Dynamic changes of central thyroid functions in the management of Cushing's syndrome

ABSTRACT Objective The aim of this study was to determine the frequency of central thyroid dysfunctions in Cushing's syndrome (CS). We also aimed to evaluate the frequency of hyperthyroidism due to the syndrome of the inappropriate secretion of TSH (SITSH), which was recently defined in patients with insufficient hydrocortisone replacement after surgery. Materials and methods We evaluated thyroid functions (TSH and free thyroxine [fT4]) at the time of diagnosis, during the hypothalamo-pituitary-adrenal axis recovery, and after surgery in 35 patients with CS. The patients were separated into two groups: ACTH-dependent CS (group 1, n = 20) and ACTH-independent CS (group 2, n = 15). Patients' clinical and laboratory findings were evaluated in five visits in the outpatient clinic of the endocrinology department. Results The frequency of baseline suppressed TSH levels and central hypothyroidism were determined to be 37% (n = 13) and 26% (n = 9), respectively. A negative correlation was found between baseline cortisol and TSH levels (r = -0.45, p = 0.006). All patients with central hypothyroidism and suppressed TSH levels showed recovery at the first visit without levothyroxine treatment. SITSH was not detected in any of the patients during the postoperative period. No correlation was found between prednisolone replacement after surgery and TSH or fT4 levels on each visit. Conclusion Suppressed TSH levels and central hypothyroidism may be detected in CS, independent of etiology. SITSH was not detected in the early postoperative period due to our adequate prednisolone replacement doses.

Clinical characteristics and follow-up of Korean patients with adrenal incidentalomas

BACKGROUND/AIMS: We investigated the clinical characteristics and follow-up findings of subjects with adrenal incidentalomas in a single, tertiary-care hospital in South Korea. METHODS: The study consisted of a retrospective analysis of 282 adrenal incidentaloma patients who underwent radiographic and endocrinological evaluations at Samsung Medical Center in Seoul, South Korea, between January 2004 and July 2011. RESULTS: Most (86.2%) of the subjects were found to have nonfunctioning tumors. Functioning tumors were seen in 39 patients (13.8%). Among them, 28 (9.9%) had subclinical Cushing syndrome (SCS), six (2.1%) had pheochromocytoma, and five (1.8%) had primary hyperaldosteronism. Malignant adrenal tumors were discovered in three cases: two (0.7%) were primary adrenal cancers, and one (0.4%) was a secondary metastasis from a lung cancer. Significant risk factors for functional tumors were female gender (odds ratio [OR], 3.386; 95% confidence interval [CI], 1.611 to 7.117; p = 0.0013) and a noncontrast attenuation value of > 10 Hounsfield units (OR, 2.806; 95% CI, 1.231 to 6.397; p = 0.0141). During follow-up (mean, 22.5 months) of 72 of the patients, three (4.2%) developed hormonal changes due to functional tumors. One was confirmed as pheochromocytoma by histopathology, and the others were diagnosed with SCS and followed routinely without surgical intervention. No malignant transformation was found in these patients. CONCLUSIONS: Based on these findings, initial hormonal and radiographic evaluations for adrenal incidentalomas appear to be more important than follow-up tests because functional or malignant changes are rare.

Controle hormonal dos adenomas hipofisários pela cirurgia transesfenoidal: evolução dos resultados nos primeiros cinco anos de experiência / Hormonal control of pituitary adenomas by transsphenoidal surgery: results of the first five years of experience

OBJETIVO: Avaliar os resultados iniciais de uma equipe cirúrgica no controle hormonal dos adenomas hipofisários secretores. MATERIAIS E MÉTODOS: Em cinco anos, foram operados 51 adenomas secretores (31 GH, 14 ACTH, 5 prolactina, 1 TSH). O controle hormonal foi GH basal < 2,5 ng/dL, cortisol livre urinário normal, redução dos níveis de prolactina, e T3 e T4 livre normais. RESULTADOS: As taxas de controle foram 36 por cento na acromegalia e 57 por cento no Cushing. Dois prolactinomas (40 por cento) normalizaram a prolactina. Os hormônios tiroidianos normalizaram no adenoma secretor de TSH. O controle do hipercortisolismo correlacionou-se com o tempo de experiência da equipe (p = 0,01). CONCLUSÃO: Nossos resultados, limitados aos primeiros anos de experiência cirúrgica, situam-se abaixo da variação reportada em grandes casuísticas com maior tempo de experiência. Ao longo do tempo, observou-se melhora progressiva nos níveis de cortisol urinário no pós-operatório inicial da doença de Cushing em função da experiência cirúrgica.

OBJECTIVE: To evaluate the initial results of a surgical team in the hormonal control of secreting pituitary adenomas. MATERIALS AND METHODS: In five years 51 functioning adenomas were operated (31 GH-secreting, 14 ACTH-secreting, 5 PRL-secreting and 1 TSH-secreting). Hormonal control was defined as GH < 2,5 ng/mL, normal free-urinary cortisol, lower prolactin and normal T3 and FT4. RESULTS: Control rates were 36 percent in acromegaly, and 57 percent in Cushing's disease. Two prolactinomas normalized prolactin levels. Thyroid hormone levels were normalized in the TSH-secreting adenoma. Control of hypercortisolism was positively correlated with years of experience (p = 0.01). CONCLUSION: Our results, although restricted to the beginning of our experience, lie below the reported range of other surgical series with much longer experience. During these years, there was a significant improvement in initial post surgery urinary cortisol levels in Cushing's disease as a function of surgical experience.

Dermatofitose por Tricophyton rubrum como infecção oportunista em pacientes com doença de Cushing / Dermatophytosis caused by Tricophyton rubrum as an opportunistic infection in patients with Cushing disease

O dermatófito Trichophyton rubrum é um agente comum nas micoses superficiais, podendo apresentar lesões extensas pauci-inflamatórias de evolução crônica, especialmente em imunocomprometidos. O hipercortisolismo, na síndrome de Cushing, aumenta o risco de infecções, resultado do efeito imunossupressor dos glicocorticóides. Os casos relatados apresentam duas formas distintas de dermatofitose, em pacientes com doença de Cushing, causadas por Tricophyton rubrum e posterior remissão após normalização da cortisolemia.

Trichophyton rubrum is a common agent found in superficial mycoses, which present ample nonin?ammatory lesions, with chronic evolution, especially in immunocompromised patients. The hypercortisolism in Cushing's syndrome increases the risk of infections as a result of the immunosuppressive effect of glucocorticoids. The reported cases here refer to two different types of dermatophytosis caused by Trichophyton rubrum in patients with Cushing's disease, resistant to antifungal treatment. The disease remitted after the levels of cortisol went back to normal.

Screening and diagnosis of Cushing's syndrome: [review]

Cushing's syndrome (CS) results from sustained pathologic hypercortisolism. The clinical features are variable and the most specific features for CS include abnormal fat distribution, particularly in the supraclavicular and temporal fossae, proximal muscle weakness, wide purple striae, and decreased linear growth with continued weight gain in a child. Clinical presentation of CS can be florid and in this case the diagnosis is usually straightforward. However, the diagnosis can be difficult particularly in states of mild or cyclical or periodical hypercortisolism. Several tests based on the understanding of the physiologic characteristics of the hypothalamic-pituitary-adrenal axis have been used extensively to confirm the diagnosis of Cushing's syndrome, but none has proven fully capable of distinguishing all cases of CS from normal and/or pseudo-Cushing individuals. Three first-line diagnostic tests are currently used to screen for CS: measurement of free cortisol in 24-hour urine (UFC), cortisol suppressibility by low doses of dexamethasone (DST), and assessment of cortisol circadian rhythm using late-night serum and/or salivary cortisol. This paper discusses the effectiveness regarding best cut-off values, the sensitivity and the specificity of these tests to screen for CS. Late-night salivary cortisol appears to be the most useful screening test. UFC and DST should be performed to provide further confirmation of the diagnosis.

A síndrome de Cushing (SC) resulta de um hipercortisolismo patológico mantido. As manifestações clínicas são variáveis e os achados mais específicos para a SC incluem distribuição anormal de gordura, particularmente nas fossas supraclaviculares e temporais, fraqueza muscular proximal, estrias purpúreas largas e interrupção do crescimento linear com ganho contínuo de peso na criança. A apresentação clínica da SC pode ser florida e, neste caso, o diagnóstico é usualmente direto. Entretanto, o diagnóstico pode ser dificultado particularmente em estados de hipercortisolismo leve ou cíclico/periódico. Vários testes baseados na compreensão das características fisiológicas do eixo hipotálamo-hipófise-adrenal têm sido usados extensivamente para confirmar o diagnóstico da SC, mas nenhum deles mostrou-se totalmente capaz de distinguir todos os casos de SC dos indivíduos normais e/ou portadores de pseudo-Cushing. Três testes diagnósticos de primeira linha são atualmente empregados para rastrear SC: a medida do cortisol livre em urina de 24-horas (CLU), a supressão do cortisol por doses baixas de dexametasona (TSD) e a avaliação do ritmo circadiano do cortisol usando a dosagem do cortisol sérico ou salivar às 23-24 hs. Este artigo discute a efetividade com relação aos melhores valores de corte e a sensibilidade e especificidade destes testes no rastreamento da SC. O cortisol salivar às 23-24 hs parece ser o teste mais útil de rastreamento. O CLU e o TSD devem ser realizados na tentativa de fornecer confirmação adicional ao diagnóstico.

Differential diagnosis of Cushing's syndrome: [review]

The differential diagnosis of Cushing's syndrome requires careful multidisciplinary interaction with a number of specialities, co-ordinated through endocrine centres with good experience of this condition. It is essential that the diagnosis of Cushing's syndrome be fully established before differential diagnosis is attempted. The endocrinologist needs to be aware of the pitfalls and advantages of the tests in use. We discuss the approach to the differential diagnosis of this challenging condition.

O diagnóstico diferencial da síndrome de Cushing requer uma interação multidisciplinar cuidadosa entre várias especialidades, coordenadas através de centros de endocrinologia com boa experiência nessa condição. É essencial que o diagnóstico da síndrome de Cushing seja estabelecido antes da tentativa de diagnóstico diferencial. O endocrinologista precisa estar atento às possíveis falhas e vantagens dos testes empregados. Nós discutiremos a abordagem do diagnóstico diferencial nessa condição desafiadora.

The role of bilateral inferior petrosal sinus sampling in the diagnosis of Cushing's syndrome

Adrenocorticotropin hormone (ACTH)-dependent Cushing's syndrome is most often due to a pituitary corticotroph adenoma, with ectopic ACTH-secreting tumors representing approximately 15 percent of cases. Biochemical and radiological techniques have been established to help distinguish between these two entities, and thus aid in the localization of the neoplastic lesion for surgical resection. The test that offers the highest sensitivity and specificity is bilateral inferior petrosal sinus sampling (BIPSS). BIPSS is an interventional radiology procedure in which ACTH levels obtained from venous drainage very near the pituitary gland are compared to peripheral blood levels before and after corticotropin hormone (CRH) stimulation. A gradient between these two locations indicates pituitary Cushing's, whereas the absence of a gradient suggests ectopic Cushing's. Accurate BIPSS results require hypercortisolemia to suppress normal corticotroph ACTH production and hypercortisolemia at the time of the BIPSS to assure excessive ACTH secretion. In some cases, intrapituitary gradients from side-to-side can be helpful to localize small corticotroph adenomas within the sella. BIPSS has rare complications and is considered safe when performed at centers with experience in this specialized technique.

A síndrome de Cushing (SC) ACTH-dependente é mais freqüentemente devida a um adenoma corticotrófico da hipófise, com os tumores ectópicos secretores de ACTH representando aproximadamente 15 por cento dos casos. Técnicas bioquímicas e radiológicas foram estabelecidas para permitir a distinção entre essas duas entidades e, assim, auxiliar na localização da lesão neoplásica para ressecção cirúrgica. O teste que oferece a mais alta sensibilidade e especificidade é a coleta bilateral de amostras de sangue do seio petroso inferior (BIPSS). BIPSS é um procedimento de intervenção radiológica no qual os níveis de ACTH obtidos da drenagem venosa bem próxima da hipófise são comparados com os níveis sanguíneos periféricos antes e após estímulo com corticorrelina (CRH). Um gradiente entre essas duas localizações indica SC hipofisário, enquanto a ausência de gradiente sugere SC ectópica. Resultados acurados na BIPSS requerem a presença de hipercortisolemia e que ela suprima normalmente a produção de ACTH pelo corticotrofos por ocasião da BIPSS para garantir a secreção excessiva de ACTH. Em alguns casos, os gradientes intra-hipofisários de um lado para outro podem ser úteis na localização de pequenos adenomas corticotróficos no interior da sela. A BIPSS raramente apresenta complicações, sendo considerada segura quando realizada em centros com experiência nessa técnica especializada.

Cushing's syndrome: aftermath of the cure

Cushing's syndrome (CS) is a chronic and systemic disease caused by endogenous or exogenous hypercortisolism, associated with an increase of mortality rate due to the clinical consequences of glucocorticoid excess, especially cardiovascular diseases. After cure, usually obtained by the surgical removal of the tumor responsible for the disease, the normalization of cortisol secretion is not constantly followed by the recovery of the clinical complications developed during the active disease, and it is often followed by the development of novel clinical manifestations induced by the fall of cortisol levels. These evidences were mostly documented in patients with pituitary-dependent CS, after surgical resection of the pituitary tumor. Indeed, despite an improvement of the mortality rate, metabolic syndrome and the consequent cardiovascular risk have been found to partially persist after disease remission, strictly correlated to the insulin resistance. Skeletal diseases, mainly osteoporosis, improve after normalization of cortisol levels but require a long period of time or the use of specific treatment, mainly bisphosphonates, to reach the normalization of bone mass. A relevant improvement or resolution of mental disturbances has been described in patients cured from CS, although in several cases, cognitive decline persisted and psychological or psychiatric improvement was erratic, delayed, or incomplete. On the other hand, development or exacerbation of autoimmune disorders, mainly thyroid autoimmune diseases, was documented in predisposed patients with CS after disease remission. The totality of these complications persisting or occurring after successful treatment contribute to the impairment of quality of life registered in patients with CS after disease cure.

A síndrome de Cushing (SC) é uma desordem sistêmica crônica causada por hipercortisolismo endógeno ou exógeno, associada a um aumento da taxa de mortalidade devido às conseqüências clínicas do excesso de glicocorticóides, especialmente a doença cardiovascular. Após a cura, usualmente obtida pela remoção cirúrgica do tumor responsável pela desordem, a normalização da secreção de cortisol não é sistematicamente seguida da recuperação das complicações clínicas desenvolvidas durante a fase ativa da doença, e é freqüentemente seguida pelo surgimento de novas manifestações clínicas induzidas pela queda dos níveis de cortisol. Estas evidências foram, na sua maioria, documentadas em pacientes com SC de origem hipofisária, após a ressecção cirúrgica do tumor na hipófise. Na verdade, a despeito de uma melhoria na taxa de mortalidade, a síndrome metabólica e seu conseqüente risco cardiovascular têm se mostrado parcialmente persistentes após a remissão da doença, em estrita relação com a resistência à insulina. Anormalidades esqueléticas, especialmente a osteoporose, melhoram após a normalização dos níveis de cortisol, mas requerem um longo tempo ou o uso de tratamento específico, principalmente bisfosfonatos, para se obter a normalização da massa óssea. Uma melhora significativa ou mesmo resolução dos distúrbios mentais têm sido descritos em pacientes curados da SC, embora em vários casos o declínio cognitivo persista e a melhora psicológica ou psiquiátrica tenham sido erráticas, demoradas ou incompletas. Por outro lado, o desenvolvimento ou exacerbação de processos autoimunes, em especial as doenças autoimunes da tiróide, foram documentadas em pacientes predispostos com SC, após a remissão da doença. A totalidade dessas complicações, persistentes ou ocorrendo após o tratamento bem sucedido, contribuem para um prejuízo da qualidade de vida registrado em pacientes com SC após a cura da doença.

Increased diagnostic probability of subclinical cushing’s syndrome in a population sample of overweight adult patients with type 2 diabetes mellitus

Endogenous Cushing’s Syndrome (CS) is unusual. Patients with subclinical CS (SCS) present altered cortisol dynamics without obvious manifestations. CS occurs in 2-3 percent of obese poorly controlled diabetics. We studied 103 overweight adult outpatients with type 2 diabetes to examine for cortisol abnormalities and SCS. All collected salivary cortisol at 23:00 h and salivary and serum cortisol after a 1 mg dexamethasone suppression test (DST). Patients whose results were in the upper quintile for each test (253 ng/dL, 47 ng/dL, and 1.8 mg/dL, respectively for the 23:00 h and post-DST saliva and serum cortisol) were re-investigated. Average values from the upper quintile group were 2.5-fold higher than in the remaining patients. After a confirmatory 2 mg x 2 day DST the investigation for CS was ended for 61 patients with all normal tests and 33 with only one (false) positive test. All 8 patients who had two abnormal tests had subsequent normal 24h-urinary cortisol, and 3 of them were likely to have SCS (abnormal cortisol tests and positive imaging). However, a final diagnosis could not to be confirmed by surgery or pathology. Although not confirmatory, the results of this study suggest that the prevalence of SCS is considerably higher in populations at risk than in the general population.

A síndrome de Cushing (SC) endógena é rara. Pacientes com SC subclínica (SCS) apresentam hipercortisolismo sem manifestações clínicas. SC ocorre em 2-3 por cento de diabéticos mal controlados. Estudamos 103 pacientes adultos obesos ambulatoriais com diabetes mellitus tipo 2 para avaliar alterações do cortisol e SCS. Todos coletaram cortisol salivar às 23:00 h e cortisol salivar e sérico após teste de supressão com 1 mg de dexametasona (DST). Pacientes cujos resultados de qualquer teste estavam no quintil superior (253 ng/dL, 47 ng/dL e 1,8 mg/dL, respectivamente para cortisol salivar 23:00 h e salivar e sérico pós-DST) foram reavaliados. Os valores médios desse grupo encontravam-se 2,5 vezes acima dos valores dos demais pacientes. Após um teste confirmatório com 2 mg x 2 dias DST, a investigação da SC foi encerrada para 61 pacientes com todos os testes normais e 33 com apenas um teste (falso) positivo. Todos os 8 pacientes com dois testes alterados apresentaram cortisol urinário normal, mas 3 deles mostraram maior probabilidade diagnóstica de SCS (hipercortisolismo e alterações em exames de imagem). Contudo, o diagnóstico final não pode ser confirmado por cirurgia ou patologia em nenhum deles. Embora não confirmatórios, os resultados deste estudo sugerem que a prevalência de SCS seja maior em populações de risco do que na população geral.

El cateterismo bilateral y simult neo de los senos petrosos inferiores en el diagnóstico diferencial del síndrome de Cushing / Bilateral inferior petrosal sinus sampling in the differential diagnosis of ACTH-dependent Cushing's syndrome

Background: The features of pituitary ACTH-dependent Cushing syndrome are often indistinguishable from those of occult ectopic ACTH-dependent Cushing syndrome (CS). Aim: To assess the diagnostic accuracy of bilateral inferior petrosal sinus sampling (BIPSS) in the differential diagnosis of ACTH-dependent Cushing's syndrome as compared with ACTH levels and the overnight high dose dexamethasone suppression test (HDDST). Material and methods: Retrospective review of medical records of 23 patients (aged 19 to 63 years, 16 women) with surgically proven CS, 20 pituitarymicroadenomas (CD) and 3 with occult ectopic ACTH secretion (EAS). Results: No tumor was identifiable by imaging techniques. Mean plasma ACTH values were higher in patients with EAS than in CD (103± 110.2 and 73.1±41.98 pg/mL respectively, p=NS). Three patients with EAS and 3 patients with CD did not suppress cortisol with the HDDST. The sensitivity of the test was 86 percent and the specificity 100 percent. To improve the diagnostic outcome of BIPSS, an stimulation with Desmopressin (9 fig i.v) was performed in 9 patients. The threshold for a pituitary source, was defined as an inferior petrosal sinus to peripheral ACTH basal and post Desmopression ratio >2. BIPSS was successfully carried out in 22 patients and no complications occurred. In 6 patients BIPSS failed to meet the threshold criteria. In 3 patients, bronchial carcinoid tumors which proved to synthesize ACTH, were removed. The diagnostic sensitivity of BIPSS greatly improved from 86 percent to 100 percent after Desmopressin stimulation. BIPSS accurately predicted the ¡ateralization of the microadenoma in 8 of 12 patients (66 percent). Conclusions: The combination of Desmopressin stimulation with BIPSS was useful for the differential diagnosis of ACTH-dependent Cushing's Syndrome. However, the preoperative location of pituitary microadenomas was poorly predicted by BIPSS.

Supresion nocturna con alta dosis de dexametasona y test de metopirona en el diagnostico etiologico del sindrome de Cushing / Night supression with high doses of dexamethasone and metyrapone tests for the etiological diagnosis of Cushing syndrome

El síndrome de Cushing (SC) es un trastorno grave aunque curable para el que se han propuesto diferentes estrategias de diagnóstico etiopatogénico. Entre ellas, los tests que exploran la regulación de la secreción de cortisol son de gran utilidad aunque no existe homogeneidad de criterios respecto a la elección de los mismos. En este estudio se investigaron 61 pacientes de 13-61 años con SC, quienes fueron classificados según hallazgos quirúrgicos, patológicos y evolución post-tratamiento, en: de origen pitutario 41, por tumor adrenal 16 y SC ectópico 4. En la totalidad de los pacientes se realizó una prueba de inhibición de la cortisolemia con una dosis nocturna de 8 mg de dexametasona. En 43 de ellos, se efectuó edemás un test metopirona con medición de 11-desoxicortisol sérico. Ambas pruebas evidenciaron valores elevados de sensibilidad, especificidad, índice de validez y poder predictivo positivo, obteniéndose los porcentajes mayores (97, 100, 98 y 100 por ciento, respectivamente) con su empleo conjunto. El uso combinado de ambos tests constituye un medio simple y con elevados criterios de validez para el diagnóstico etiológico del SC.

Incidence of Nelson's syndrome and residual adrenocortical function in patients of Cushing's disease after bilateral adrenalectomy.

Eighteen patients of Cushing's Disease, who had undergone bilateral "total" adrenalectomy 2 to 10 years back, were evaluated for residual adrenocortical function and for any evidence of Nelson's Syndrome. Surprisingly, all patients were discovered to have measurable plasma cortisol, albeit in the subnormal range. The standard criteria for accepting "completeness of adrenalectomy" were fulfilled in 16 patients. It was possible to wean one patient off replacement therapy. Thus, the dose of replacement steroids needs to be regulated according to the blood steroid levels in order to avoid unnecessary hypercortisolism. Radiological evidence of pituitary tumor diagnosed Nelson's Syndrome in 2 patients. Nelson's Syndrome was further suspected in 8 others who showed pigmentation. One of these had an enlarged sella and an erosion of the dorsum sellae, but had a normal CT scan. Another patient had evidence of incidental pituitary pathology (incidentaloma) which resolved spontaneously. Contrast enhanced CT scans of the sella are necessary for early detection of Nelson's Syndrome.

Síndrome de nelson: de uma consegüencia par uma convergência com a doença de cushing / Nelson syndrome: a consequence for a convergence with a cushing disease

Em 1958, a descriçao original da síndrome de nelson, incluia a presença de um tumor hipofisário secretor de ACTH, após o tratamento da doença de Cushing pela adrenalectomia bilaterial. Entretanto, hoje, reconhece-se que uma adenoma hipofisário está presente em cerca de 90 por cento dos casos de doença de Cushing, antes de qualquer tratamento. O objetivo desta revisao foi atualizar o conceito e os critérios diagnósticos da síndorme de Nelson. A etiopatogenia dos tumores corticotróficos e a resistência aumentada à retroalimentaçao negativa dos glicoforticóides nao estao totalmente esclarecidas. Embora os tumores da síndrome de Nelson sejam mais agressivos, aparentemente nao existem diferenças de natureza genética ou de processamento dos peptídeos derivados da POMC, entre os adenomas oriundos da doença de Cushing ou da síndrome de Nelson. Os limites biológicos se superpoem. Porém, é de interêsse prático o estabelecimento dos limites e critérios diagnóticos entre a doença de Cushing pós-adrenaloctomia e a síndrome de Nelson, principalmente para determinar a ocasiao da reexploraçao cirúrgica da hipófise. A primeira tem tumores geralmente nao visualizados, menores que 5mm e níveis plasmáticos de ACTH geralmente menores que 1000pg/ml. Na segunda, so níveis de ACTH sao iguais ou maiores que 1000 pg/ml, aos 12 meses pós-adrenalectomia, aumentando rapidamente para 2000 pg/ml ou mais, após o 2§ ano e apresentando-se, através do CT, como tumores em crescimento e iguais ou maiores que 8 mm. A evoluçao científico-tecnológica levou a uma convergência dos conceitos e dos limites diagnósticos entre a síndrome de Nelson e a doença de Cushing. (Arq Bras Endocrinol Metab 1994; 38/1:47-51).

Different effects of pyridostigmine on growth hormone (GH) response to GH-releasing hormone in endogenous and exogenous hypercortisolemic patients

1. Somatostatin may play a role in the inhibition of growth hormone (GH) response to GH-releasing hormone (GHRH) in hypercortisolism. To examine this hypothesis we studied the effect of pyridostigmine, a cholinergic agonist that decreases hypothalamic somatostatin, on the GH response to GHRH in 8 controls, in 6 patients with endogenous hypercortisolism (3 with Cushing's disease and 3 with adrenal adenomas) and in 8 patients with exogenous hypercortisolism (lupus erythematosus chronically treated with 20-60 mg/day of prednisone). Each subject received GHRH(1-29)NH2,100 micrograms iv twice, preceded by pyridostigmine (120 mg) or placebo, orally. 2. The GH response to GHRH was significantly blunted in all hypercortisolemic patients compared to controls both after placebo (GH peak, 5.8 +/- 1.6 vs 46.2 +/- 15.9 micrograms/l, mean +/- SEM) and after pyridostigmine (15.7 +/- 5.6 vs 77.2 +/- 19.8 micrograms/l). 3. The GH response was absent in endogenous hypercortisolemic patients compared to the exogenous group, both after placebo (2.2 +/- 0.3 vs 8.5 +/- 2.4 micrograms/l) and after pyridostigmine (4.9 +/- 2.5 vs 23.8 +/- 8.7 micrograms/l). The GH release after GHRH/pyridostigmine for the exogenous group was similar to the response of controls treated with GHRH/placebo. 4. These results confirm that the GH response to GHRH is blunted in hypercortisolism, although more pronounced in the endogenous group. Pyridostigmine partially reversed this inhibition in the exogenous group. Therefore, somatostatin may play a role in the inhibition of GHRH-induced GH release in exogenous hypercortisolemic states