RESUMO
OBJECTIVE: The objective of our study was to determine reference intervals and biologic variation for testosterone (T), free testosterone (fT), and free androgen index (FAI) in women with accurate methods and to test the discriminative value of these parameters in a polycystic ovary syndrome (PCOS)-population. METHODS: Serum was obtained daily during a normal menstrual cycle from 25 healthy women (677 data-points). A single serum sample was obtained from 44 PCOS-patients. T was measured by LCMS/MS and by Architect® 2nd generation T Immunoassay. Sex hormone-binding globulin was measured to calculate fT and FAI. Results: Reference intervals which were established in healthy women with an ovulatory menstrual cycle were T = 0.3-1.6 nmol/L and 0.5-2.0 nmol/L, fT = 5.2-26 pmol/L and 7.2-33 pmol/L, and FAI = 0.4-2.9 and 0.6-4.4, by LC-MS/MS and immunoassay, respectively. T, fT and FAI were higher in PCOS patients than in controls (p b 0.0001). The areas under the curve of receiver operator characteristic (ROC) plots were not different for T, fT, or FAI when T was measured by LCMS/MS versus immunoassay based on prediction of PCOS. FAI and fT were the strongest predictors of PCOS. CONCLUSIONS: When based upon the appropriate reference intervals and ROC analysis, LC-MS/MS and second generation immunoassay have equivalent clinical utility for the diagnosis of PCOS.
Assuntos
Androgênios/sangue , Análise Química do Sangue/normas , Síndrome do Ovário Policístico/sangue , Testosterona/sangue , Adolescente , Adulto , Feminino , Humanos , Gravidez , Valores de Referência , Adulto JovemRESUMO
Mutations in the GnRH receptor (GnRH-R) gene have been reported to cause idiopathic hypogonadotropic hypogonadism (IHH). Herein, we describe a 26-yr-old male with a mild phenotypic form of IHH, the fertile eunuch syndrome (IHH in the presence of normal testicular size and some degree of spermatogenesis), associated with a homozygous mutation (Gln106Arg) in the GnRH-R. This mutation, located in the first extracellular loop of the GnRH-R, has been previously shown to decrease but not eliminate GnRH binding. The proband had hypogonadal testosterone levels, detectable but apulsatile gonadotropin secretion, and a normal adult male testicular size of 17 mL at baseline. After only 4 months of treatment with hCG alone, he developed sperm in his ejaculate and his wife conceived. Following cessation of hCG therapy, the patient demonstrated reversal of his hypogonadotropism as evidenced by normal adult male testosterone levels and the appearance of pulsatile luteinizing hormone secretion. This case thus expands the emerging clinical spectrum of GnRH-R mutations, provides the first genetic basis for the fertile eunuch variant of IHH and documents the occurrence of reversible IHH in a patient with a GnRH-R mutation.
Assuntos
Eunuquismo/genética , Eunuquismo/fisiopatologia , Fertilidade , Homozigoto , Mutação/fisiologia , Receptores LHRH/genética , Adulto , Sequência de Bases/genética , Gonadotropina Coriônica/uso terapêutico , Eunuquismo/tratamento farmacológico , Hormônio Liberador de Gonadotropina/sangue , Hormônio Liberador de Gonadotropina/uso terapêutico , Gonadotropinas/metabolismo , Humanos , Masculino , Dados de Sequência Molecular , Linhagem , Remissão Espontânea , Testosterona/sangueRESUMO
The preponderance of evidence states that, in adult men, estradiol (E2) inhibits LH secretion by decreasing pulse amplitude and responsiveness to GnRH consistent with a pituitary site of action. However, this conclusion is based on studies that employed pharmacologic doses of sex steroids, used nonselective aromatase inhibitors, and/or were performed in normal (NL) men, a model in which endogenous counterregulatory adaptations to physiologic perturbations confound interpretation of the results. In addition, studies in which estrogen antagonists were administered to NL men demonstrated an increase in LH pulse frequency, suggesting a potential additional hypothalamic site of E2 feedback. To reconcile these conflicting data, we used a selective aromatase inhibitor, anastrozole, to examine the impact of E2 suppression on the hypothalamic-pituitary axis in the male. Parallel studies of NL men and men with idiopathic hypogonadotropic hypogonadism (IHH), whose pituitary-gonadal axis had been normalized with long-term GnRH therapy, were performed to permit precise localization of the site of E2 feedback. In this so-called tandem model, a hypothalamic site of action of sex steroids can thus be inferred whenever there is a difference in the gonadotropin responses of NL and IHH men to alterations in their sex steroid milieu. A selective GnRH antagonist was also used to provide a semiquantitative estimate of endogenous GnRH secretion before and after E2 suppression. Fourteen NL men and seven IHH men were studied. In Exp 1, nine NL and seven IHH men received anastrozole (10 mg/day po x 7 days). Blood samples were drawn daily between 0800 and 1000 h in the NL men and immediately before a GnRH bolus dose in the IHH men. In Exp 2, blood was drawn (every 10 min x 12 h) from nine NL men at baseline and on day 7 of anastrozole. In a subset of five NL men, 5 microg/kg of the Nal-Glu GnRH antagonist was administered on completion of frequent blood sampling, then sampling continued every 20 min for a further 8 h. Anastrozole suppressed E2 equivalently in the NL (136 +/- 10 to 52 +/-2 pmol/L, P < 0.005) and IHH men (118 +/- 23 to 60 +/- 5 pmol/L, P < 0.005). Testosterone levels rose significantly (P < 0.005), with a mean increase of 53 +/- 6% in NL vs. 56 +/- 7% in IHH men. Despite these similar changes in sex steroids, the increase in gonadotropins was greater in NL than in IHH men (100 +/- 9 vs. 58 +/- 6% for LH, P = 0.07; and 85 +/- 6 vs. 41 +/- 4% for FSH, P < 0.002). Frequent sampling studies in the NL men demonstrated that this rise in mean LH levels, after aromatase blockade, reflected an increase in both LH pulse frequency (10.2 +/- 0.9 to 14.0 +/- 1.0 pulses/24 h, P < 0.05) and pulse amplitude (5.7 +/- 0.7 to 8.4 +/- 0.7 IU/L, P < 0.001). Percent LH inhibition after acute GnRH receptor blockade was similar at baseline and after E2 suppression (69.2 +/- 2.4 vs. 70 +/- 1.9%), suggesting that there was no change in the quantity of endogenous GnRH secreted. From these data, we conclude that in the human male, estrogen has dual sites of negative feedback, acting at the hypothalamus to decrease GnRH pulse frequency and at the pituitary to decrease responsiveness to GnRH.
Assuntos
Inibidores da Aromatase , Inibidores Enzimáticos , Estrogênios/fisiologia , Hipotálamo/fisiologia , Adulto , Anastrozol , Dipeptídeos/farmacologia , Estradiol/sangue , Estradiol/fisiologia , Retroalimentação , Hormônio Foliculoestimulante/sangue , Hormônio Liberador de Gonadotropina/antagonistas & inibidores , Humanos , Hormônio Luteinizante/sangue , Masculino , Pessoa de Meia-Idade , Nitrilas , Testosterona/sangue , TriazóisRESUMO
Studies of sex steroid regulation of gonadotropin secretion in the human male have focused primarily on the respective site(s) of negative feedback of testosterone (T) and estradiol (E(2)). The use of pharmacological doses of sex steroids in these studies has precluded conclusions about the relative roles of T and E(2) in gonadotropin feedback. Thus, the aims of the present study were to 1) determine the relative contributions of T vs. E(2) to the sex steroid component of gonadotropin regulation, and 2) distinguish the feedback effects of T that that are direct (i.e. mediated by the androgen receptor) vs. indirect (mediated by aromatization to E(2)). Two experimental interventions were used: 1) inhibition of aromatization by a selective aromatase inhibitor to examine the impact of selective E(2) withdrawal; and 2) acute medical castration to examine the effect of ablating both T and E(2). Sixteen normal (NL) men (mean age, 30.5 +/- 2.2 yr) were studied. Nine NL subjects were treated with the aromatase inhibitor, anastrozole (10 mg, orally, daily, for 5 days). Twelve NL men underwent medical castration with ketoconazole (1-g loading dose followed by 400 mg, orally, four times a day for 5 days). Ketoconazole-treated subjects received concomitant treatment with dexamethasone (0.5 mg twice daily) to prevent the development of adrenal insufficiency. Single blood samples were drawn daily between 0800-1000 h. To ensure that dexamethasone was not altering the gonadotropin response to sex steroid ablation by a direct pituitary effect, five GnRH-deficient men (mean age, 37.6 +/- 3.9 yr) underwent GnRH dose-response studies at baseline and after treatment with dexamethasone (0.5 mg twice daily). Aromatase blockade caused significant lowering of E(2) (33 +/- 3 to 14 +/- 1 pg/mL; P: < 0.0005) with a corresponding increase in T levels (563 +/- 42 to 817 +/- 81 ng/dL; P: < 0.05). Treatment with ketoconazole resulted in equivalent suppression of E(2) (41 +/- 4 to 14 +/- 1 pg/mL; P: < 0.0005), but also induced castrate levels of T (491 +/- 28 to 40 +/- 3 ng/dL; P: < 0.0005). Both treatment regimens were associated with a significant increase in gonadotropin levels. For LH, the percent increase in serum levels after castration was almost 3-fold greater than that seen after selective E(2) withdrawal (275 +/- 23% with ketoconazole vs. 95.6 +/- 21% with anastrozole; P: < 0.005). Despite the divergent changes in T levels with these two maneuvers (a marked decrease after ketoconazole and a significant increase with anastrozole), the percent rise in FSH levels was similar in the two protocols (91 +/- 6% vs. 71 +/- 7%, respectively; P: = NS). Inhibin B levels were unchanged after selective E(2) withdrawal (156 +/- 23 vs. 176 +/- 19 pg/mL), but decreased slightly with ketoconazole (156 +/- 15 to 131 +/- 11 pg/mL; P: < 0.05). In contrast to the effects of glucocorticoid administration on gonadotropin secretion in women, no significant changes were observed in the GnRH-deficient men treated with dexamethasone in terms of mean LH levels (19.8 +/- 3.2 vs. 23.3 +/- 5.4 IU/L), mean LH pulse amplitude after GnRH (16.0 +/- 2.5 vs. 19.0 +/- 5.1 IU/L), or mean FSH levels (8.0 +/- 1.9 vs. 9.2 +/- 2.4 IU/L, pre vs. post). These studies provide evidence of differential regulation of gonadotropin secretion by T in the human male. T exerts both direct and indirect feedback on LH secretion, whereas its effects on FSH appear to be mediated largely by aromatization to E(2). From these data we conclude that in terms of sex steroid feedback, E(2) is the predominant regulator of FSH secretion in the human male.
Assuntos
Hormônio Foliculoestimulante/metabolismo , Hormônios Esteroides Gonadais/fisiologia , Testosterona/fisiologia , Adulto , Anastrozol , Inibidores da Aromatase , Dexametasona/farmacologia , Inibidores Enzimáticos/farmacologia , Antagonistas de Estrogênios/farmacologia , Retroalimentação , Glucocorticoides/farmacologia , Hormônios Esteroides Gonadais/antagonistas & inibidores , Gonadotropinas/metabolismo , Humanos , Cetoconazol/farmacologia , Hormônio Luteinizante/metabolismo , Masculino , Nitrilas/farmacologia , Testosterona/antagonistas & inibidores , Triazóis/farmacologiaRESUMO
Regulation of FSH secretion in the male involves a complex balance between stimulation by GnRH from the hypothalamus, inhibitory feedback by sex steroids (T and E2) and inhibin B (Inh B) from the gonads, and autocrine/paracrine modulation by activin and follistatin within the pituitary. The aim of the present study was to delineate the feedback control of FSH in the human male with specific reference to the relative roles of sex steroids vs. Inh B. Two experimental human models were used: 1) normal (NL) men subjected to acute sex steroid withdrawal (-T, -E2, + Inh B), and 2) functional castrate males (-T, -E2, -Inh B). Nine NL men (age range, 25-45 yr) and three castrate males (age range, 23-47 yr) were studied. The NL men underwent acute sex steroid suppression using high dose ketoconazole (1-g loading dose, followed by 400 mg, orally, four times daily for 150 h). Gonadotropin secretion was characterized by frequent blood sampling every 10 min for 12 h at baseline and on d 3 and 6 of sex steroid ablation. In the three castrate subjects, blood sampling was performed every 5 min for 24 h 8 wk after discontinuing androgen replacement therapy. In the NL men, treatment with ketoconazole resulted in a decline to castrate levels in T (451 +/- 20 to 38 +/- 7 ng/dl; P < 0.0005) and E2 (39 +/- 4 to 15 +/- 2 pg/ml; P < 0.005) and a modest, but significant, decline in Inh B levels, which remained within the normal range (183 +/- 19 to 136 +/- 13 pg/ml; P < 0.005). This suppression of sex steroids was associated with a more marked increase in mean LH (9.5 +/- 0.9 to 24.9 +/- 2.0 IU/liter; P < 0.0001) than FSH levels (5.1 +/- 0.7 to 10.0 +/- 1.5 IU/liter; P < 0.005), with the latter not exceeding the normal adult male range. The castrate subjects had a mean T level of 66 +/- 8 ng/dl, an E2 level of 20 +/- 1 pg/ml, and undetectable Inh B levels. Despite a similar sex steroid milieu, the mean FSH levels observed in NL men after acute sex steroid ablation were approximately 6-fold lower than those seen in the castrate subjects (10.0 +/- 1.5 vs. 59.5 +/- 17.7 IU/liter; P < 0.0005). In contrast, mean LH levels in the NL men were less than 3-fold lower than those in castrate subjects (24.9 +/- 2.0 vs. 66.8 +/- 20.1 IU/liter; P < 0.005). From this human model of acute sex steroid withdrawal, we conclude that Inh B is likely to be the major feedback regulator of FSH secretion in the human male.
Assuntos
Hormônio Foliculoestimulante/metabolismo , Inibinas/fisiologia , Adulto , Estradiol/sangue , Retroalimentação/fisiologia , Hormônio Foliculoestimulante/sangue , Antagonistas de Hormônios/farmacologia , Humanos , Inibinas/sangue , Cetoconazol/farmacologia , Hormônio Luteinizante/sangue , Masculino , Pessoa de Meia-Idade , Sistemas Neurossecretores/fisiologia , Orquiectomia , Testosterona/sangueRESUMO
The majority of patients with polycystic ovary syndrome (PCOS) exhibit an increase in both the frequency and amplitude of LH secretion, which is thought to contribute to the hyperandrogenism associated with this disorder. The increase in LH pulse amplitude may reflect either enhanced pituitary sensitivity to GnRH and/or an increase in hypothalamic GnRH secretion. To determine whether endogenous GnRH secretion is increased in PCOS and to document the degree and time course of androgen suppression after acute LH inhibition, the Nal-Glu GnRH antagonist was administered s.c. at 4 doses (5, 15, 50, and 150 micrograms/kg) to 11 women with PCOS. The response to GnRH receptor blockade was compared with data from regularly cycling women (n = 50) studied in the early and late follicular, and early luteal phases. The response to more prolonged GnRH receptor blockade was determined in a subset of patients, in whom 150 micrograms/kg of the GnRH antagonist was administered s.c. every 24 h for 3 days (n = 7) and continued for 7 days in 3 subjects. LH levels decreased in a dose-dependent fashion after administration of the GnRH antagonist (P < 0.0001), with a maximum percent inhibition of 83 +/- 2%. At all except the 5 micrograms/kg dose, mean LH levels remained significantly lower than baseline for up to 20 h post antagonist (P < 0.002). At all antagonist doses, both the degree and duration of LH suppression were similar in PCOS and normal women. The maximum percent inhibition of FSH was 39 +/- 2%, which was significantly less than that of LH (P < 0.001). Testosterone (T) levels fell significantly within 4 h of antagonist administration, with maximum percent inhibition of 39 +/- 3% occurring at 8 h. In the patients in whom 150 micrograms/kg of the antagonist was given for 3-7 days, no further suppression of either gonadotropins or T was noted. Our conclusions were: 1) The equivalent susceptibility of LH to submaximal GnRH receptor blockade in normal and PCOS women suggests that the elevated LH levels in PCOS are not the result of an increase in the quantity of GnRH secreted. These data imply that it is the frequency of GnRH stimulation per se and/or enhanced pituitary sensitivity to endogenous GnRH that underlie the gonadotropin abnormalities in PCOS; and 2) The rapid suppression of T with increasing GnRH antagonist dose is consistent with acute regulation of T secretion by LH.
Assuntos
Androgênios/metabolismo , Dipeptídeos , Antagonistas de Hormônios , Sistemas Neurossecretores/efeitos dos fármacos , Síndrome do Ovário Policístico/diagnóstico , Receptores LHRH/antagonistas & inibidores , Adolescente , Adulto , Relação Dose-Resposta a Droga , Estudos de Avaliação como Assunto , Feminino , Hormônio Foliculoestimulante/metabolismo , Humanos , Hormônio Luteinizante/metabolismo , Síndrome do Ovário Policístico/fisiopatologia , Taxa SecretóriaRESUMO
Although considerable strides have been made in charting the physiology and pathophysiology of inhibin in the human, further progress awaits the development of recombinant inhibin suitable for administration in human studies. Measurements of total serum inhibin, although inadequate to chart the dynamic changes associated with normal and disordered pituitary-gonadal function, have proven to be of value as indices of ovarian tumor activity. Although the roles of specific dimeric inhibin measurements in clinical practice have not been clearly established, advances in our understanding of inhibin physiology and pathophysiology in the human suggest that inhibin B may have value as a marker of Sertoli cell function in men with infertility and as a prognostic indicator in women undergoing ovulation induction therapy.
Assuntos
Hormônio Foliculoestimulante/metabolismo , Inibinas/fisiologia , Hormônio Luteinizante/metabolismo , Adulto , Animais , Feminino , Hormônio Liberador de Gonadotropina/farmacologia , Humanos , Inibinas/farmacologia , Masculino , Proteínas RecombinantesRESUMO
Nifedipine is a commonly used agent in treating hypertension and angina because of its vasodilator properties. An inhibitory role of nifedipine on aldosterone (Aldo) biosynthesis has been documented in in vitro studies. This study was designed to examine the impact of a sustained release nifedipine formulation on Aldo biosynthesis and its clinical consequences. Early and late effects of nifedipine on Aldo, PRA, and Aldo/PRA ratio levels were studied in a single blind, placebo-controlled, 10-day pilot study. Ten normotensive subjects and 10 patients with hypertension were studied. Blood samples for the measurement of Aldo and PRA were obtained at 2-h intervals for 10 h on a control day and on days 1 and 8 of nifedipine treatment for the determination of baseline, early, and late values. Placebo was administered at 0800 h on the first and second days of the study, whereas nifedipine (60 mg/day) was given for the following 8 days. The Aldo/ PRA ratio was used as a sensitive indirect index of the responsiveness of Aldo secretion to adrenal stimulation with angiotensin. Compared to those on the control day, a significant rise in the integrated PRA levels occurred on the first day of nifedipine treatment, with a further rise observed on the eighth day of the treatment in the normotensive subjects (1.1 +/- 0.6, 1.7 +/- 1.2, and 2.5 +/- 1.8 ng/mL.h on the control day and the first and eighth days of treatment, respectively; P < 0.05) and by the eighth day in the hypertensive subjects (2.2 +/- 2.8 and 4.0 +/- 4.1 ng/mL.h; P < 0.05). A significant rise in integrated Aldo levels occurred in the normotensive subjects on the eighth day of nifedipine treatment (control day, 319 +/- 187; eighth day of nifedipine, 363 +/- 167 pmol/L; P < 0.05) and in the hypertensive subjects (426 +/- 219 and 535 +/- 284 pmol/L; P < 0.05). This was associated with a significant lowering of the Aldo/PRA ratio on the first day of the treatment, with further lowering on the eighth day in the normotensive (435 +/- 454, 269 +/- 209, and 182 +/- 107; P < 0.05) and by the eighth day in the hypertensive subjects (716 +/- 833 and 305 +/- 315; P < 0.05). When individual time points were examined in the normotensive subjects, Aldo/PRA levels were significantly lower on day 8 of nifedipine treatment at 1000, 1200, and 1400 h than corresponding values on the control day. The fall in the Aldo/PRA ratio during nifedipine treatment indicates that the previously reported in vitro inhibition of Aldo biosynthesis in adrenal cells is reproduced in vivo. In the absence of nifedipine, it is likely that Aldo levels would be higher for any given level of PRA. It is probable that the Aldo inhibition and the vasodilatatory effect of nifedipine combine to bring about the lowering of blood pressure. Drugs that inhibit renin-angiotensin axis activity are likely to be particularly effective when additional lowering of blood pressure is required.
Assuntos
Aldosterona/metabolismo , Hipertensão/tratamento farmacológico , Nifedipino/uso terapêutico , Sistema Renina-Angiotensina/efeitos dos fármacos , Vasodilatadores/uso terapêutico , Idoso , Aldosterona/sangue , Pressão Sanguínea/efeitos dos fármacos , Preparações de Ação Retardada , Feminino , Humanos , Hipertensão/sangue , Hipertensão/fisiopatologia , Masculino , Pessoa de Meia-Idade , Nifedipino/administração & dosagem , Valores de Referência , Renina/sangue , Fatores de Tempo , Resultado do TratamentoRESUMO
A pulsatile pattern of GnRH stimulation is essential for normal secretion of luteinizing hormone (LH), while both continuous and fast-frequency GnRH stimulation result in a paradoxical decrease in gonadotrope responsiveness known as desensitization. Under physiological conditions there is striking concordance between the pulsatile secretion of LH and the glycoprotein free alpha-subunit (FAS). The aims of this study were to determine whether the FAS response to GnRH is also decreased at fast frequencies of GnRH stimulation and whether FAS is superior to LH as a marker of GnRH secretory activity at fast-pulse frequencies. The model of GnRH-deficient men was chosen to permit precise control of the dose and frequency of GnRH stimulation of the gonadotrope. The frequency of i.v. administration of GnRH to 5 GnRH-deficient men was progressively increased from every 120 to every 60 min, from 60 to 30 min, and from 30 to 15 min during three 12-h admissions, 1 week apart. The bolus dose of GnRH remained constant and was set at that dose previously shown to produce physiological concentrations and amplitudes of LH secretion and normal testosterone levels. As the frequency of GnRH stimulation was increased, a progressive rise in mean FAS levels was noted (353 +/- 13, 448 +/- 42, 466 +/- 50, and 698 +/- 85 ng/L [mean +/- SEM] for 120, 60, 30, and 15 min intervals; P < 0.005). However, normalization of mean FAS levels to account for the increase in total GnRH delivered with increasing frequencies revealed a progressive decrease in pituitary responsiveness to each GnRH bolus with increasing frequency of stimulation (353 +/- 13, 224 +/- 21, 117 +/- 13, 87 +/- 11 ng/L; P < 0.001). The decrease in normalized mean levels was supported by a decrease in the FAS pulse amplitude with increasing frequency (517 +/- 53, 365 +/- 50, 176 +/- 29 ng/L for 120, 60, and 30 min intervals, respectively; P < 0.005). At interpulse intervals of 120 and 60 min, there was complete concordance of LH and FAS pulses in response to GnRH. However, at the 30-min frequency FAS proved to be a better marker of GnRH with a higher true positive rate and lower number of false positives than LH (P < 0.05). At all frequencies, the number of false positive pulses detected tended to be lower for FAS than for LH (P = 0.06). From these data we conclude that FAS is subject to desensitization in response to increasing frequencies of GnRH administration in GnRH-deficient men, but is superior to LH as a surrogate marker of GnRH pulse generator activity at fast pulse frequencies.
Assuntos
Subunidade alfa de Hormônios Glicoproteicos/análise , Hormônio Liberador de Gonadotropina/metabolismo , Hormônio Liberador de Gonadotropina/farmacologia , Hormônio Luteinizante/análise , Adulto , Biomarcadores , Relação Dose-Resposta a Droga , Resistência a Medicamentos , Hormônios Esteroides Gonadais/sangue , Hormônio Liberador de Gonadotropina/deficiência , Humanos , Masculino , Fluxo Pulsátil , Valores de Referência , Fatores de TempoRESUMO
Kallmann syndrome (KS) consists of congenital, isolated, idiopathic hypogonadotropic hypogonadism (IHH) and anosmia. The gene responsible for the X-linked form of KS, KAL, encodes a protein, anosmin, that plays a key role in the migration of GnRH neurons and olfactory nerves to the hypothalamus. In addition to X-linked pedigrees, autosomal dominant and recessive kindreds with KS have been reported. The relative importance of these autosomal vs. X-linked genes in producing KS, and the frequency of KAL mutations, are currently unknown because these are rare disorders and large series are unusual. We examined 101 individuals with IHH (+/- anosmia) and their families to determine their modes of inheritance, incidence of mutations in the coding sequence of KAL, genotype-phenotype correlations, and [in a subset (n = 38)] their neuroendocrine phenotype. Of the 101 patients, 59 had true KS (IHH + anosmia/hyposmia); whereas, in the remaining 42, no anosmia was evident in the patients or their families. Of the 59 KS patients, 21 were familial, whereas 38 were sporadic cases. Mutations in the coding sequence of KAL were identified in only 3 of 21 familial cases (14%) and 4 of 38 (11%) of the sporadic cases. Of the X-linked cases confirmed by mutational analysis, only 1 of 3 pedigrees appeared X-linked by inspection whereas the other 2 contained only affected brothers. Female members of known KAL mutation families (n = 3) exhibited no reproductive phenotype and were not anosmic, whereas families with anosmic women (n = 3) were not found to carry mutations in KAL. Mutations were uniformly absent in nonanosmic IHH probands (n = 42), as well as in families with both anosmic and nonanosmic members (n = 2). Overall, 4 novel mutations were identified (C172R, R191x, R457x, and delC@L600). With respect to neuroendocrine phenotype, KS men with documented KAL mutations (n = 8) had completely apulsatile LH secretion, whereas those with autosomal modes of inheritance demonstrated a more variable spectrum with evidence of enfeebled (but present) GnRH-induced LH pulses. Our conclusions are: 1) Confirmed mutations in the coding sequence of the KAL gene occur in the minority of KS cases, i.e. only 14% of familial and 11% of sporadic cases; 2) The majority of familial (and presumably sporadic) cases of KS are caused by defects in at least two autosomal genes that are currently unknown; 3) Obligate female carriers in families with KAL mutations have no discernible phenotype; 4) KAL mutations are uniformly absent in patients with either normosmic IHH or in families with both anosmic and nonanosmic individuals; and 5) Patients with KAL mutations have apulsatile LH secretion consistent with a complete absence of GnRH migration of GnRH cells into the hypothalamus, whereas evidence of present (but enfeebled) GnRH-induced LH pulses may be present in autosomal KS cases. Taken together, these findings suggest that autosomal genes account for the majority of familial cases of KS, and that unique neuroendocrine phenotypes consistent with some GnRH neuronal migration may exist in these patients.
Assuntos
Síndrome de Kallmann/genética , Síndrome de Kallmann/fisiopatologia , Sistemas Neurossecretores/fisiopatologia , Adulto , Genótipo , Humanos , Masculino , Mutação , Linhagem , Fenótipo , Polimorfismo GenéticoRESUMO
Mutations in the GnRH receptor (GNRHR) have been described as a cause of reproductive failure in a subset of patients with idiopathic hypogonadotropic hypogonadism (IHH). Given the apparent rarity of these mutations, we set out to determine the frequency and distribution of GNRHR mutations in a heterogeneous population of patients with IHH who were well characterized with respect to diagnosis, phenotype, and mode of inheritance and to define their distribution within the receptor protein. One hundred and eight probands with IHH were screened for mutations in the coding sequence of GNRHR. Forty-eight of the 108 patients had a normal sense of smell, whereas the remaining 60 had anosmia or hyposmia (Kallmann syndrome). Exon segments in the GNRHR were screened for mutations using temperature gradient gel electrophoresis, and all mutations were confirmed by direct sequencing. Five unrelated probands (3 men and 2 women), all normosmic, were documented to have changes in the coding sequence of the GNRHR. Two of these probands were from a subgroup of 5 kindreds consistent with a recessive mode of inheritance, establishing a GNRHR mutation frequency of 2 of 5 (40%) in patients with normosmic, autosomal recessive IHH. The remaining 3 probands with GNRHR mutations were from a subgroup of 18 patients without evidence of familial involvement, indicating a prevalence of 3 of 18 (16.7%) in patients with sporadic IHH and a normal sense of smell. Among the five individuals bearing GNRHR mutations, a broad spectrum of phenotypes was noted, including testicular sizes in the male that varied from prepubertal to the normal adult male range. Three probands had compound heterozygous mutations, and two had homozygous mutations. Of the eight DNA sequence changes identified, four were novel: Thr(32)Ile, Cys(200)Tyr, Leu(266)Arg, and Cys(279)TYR: COS-7 cells transiently transfected with complementary DNAs encoding the human GNRHR containing each of these four novel mutations failed to respond to GnRH agonist stimulation. We conclude that 1) the spectrum of phenotypes in patients with GNRHR mutations is much broader than originally anticipated; 2) the frequency of GNRHR mutations may be more common than previously appreciated in familial cases of normosmic IHH and infrequent in sporadic cases; and 3) functional mutations of the GNRHR are distributed widely throughout the protein.
Assuntos
Hipogonadismo/genética , Mutação , Receptores LHRH/genética , Sequência de Aminoácidos/genética , Animais , Sequência de Bases/genética , Células COS , Feminino , Frequência do Gene , Genes Recessivos , Heterozigoto , Homozigoto , Humanos , Hipogonadismo/fisiopatologia , Masculino , Dados de Sequência Molecular , Mutação/genética , Fenótipo , Polimorfismo Genético , OlfatoRESUMO
This article outlines the changing pattern of gonadotropin-releasing hormone (GnRH)-induced gonadotropin secretion across sexual development, a knowledge of which is critical to understanding GnRH secretion in pathologic states such as hypogonadotropic hypogonadism. The clinical presentation, differential diagnosis, and treatment of hypogonadotropic hypogonadism in humans are discussed. Particular emphasis is placed on the contribution of frequent sampling studies of gonadotropin secretion and genetic studies to understanding the pathophysiology and clinical heterogeneity of isolated GnRH deficiency in humans.
Assuntos
Hormônio Liberador de Gonadotropina/deficiência , Hipogonadismo/etiologia , Envelhecimento , Animais , Diagnóstico Diferencial , Feminino , Feto/fisiologia , Hormônio Liberador de Gonadotropina/genética , Hormônio Liberador de Gonadotropina/metabolismo , Humanos , Hipogonadismo/diagnóstico , Hipogonadismo/fisiopatologia , Hipogonadismo/terapia , Hormônio Luteinizante/metabolismo , MasculinoRESUMO
Reports of concurrent thyrotoxicosis and thyroid cancer have appeared in the last three decades. While most of the tumours have been clinically inconsequential, it has been suggested that thyroid carcinomas arising in patients with Graves' disease tend to behave aggressively, while those associated with toxic nodular goitre follow a more benign course. We report a contrary clinical experience with four cases of thyrotoxicosis associated with metastatic thyroid cancer, two of which were fatal. All four patients had toxic nodular goitre. Thyroid eye signs were uniformly absent. Two patients had received 131I therapy; none had other history of irradiation to the head or neck. Antimicrosomal and antithyroglobulin antibodies were absent in all four patients. Thyroid-simulating immunoglobulin, which was measured in one patient, was also absent. Histopathological examination of the resected thyroid glands revealed two papillary cancers. one mixed anaplastic/papillary and one anaplastic cancer. All four patients had cervical node involvement and one had pulmonary metastases. Both patients with anaplastic carcinoma succumbed to their disease within 6 months: neither of the patients with papillary cancer had disease recurrence after 2 and 4 years, respectively. The experience reported here of aggressive thyroid cancer associated with toxic nodular goitre may represent coincidence or, alternatively, it may represent the early recognition of a change in the natural history of toxic nodular goitre.
Assuntos
Carcinoma/complicações , Bócio/complicações , Neoplasias da Glândula Tireoide/complicações , Tireotoxicose/complicações , Adulto , Idoso , Carcinoma/patologia , Carcinoma/secundário , Carcinoma Papilar/complicações , Evolução Fatal , Feminino , Humanos , Metástase Linfática , Pessoa de Meia-Idade , Neoplasias da Glândula Tireoide/patologia , Neoplasias da Glândula Tireoide/secundárioRESUMO
While individual hypopituitary patients undoubtedly benefit from growth hormone (GH) therapy, there is considerable variability in the response to treatment. Given the expense, possible lack of benefit, and potential risks associated with long-term therapy, we sought to identify characteristics potentially associated with a favorable response to GH replacement. Twelve GH-deficient adults (seven men and five women aged 35.4+/-2.5 years, mean +/- SEM) participated in a 12-month open study of GH replacement (0.125 IU/kg/wk for 4 weeks and 0.25 IU/kg/wk thereafter) designed to examine the impact of GH on body composition, lipid profile, and psychological well-being. Using bioelectrical impedance analysis (BIA), there was a reduction in body fat (BF) and an increase in lean body mass (LBM) and total body water (TBW) (P < .05) following 12 months of GH treatment. In addition, there was a significant improvement in psychological well-being as indicated by a decrease in the Nottingham Health Profile (NHP) score (P < .05) and a decrease in both total cholesterol (P = .005) and low-density lipoprotein (LDL) cholesterol (P < .03). GH therapy was associated with an increase in fasting plasma glucose (P = .008) and hemoglobin A1c (HbA1c (P = .06). When analyzed by gender, the beneficial effect of GH was greater in men versus women for the increment in insulin-like growth factor-1 ([IGF-1] 375+/-59 v 148+/-73 microg/L, mean +/- SEM), increase in LBM (6.8+/-2.5 v -0.06+/-1.6 kg), reduction in BF (5.6+/-1.6 v 1.0+/-1.9 kg), and increase in TBW (5.0+/-1.6 v 0.14+/-1.29 L) (P < .05). HbA1c increased significantly in women (P < .05). The beneficial effect of GH tended to be greatest in those with the most significant abnormality in baseline values (P < .05). The duration of hypopituitarism showed an indirect correlation with the change in total cholesterol (P < .005). Baseline IGF-1 levels correlated directly with changes in TBW (P < .05). These data indicate that men with GH deficiency appear more responsive to GH therapy than women with respect to the increase in IGF-1 levels and improvement in body composition. In general, patients with the most significant abnormality in baseline values, the highest IGF-1 levels, and the shortest duration of hypopituitarism respond best. With long-term GH therapy, careful monitoring of glucose tolerance is indicated.
Assuntos
Hormônio do Crescimento/uso terapêutico , Terapia de Reposição Hormonal , Hormônio do Crescimento Humano/uso terapêutico , Hipopituitarismo/tratamento farmacológico , Tecido Adiposo/efeitos dos fármacos , Tecido Adiposo/metabolismo , Adulto , Glicemia/metabolismo , Composição Corporal/efeitos dos fármacos , Água Corporal/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , Feminino , Hemoglobinas Glicadas/metabolismo , Hormônio do Crescimento/efeitos adversos , Terapia de Reposição Hormonal/efeitos adversos , Hormônio do Crescimento Humano/efeitos adversos , Hormônio do Crescimento Humano/deficiência , Humanos , Fator de Crescimento Insulin-Like I/metabolismo , Masculino , Fatores SexuaisRESUMO
A rapid HPLC-electrospray mass spectrometric assay for the quantitation of oxymetazoline in whole rat blood has been developed. Sample preparation was a single liquid-liquid extraction after addition of a deuterated internal standard (IS) and pH adjustment. An aliquot of reconstituted extract was injected onto a narrow-bore octadecyl reversed-phase column at a flow-rate of 400 microliters/min. Using a 20:1 post-column split, 5% of the eluent was introduced into the mass spectrometer interface. Elution of the analyte and IS occurred in less than 2 min. This rapid separation was made possible because of the sample cleanup and the selectivity of the mass spectrometric detection. The [M+H]+ ions for oxymetazoline (m/z 261) and [2H9]oxymetazoline (m/z 270) were detected using selected ion monitoring. The linear range of the assay was 0.67-167 ng/g of blood and the limit of quantitation with a 0.30-g sample was 1.0 ng/g. The assay permitted the analysis of nine samples per hour with the requisite sensitivity and selectivity and was used to determine the blood pharmacokinetics of oxymetazoline in rats dosed via intravenous and intranasal routes.
Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Espectrometria de Massas/métodos , Oximetazolina/sangue , Animais , Oximetazolina/farmacocinética , Ratos , Reprodutibilidade dos TestesRESUMO
We describe two patients with type 2 diabetes who presented with abdominal pain secondary to thoracic polyradiculopathy. In the first patient abdominal pain occurred in association with marked abdominal distension; extensive negative gastrointestinal investigations were performed before the correct diagnosis was made by electromyography showing thoracic paraspinal muscle denervation. In the second case, truncal sensory symptoms alone were evident at the time of diagnosis of diabetes mellitus. While muscle laxity was absent, extensive paraspinal muscle denervation was detected. Tolrestat, an aldose reductase inhibitor, was associated with good clinical response of symptoms due to peripheral neuropathy and thoracic polyradiculopathy. The pathogenesis of thoracic polyradiculopathy is uncertain but is likely to be the result of multiple infarcts along the course of thoracic spinal nerves accounting.
Assuntos
Músculos Abdominais/inervação , Neuropatias Diabéticas/diagnóstico , Idoso , Diabetes Mellitus Tipo 1 , Humanos , MasculinoRESUMO
Medical records of 132 patients attending an adult cystic fibrosis (CF) clinic were analysed to define the prevalence and clinical significance of diabetes mellitus (DM) in CF. Eighty four (63.6%) had normal blood glucose levels, 30 (22.8%) had hyperglycaemia only during intercurrent illness and 18 (13.6%) had DM. No significant differences were noted between the diabetic and non-diabetic groups for age, gender, height, weight, body mass index (BMI), forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) and pancreatic supplementation. Patients with hyperglycaemia during intercurrent illness had significantly lower BMI, FEV1% and FVC% than those with normal blood glucose levels. Of the diabetics four were managed on diet, three received oral hypoglycaemic agents and eleven were insulin requiring. The prevalence of DM in CF is considerable, severity of CF does not correlate with development of overt DM, and CF patients should be screened for DM by an oral glucose tolerance test on reaching adulthood.
Assuntos
Fibrose Cística/complicações , Complicações do Diabetes , Adulto , Humanos , Estudos RetrospectivosRESUMO
Medical records of 132 patients attending an adult cystic fibrosis (CF) clinic were analysed to define the prevalence and clinical significance of diabetes mellitus (DM) in CF. Eighty four (63.6%) had normal blood glucose levels, 30 (22.8%) had hyperglycaemia only during intercurrent illness and 18 (13.6%) had DM. No significant differences were noted between the diabetic and non-diabetic groups for age, gender, height, weight, body mass index (BMI), forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) and pancreatic supplementation. Patients with hyperglycaemia during intercurrent illness had significantly lower BMI, FEV1% and FVC% than those with normal blood glucose levels. Of the diabetics four were managed on diet, three received oral hypoglycaemic agents and eleven were insulin requiring. The prevalence of DM in CF is considerable, severity of CF does not correlate with development of overt DM, and CF patients should be screened for DM by an oral glucose tolerance test on reaching adulthood.