricles, leading to a significant impairment of cardiac performance.