Effect of rosiglitazone on serum IGF-I concentrations in uncontrolled acromegalic patients under conventional medical therapy: results from a pilot phase 2 study.

OBJECTIVE: Current therapies for acromegaly are unsatisfactory for some patients. High-dose thiazolidinediones have been reported to reduce serum GH levels in animal models of acromegaly. The objective of the study was to evaluate the effect of increasing doses of rosiglitazone on serum GH and IGF-I concentrations in acromegalic patients. DESIGN: Phase 2 clinical trial. PATIENTS AND METHODS: Five consecutive patients with active and uncontrolled acromegaly under conventional medical therapies were treated with increasing doses of rosiglitazone [4 mg/day every month, starting from 8 up to 20 mg/day] added to previous medical therapies for acromegaly. RESULTS: Mean serum IGF-I concentrations decreased from 547 ± 91 to 265 ± 126 µg/l (p<0,001) during rosiglitazone treatment: 4 patients had normal serum IGF-I concentrations, and a patient had lowered serum IGF-I values, although still abnormal, at the end of the study. On the contrary, serum GH concentrations did not significantly changed during rosiglitazone therapy as well as other pituitary hormones. No relevant side effects of rosiglitazone were observed during the study period. Quantitative real time PCR and Western blotting showed that rosiglitazone lowered GH-dependent hepatic generation of IGF-I in HepG2 cell line. CONCLUSIONS: Rosiglitazone reduces serum IGF-I concentrations in patients with uncontrolled acromegaly under conventional medical therapies, likely acting on the GH-dependent hepatic synthesis of IGF-I. Large studies are necessary to confirm the role of rosiglitazone as an adjunctive therapy for uncontrolled acromegalic patients under conventional medical therapies.

Effects of somatostatin analogues on acromegalic cardiomyopathy: results from a prospective study using cardiac magnetic resonance.

OBJECTIVE: Left ventricular (LV) hypertrophy is the main finding of patients with active acromegaly at cardiac magnetic resonance (CMR). The aim of the study was to evaluate heart changes in acromegalic patients treated with somatostatin analogues (SMSA) using CMR. DESIGN AND PATIENTS: This was a prospective study. Fourteen consecutive patients (8 women, mean age 46+/-10 yr) with untreated active acromegaly were submitted to CMR and 2D-color Doppler echocardiography before and after a 6-month SMSA course. MEASUREMENTS: LV volume, mass (LVM) and wall thickness. RESULTS: CMR: Mean LVM and LVM index (i) decreased from 151+/-17 g and 77+/-9 g/m2, to 144+/-24 g and 70+/-12 g/m2, respectively (p=0.047 and p<0.0001, respectively); LV hypertrophy reverted in 6 out of 10 patients (p=0.016). Systolic function, evaluated by measuring LV ejection fraction remained normal in all patients (67+/-11%). There was not a correlation between changes in LVMi and changes in serum IGF-I concentrations. However, patients with controlled disease had higher reduction of LVMi than those with uncontrolled acromegaly (DeltaLVMi, -8.2+/-4.2 vs 4.0+/-5.3 p<0.05). 2D-echo cardiography: Mean LVMi decreased from 110+/-24 g/m2 to 100+/-20 g/m2 (p=0.026); hypertrophy, revealed in 5 patients (36%) at baseline, reversed in 2 patients (p=0.500) after SMSA; abnormal diastolic function [evaluated by isovolumic relaxation time or early (E) to late of atrial (A) peak velocities ratio] found in 4 patients (29%) at the study entry, improved in a patient. Systolic function remained within the normal range in all patients during the study period. CONCLUSIONS: CMR detects changes in LVMi in most patients with acromegaly treated with SMSA, which are more evident if the disease is controlled.

Short- and long-term changes of quality of life in patients with acromegaly: results from a prospective study.

Quality of life (QoL) may be affected in acromegalic patients, although the role of disease activity is still unsettled. The aim of the study was to assess the QoL of acromegalic patients with a specific questionnaire (ACROQOL). ACROQOL was evaluated in a prospective study (at baseline, at 6 and 24 months) in 23 active untreated acromegalic patients. Control of acromegaly was defined by normal age-matched serum IGF-I concentrations. Patient groups were defined as controlled or uncontrolled at 6 months and at 24 months: controlled or uncontrolled during the entire study period (ACRO(CC) or ACRO(NC), respectively) or uncontrolled at 6 months and controlled thereafter (ACRO(C)). At 6 months, ACROQOL scores improved globally (from 54.3+/-21 to 65.1+/-19, p=0.04) as did subdomains and were inversely related to IGF-I variation (r=-0.50, p=0.052). At 24 months, ACROQOL improved globally (from 54.3+/-21 to 65.7+/-18.0, p=0.04) and this was also seen in the appearance subdomains; however, no correlation was revealed between variation of serum IGF-I concentrations and changes in ACROQOL total score (r=0.008, p=0.87). ACROQOL scores did not significantly change in ACRO(NC) (p=0.310) and in ACRO(C) (p=0.583), whereas it improved globally (from 42.1+/-22.1 to 58.8+/-16.04, p=0.021) and in psychological subdomains in ACRO(CC); however, it reflected the improvement occurred within the first 6 months of disease control. In conclusion, successful treatment, which normalizes disease activity, improves QoL in acromegaly in the short term. However, the lack of correlation between the ACROQOL score in the long term might suggest that factors other than serum IGF-I participate in the well-being of acromegalic patients; however, due to the small sample size, our results need to be confirmed in larger studies.

Potassium perchlorate only temporarily restores euthyroidism in patients with amiodarone-induced hypothyroidism who continue amiodarone therapy.

CONTEXT: Amiodarone-induced hypothyroidism (AIH) may occur in patients with or without underlying thyroid disorders. In the latter, restoration of euthyroidism, after amiodarone discontinuation, can be facilitated and accelerated by a short course of potassium perchlorate (KClO4). However, it is unknown whether KClO4 may exert similar effects on thyroid function of AIH patients if amiodarone treatment is continued. OBJECTIVE: To evaluate the effects of KClO4 on thyroid function in AIH patients (without underlying thyroid disease) while continuing amiodarone treatment. DESIGN AND PATIENTS: An open, prospective study of 10 consecutive AIH patients without underlying thyroid abnormalities referred to a tertiary referral center, and treated with KClO4 (600 mg/day) for a period of 26+/-13 days (range, 15-45 days). An additional, historical group of 12 consecutive patients with subclinical AIH left untreated while continuing or after withdrawing amiodarone was retrospectively evaluated as to the outcome of thyroid function. MEASUREMENT: Serum free T4, free T3, and TSH concentrations were measured at booking, during KClO4 treatment and after withdrawing the drug. RESULTS: In the prospective study, KClO4 treatment restored euthyroidism in all patients within 28+/-11 days (range, 15-45 days). After KClO4 withdrawal, however, all patients became hypothyroid again after 45+/-15 days (range, 30-60 days). Two patients developed mild leukopenia (1 case) or a slight increase in serum creatinine levels (1 case), which promptly normalized after KClO4 withdrawal. In the historical group, followed for at least 12 months, euthyroidism was spontaneously and stably achieved after an average of 6 months in 5 patients in whom amiodarone could be discontinued, while subclinical hypothyroidism persisted in 7 patients in whom amiodarone had to be continued. CONCLUSIONS: KClO4 very effectively restores normal thyroid function in AIH patients without underlying thyroid abnormalities, despite the fact that amiodarone therapy is continued. However, euthyroidism does not persist after KClO4 is withdrawn; in addition, spontaneous recovery of euthyroidism does not seem to occur in this subset of AIH patients, unless amiodarone is discontinued. Therefore, also in view of its potential side-effects, KClO4 cannot be recommended as a first-line treatment for AIH if amiodarone needs to be continued, while LT4 replacement is recommended under these circumstances, with periodical reassessment of thyroid function.

Long-term outcome of thyroid function after amiodarone-induced thyrotoxicosis, as compared to subacute thyroiditis.

BACKGROUND: Two main forms of amiodarone- induced thyrotoxicosis (AIT) exist: type 1 AIT is a condition of true hyperthyroidism developing in patients with pre-existing thyroid disorders, and usually requires thyroid ablative treatment. On the other hand, type 2 AIT is a form of destructive thyroiditis occurring in normal thyroids, the management of which usually consists in glucocorticoid treatment. AIM: To assess the long-term outcome of thyroid function in a prospective study of type 2 AIT patients, as compared to patients with De Quervain's subacute thyroiditis (SAT). PATIENTS AND METHODS: Sixty consecutive patients with type 2 AIT were evaluated during oral glucocorticoid treatment (oral prednisone 30 mg/day, gradually tapered and withdrawn over a 3-month period) and followed for 38+/-4 months (range 6-72) thereafter. Sixty consecutive patients with SAT, referred to our Institutes during the same period and treated with the same therapeutic schedule, served as controls. RESULTS: Type 2 AIT patients were older (p<0.0001) and showed a larger male preponderance (M:F 3.6:1 vs 0.5:1, p<0.0001) than SAT patients. Mean serum free T4 (FT4) and free T3 (FT3) concentrations at diagnosis were increased in both conditions, but higher in type 2 AIT than in SAT (FT4 47.6+/-18.8 and 29.6+/-8.3 pmol/l, respectively, p<0.0001; FT3 15.4+/-7.0 and 11.2+/-3.0 pmol/l, respectively, p<0.001). Correction of thyrotoxicosis was obtained in all patients in both groups, but restoration of euthyroidism occurred earlier in SAT than in type 2 AIT (p=0.006). Ten type 2 AIT patients (17%) and 3 SAT patients (5%, p<0.03) became permanently hypothyroid after glucocorticoid withdrawal and required levothyroxine replacement. CONCLUSIONS: A relevant proportion of type 2 AIT patients develop permanent hypothyroidism after correction of thyrotoxicosis. Thus, periodic surveillance of thyroid status is required after type 2 AIT.

Myocardial systolic strain abnormalities in patients with acromegaly: a prospective color Doppler imaging study.

BACKGROUND: Heart abnormalities are frequent findings in patients with acromegaly: systolic abnormalities are considered to be secondary to diastolic changes. AIM: The aim of the study was to evaluate whether early systolic abnormalities might be revealed in acromegalic patients using the high sensitive color Doppler myocardial imaging (CDMI) technique. PATIENTS AND METHODS: Twenty-two consecutive acromegalic patients with active untreated disease (ACROUNTR) were evaluated at baseline and after a 6-month course with SS analogs (SSa) (ACROSSa); 25 healthy subjects served as controls. All subjects underwent conventional 2D-color Doppler echocardiography, pulse wave tissue Doppler imaging (PW-TDI) and CDMI. RESULTS: Mean left ventricular (LV) ejection fraction did not differ in ACROUNTR and in controls; at variance, ACROUNTR patients had reduced mean LV diastolic function (E/A ratio: 0.96+/-0.3 vs controls: 1.6+/-0.3; p<0.002). Impairment of global LV diastolic function was confirmed by PW-TDI in ACROUNTR patients having a normal systolic function. Regional myocardial systolic strain (epsilon) and strain rate (SR) values, indices of regional systolic heart deformation, were lower in ACROUNTR [epsilonsys (S) -19.8+/-2.9 and epsilonsys (L): -17.7+/-2.2] than in controls [epsilonsys (S): -27.9+/-3.8; p<0.001 and epsilonsys (L): -25.3+/-2.6; p<0.001]. In addition, the early phase of diastolic function, evaluated using SR parameters, was impaired in acromegalic patients (p<0.005 vs controls). Strain and SR values were related to serum GH and IGF-I levels (p<0.02) and greatly improved after a 6-month course with SSa [epsilonsys (S) improved to -23.8+/-3.8 (p<0.05) and epsilonsys (L) improved to -24.7+/-2.4 (p<0.03)]. CONCLUSIONS: Our study confirms that ACROUNTR patients have impaired diastolic function. More important, our study clearly shows that ACROUNTR patients have an impairment of regional myocardial systolic function, which is not secondary to diastolic changes. These intramyocardial functional abnormalities improved during medical treatment of acromegaly. It is conceivable that GH-IGF-I excess has detrimental effects either on the diastolic or the systolic phases of heart function.

Uptake of amiodarone by thyroidal and non-thyroidal cell lines.

Amiodarone perturbs thyroid function, causing overt hypothyroidism or hyperthyroidism in 15% of patients. Changes in thyroid function are likely due, at least in part, to amiodarone and/or desethylamiodarone (DEA) concentration into the thyroid gland, but mechanisms whereby the drug uptake occurred are not known. Thyroidal (FRTL-5) or non-thyroidal [Chinese hamster ovary wild-type (CHOwt) or CHO stably transfected with NIS (CHO-NIS)] cells were exposed to 10 microM amiodarone or DEA. Cellular content of both drugs was measured by HPLC and normalized by protein concentration. Cellular concentration of the two drugs was higher in FRTL-5 (mean +/- SD 17.2 +/- 1.2 microg/mg protein of amiodarone and 18.9 +/- 0.7 microg/mg protein of DEA) than in CHO-NIS and CHOwt cells (10.8 +/- 0.8 microg/mg protein and 12.8 +/- 0.2 microg/mg protein, respectively, of amiodarone (p < 0.004); 11.9 +/- 0.1 microg/mg protein and 11 +/- 0.2 microg/mg protein, respectively, of DEA (p < 0.0002). DEA concentration was higher than that of amiodarone in all cell lines (p < 0.002). Differences between FRTL-5 and CHO cell lines were not dependent on TSH: in fact, cellular content of either drug did not change in the presence or absence of TSH in the culture medium. NIS did not intervene in amiodarone or DEA entry into thyroid cells, since amiodarone and DEA content was the same in CHOwt and CHO-NIS cells; in addition, KClO4 inhibited NIS function, but had no effect on drug uptake by the cells. At variance, 80 microM DEA reduced 125I uptake by CHO-NIS cells by 40% at 30 min without affecting cell viability. In conclusion, mechanisms whereby amiodarone is taken up by thyroid cells remain largely unknown, but the two main factors involved in thyroid-specific cellular transport, ie, NIS and TSH, seem to be excluded.

Acromegaly: effects on bone metabolism and mass.

GH has a pivotal role in maintaining bone mass and metabolism both during childhood and in adult life. This effect depends on a complex interaction between circulating and peripherically produced GH and IGF-I. In vitro data and the use of genetically modified animals have greatly expanded the understanding of regulatory mechanisms underlying the well known skeletal changes featuring acromegalic disease. The present review focuses on the effects of GH excess on bone metabolism and mass in acromegalic patients with particular attention to the influence on bone metabolism as well as arthropathy of factors such as concomitant hypogonadism, gender, age of patients and therapy.

Peroxisome proliferator-activated receptor (PPAR)gamma is highly expressed in normal human pituitary gland.

OBJECTIVE: Expression of peroxisome proliferator-activated receptor (PPAR)gamma in normal pituitary seems to be restricted to ACTH-secreting cells. The aim of the study was to evaluate the expression of PPARgamma in normal human pituitary tissue and to study its localization in the pituitary secreting cells. MATERIALS AND METHODS: Normal pituitary tissue samples were obtained form 11 patients with non-secreting adenoma who underwent surgical excision of the tumor. Expression of PPARgamma was evaluated by immunostaining and western blotting; localization of PPARgamma in each pituitary secreting cell lineage was evaluated by double immunofluorescence using confocal microscopy. Pituitary non-functioning adenomas served as Controls. RESULTS: PPARgamma was highly expressed in all pituitary samples with a (mean +/- SD) 81 +/- 6.5% of stained cells; expression of PPARgamma was confirmed by western blotting. Non-functioning pituitary adenomas had 74 +/- 11% PPARgamma positive cells. Expression of PPARy was either in cytoplasm or nuclei. In addition, treatment of GH3 cells, with a PPARgamma ligand was associated with traslocation of the receptor from cytoplasm into the nucleus. Double immunostaining revealed that every pituitary secreting cell (GH, TSH, LH, FSH, PRL and ACTH) had PPARgamma expressed. DISCUSSION: The present study demonstrated that PPARgamma is highly expressed in every normal pituitary secreting cell lineage. It can translocate into the nucleus by ligand binding; however, its role in pituitary hormone regulation remains to be elucidated.

Thyroid color flow doppler sonography and radioiodine uptake in 55 consecutive patients with amiodarone-induced thyrotoxicosis.

Amiodarone-induced thyrotoxicosis (AMT) is a life-threatening condition, the appropriate management of which is achieved by identifying its different subtypes. Type 1 AIT develops in patients with underlying thyroid abnormalities and is believed to be due to increased thyroid hormone synthesis and release; Type 2 AIT occurs in patients with a normal thyroid gland and is an amiodarone-induced destructive process of the thyroid. Management differs in the two forms of AIT, since Type 1 usually responds to combined thionamides and potassium perchlorate therapy, while Type 2 is generally responsive to glucocorticoids. Mixed forms, characterized by coexistence of excess thyroid hormone synthesis and destructive phenomena, may require a combination of the two therapeutic regimens. In this cross-sectional prospective study, 55 consecutive untreated patients, whose AIT was subtyped according to clinical and biochemical criteria, were evaluated to assess the specificity of color flow doppler sonography (CFDS) and thyroidal radioiodine uptake (RAIU) in the differential diagnosis of AIT. Sixteen patients (6 men, 10 women, age 66+/-13 yr), who had diffuse or nodular goiter with or without circulating thyroid autoantibodies, were classified as Type 1 AIT; 39 patients (27 men, 12 women, age 65+/-13 yr) with apparently normal thyroids were classified as Type 2 AIT. All Type 1 patients had normal or increased thyroidal vascularity on CFDS, while Type 2 AIT patients had absent vascularity (p<0.0001). Thirteen Type 1 AIT patients had inappropriately normal or elevated thyroidal 3-h and 24-h RAIU values (range 6-37% and 10-58%, respectively), in spite of elevated values of urinary iodine excretion; the remaining 3 patients (two with nodular goiter, one with a thyroid adenoma) had low 3-h and 24-h RAIU values (range 1.1-3.0% and 0.9-4.0%, respectively). The latter patients, who were unresponsive to the combination of methimazole and potassium perchlorate, became euthyroid after the addition of glucocorticoids. Thirty-eight Type 2 AIT patients had low 3-h and 24-h RAIU values (range 0.4-3.7% and 0.2-3.0%, respectively), but one had inappropriately normal 3-h and 24-h RAIU values (6% and 13%, respectively). In conclusion, CFDS can accurately distinguish between Type 1 and Type 2 AIT, and in general the CFDS pattern is concordant with the thyroid RAIU. However, in 4 out of 55 patients (7%) the thyroid RAIU was discrepant, probably reflecting the coexistence of Type 1 and Type 2 AIT. Thus, assessment of both CFDS and RAIU may provide a more accurate subtyping of AIT and help in selecting the appropriate therapy. Finally, in long standing iodine sufficient areas, such as the United States, where the thyroid RAIU is consistently low irrespective of the etiology of the AIT, CFDS offers a rapid and available method to differentiate between Type 1 and Type 2 AIT.

Colonic polyps of acromegalic patients are not associated with mutations of the peroxisome proliferator activated receptor gamma gene.

Peroxisome proliferator activated receptor (PPAR)gamma plays a pivotal role in regulating adipocyte differentiation and metabolism, but also has an antiproliferative effect in several tissues, including colonic mucosa, where it is highly expressed. Loss-of-function mutations have been reported in about 10% of sporadic primary colon cancer. Acromegalic patients have an increased prevalence of colonic neoplasms and lower PPARgamma levels in the colonic mucosa. Thus, PPARgamma may act as a tumor suppressor gene, and its reduced expression or loss-of-function mutations may contribute to tumorigenesis. In this study the expression and mutations of the PPARgamma gene in the colonic polyps and mucosa outside polyps were investigated in 10 acromegalic and 17 non-acromegalic patients. PPARgamma expression was evaluated by RT-PCR. PPARgamma was expressed in each sample, but expression appeared to be lower in polyps than in mucosa outside polyps from either acromegalic or non-acromegalic patients. All exons of the PPARgamma gene were directly sequenced after PCR amplification: no mutations were found either in acromegalic or in non-acromegalic patients. In conclusion, the results of this preliminary study suggest that the lower expression of PPARgamma rather than somatic mutations of this gene is involved in colonic tumorigenesis.

Iopanoic acid rapidly controls type I amiodarone-induced thyrotoxicosis prior to thyroidectomy.

Amiodarone-induced thyrotoxicosis (AIT) may develop either in apparently normal thyroid glands (Type II AIT) or in the presence of sub-clinical thyroid abnormalities (either autonomous goiter or latent Graves' disease; Type I AIT). Mixed forms also occur. While Type I AIT is due to iodine-induced excess thyroid hormone synthesis, Type II AIT is a form of amiodarone (possibly iodine) -induced destructive thyroiditis. Type I AIT is usually treated by combined thionamide and potassium perchlorate therapy, but may be resistant to therapy. On the other hand, Type II AIT often responds favorably to glucocorticoids and may not require further therapy once euthyroidism has been restored. Not infrequently, however, AIT (especially Type I) is resistant to conventional treatment, and several weeks or months may elapse before euthyroidism is restored. Thyroidectomy has been carried out in Type I AIT patients, but thyroid surgery in thyrotoxic patients, especially those with underlying cardiac problems, carries a high surgical risk. In this study we describe 3 patients with Type I AIT, who were successfully treated with a short course of iopanoic acid (IOP), an oral cholecystographic agent, which is rich in iodine and is a potent inhibitor of 5'-deiodinase, resulting in a marked decrease in the peripheral tissue conversion of T4 to T3, in preparation for thyroid surgery. Euthyroidism was rapidly restored in 7-12 days, allowing a subsequent safe and uneventful thyroidectomy in all cases. These patients were then treated with L-T4 for their hypothyroidism and amiodarone was safely re-instituted. We suggest that IOP is the drug of choice in the rapid restoration of euthyroidism prior to definitive thyroidectomy in patients with drug resistant Type I AIT.

Desethylamiodarone antagonizes the effect of thyroid hormone at the molecular level.

OBJECTIVE: To evaluate the molecular mechanisms of the inhibitory effects of amiodarone and its active metabolite, desethylamiodarone (DEA) on thyroid hormone action. MATERIALS AND METHODS: The reporter construct ME-TRE-TK-CAT or TSHbeta-TRE-TK-CAT, containing the nucleotide sequence of the thyroid hormone response element (TRE) of either malic enzyme (ME) or TSHbeta genes, thymidine kinase (TK) and chloramphenicol acetyltransferase (CAT) was transiently transfected with RSV-TRbeta into NIH3T3 cells. Gel mobility shift assay (EMSA) was performed using labelled synthetic oligonucleotides containing the ME-TRE and in vitro translated thyroid hormone receptor (TR)beta. RESULTS: Addition of 1 micromol/l T4 or T3 to the culture medium increased the basal level of ME-TRE-TK-CAT by 4.5- and 12.5-fold respectively. Amiodarone or DEA (1 micromol/l) increased CAT activity by 1.4- and 3.4-fold respectively. Combination of DEA with T4 or T3 increased CAT activity by 9.4- and 18.9-fold respectively. These data suggested that DEA, but not amiodarone, had a synergistic effect with thyroid hormone on ME-TRE, rather than the postulated inhibitory action; we supposed that this was due to overexpression of the transfected TR into the cells. When the amount of RSV-TRbeta was reduced until it was present in a limited amount, allowing competition between thyroid hormone and the drug, addition of 1 micromol/l DEA decreased the T3-dependent expression of the reporter gene by 50%. The inhibitory effect of DEA was partially due to a reduced binding of TR to ME-TRE, as assessed by EMSA. DEA activated the TR-dependent down-regulation by the negative TSH-TRE, although at low level (35% of the down-regulation produced by T3), whereas amiodarone was ineffective. Addition of 1 micromol/l DEA to T3-containing medium reduced the T3-TR-mediated down-regulation of TSH-TRE to 55%. CONCLUSIONS: Our results demonstrate that DEA, but not amiodarone, exerts a direct, although weak, effect on genes that are regulated by thyroid hormone. High concentrations of DEA antagonize the action of T3 at the molecular level, interacting with TR and reducing its binding to TREs. This effect may contribute to the hypothyroid-like effect observed in peripheral tissues of patients receiving amiodarone treatment.

A novel mutation in the pendrin gene associated with Pendred's syndrome.

OBJECTIVE: Pendred's syndrome is an autosomal recessive disorder characterized by goitre, sensorineural deafness and iodide organification defect. It is one of the most frequent causes of congenital deafness, accounting for about 10% of hereditary hearing loss. It is caused by mutations in the pendrin (PDS) gene, a 21 exon gene located on chromosome 7. The aim of this study was to examine an Italian family affected with Pendred's syndrome at the molecular level. PATIENTS: Thirteen subjects belonging to a family from Southern Italy were evaluated for the clinical and genetic features of Pendred's syndrome. MEASUREMENTS: Exons 2-21 of the PDS gene were amplified from peripheral leucocytes by the polymerase chain reaction; mutation analysis was performed by single strand conformation polymorphism, direct sequencing and restriction analysis. RESULTS: The index patient had the classical triad of the syndrome and harboured two mutations in the PDS gene in the form of compound heterozygosity. He was found to be heterozygous for a cytosine to adenosine mutation at nucleotide 1523 in exon 13 and for a IVS 1001 + 1G --> A mutation. The former is a novel mutation which results in a change of 508 threonine to asparagine in the putative eleventh transmembrane domain. The latter mutation in the donor splice site has already been described in other patients and is thought to lead to aberrant splicing and premature protein truncation. Three subjects who were heterozygous for one mutation had normal phenotypes. Two subjects had sensorineural deafness and were heterozygous for a single mutation. Goitre was found only in patients with Pendred's syndrome and was absent in all other individuals, albeit residing in an iodine-deficient area. CONCLUSIONS: We have identified a novel mutation in the pendrin gene causing Pendred's syndrome, and confirm that molecular analysis is a useful tool for a definitive diagnosis. This is particularly relevant in cases such as in the subjects of our family in which the clinical features might be misleading and other genetics factors might be responsible for deafness.

Low dose hexarelin and growth hormone (GH)-releasing hormone as a diagnostic tool for the diagnosis of GH deficiency in adults: comparison with insulin-induced hypoglycemia test.

GH deficiency (GHD) in adults must be shown by provocative testing of GH secretion. Insulin-induced hypoglycemia (ITT) is the test of choice, and severe GHD, treated with recombinant human GH replacement, is defined by a GH peak response to ITT of less than 3 microg/L. GHRH plus arginine (ARG) is a more provocative test and is as sensitive as ITT provided that appropriate cut-off limits are assumed. GH secretagogues are a family of peptidyl and nonpeptidyl GH-releasing molecules that strongly stimulate GH secretion and, even at low doses, truly synergize with GHRH. Our aim was to verify the diagnostic reliability of the hexarelin (HEX; 0.25 microg/kg, iv) and GHRH (1 microg/kg, iv) test for the diagnosis of adult GHD. To this goal, in the present study we 1) defined the normal ranges of the GH response to GHRH+HEX in a group of normal young adult volunteers (NS; n = 25; 18 men and 7 women; age, 28.5+/-0.6 yr) and in 11 of them verified its reproducibility in a second session, and 2) compared the GH response to GHRH+HEXwith that to ITT in a group of normal subjects (n = 33; 12 men and 21 women; age, 34.1+/-1.5 yr) and hypopituitaric adults with GHD (n = 19; 10 men and 9 women; age, 39.9+/-2.2 yr; GH peak <5 microg/L after ITT). The GH response to GHRH+ARG was also evaluated in all GHD and in 77 normal subjects (40 men and 37 women; age, 28.1+/-0.6 yr). The mean GH peak after GHRH+HEX in NS was 83.6+/-4.5 microg/L; the third and first percentile limits of the normal GH response were 55.5 and 51.2 microg/L, respectively). The GH response to GHRH+HEX in NS showed good intraindividual reproducibility. In GHD the mean GH peak after GHRH+HEX (2.6+/-0.7 microg/L) was similar to that after GHRH+ARG (3.6+/-1.0 microg/L), and both were higher (P < 0.001) than that after ITT (0.6+/-0.1 microg/L); the GH responses to GHRH+HEX were positively associated with those to ITT and GHRH+ARG. Analyzing individual GH responses, 100% had severe GHD after ITT (GH peak, <3 microg/L). After GHRH+HEX all GHD had GH peaks below the third percentile limit of normality appropriate for this test (i.e. 55.5 microg/L). Thirteen of 19 (68.4%) GHD subjects had GH peaks below 3 microg/L after GHRH+HEX but all 19 (100%) had GH peaks below the first percentile limit of normality (i.e. 51.2 microg/L). The GH responses to GHRH+HEX were highly concordant with those after GHRH+ARG. In conclusion, the present results define normal limits of the GH response to stimulation with low dose HEX+GHRH in normal adults and show that this test is as sensitive as ITT for the diagnosis of adult GHD provided that appropriate cut-off limits are considered.