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.

Pitfalls in the diagnosis of Cushing's syndrome: [review]

Among endocrine disorders, Cushing's syndrome (CS) is certainly one of the most challenging to endocrinologists due to the difficulties that often appear during investigation. The diagnosis of CS involves two steps: confirmation of hypercortisolism and determination of its etiology. Biochemical confirmation of the hypercortisolaemic state must be established before any attempt at differential diagnosis. Failure to do so will result in misdiagnosis, inappropriate treatment, and poor management. It should also be kept in mind that hypercortisolism may occur in some patients with depression, alcoholism, anorexia nervosa, generalized resistance to glucocorticoids, and in late pregnancy. Moreover, exogenous or iatrogenic hypercortisolism should always be excluded. The three most useful tests to confirm hypercortisolism are the measurement of 24-h urinary free cortisol levels, low-dose dexamethasone-suppression tests, and determination of midnight serum cortisol or late-night salivary cortisol. However, none of these tests is perfect, each one has different sensitivities and specificities, and several are usually needed to provide a better diagnostic accuracy. The greatest challenge in the investigation of CS involves the differentiation between Cushing's disease and ectopic ACTH syndrome. This task requires the measurement of plasma ACTH levels, non-invasive dynamic tests (high-dose dexamethasone suppression test and stimulation tests with CRH or desmopressin), and imaging studies. None of these tests had 100 percent specificity and their use in combination is usually necessary. Bilateral inferior petrosal sinus sampling is mainly indicated when non-invasive tests do not allow a diagnostic definition. In the present paper, the most important pitfalls in the investigation of CS are reviewed.

Entre as doenças endócrinas, a síndrome de Cushing (SC) é certamente uma das mais desafiadoras para o endocrinologista, devido às dificuldades que comumente surgem durante a investigação. O diagnóstico de SC envolve dois passos: a confirmação do hipercortisolismo e a determinação de sua etiologia. A confirmação bioquímica do excesso de cortisol precisa ser estabelecida antes de qualquer tentativa de diagnóstico diferencial; caso contrário, poderá resultar em diagnóstico incorreto, tratamento impróprio e manejo insuficiente. Deve também ser lembrado que hipercortisolismo pode ocorrer em certos pacientes com depressão, alcoolismo, anorexia nervosa, resistência generalizada aos glicocorticóides e no final da gravidez. Além disso, hipercortisolismo exógeno ou iatrogênico deverá ser sempre excluído. Os três testes mais úteis para a confirmação do hipercortisolismo são: a medida do cortisol livre em urina de 24 h, os testes de supressão com dexametasona (TSD) em doses baixas e a determinação do cortisol sérico à meia-noite ou do cortisol salivar no final da noite. Contudo, nenhum deles é perfeito, cada um com sua sensibilidade e especificidade, sendo vários deles usualmente necessários para fornecer uma melhor acurácia diagnóstica. O maior desafio na investigação da SC envolve a diferenciação entre a doença de Cushing e a síndrome do ACTH ectópico. Esta tarefa requer a medida dos níveis plasmáticos de ACTH, testes dinâmicos não-invasivos (TSD com doses altas e testes de estímulo com CRH ou desmopressina) e estudos de imagem. Nenhum desses testes tem 100 por cento de especificidade e muitas vezes é necessário seu uso combinado. Amostragem venosa do seio petroso inferior está indicada principalmente quando os testes não-invasivos não permitem uma definição diagnóstica. Neste artigo, revisaremos as mais importantes armadilhas na investigação da SC.

Ketoconazole therapy: an efficacious alternative to achieve eucortisolism in patients with Cushing's syndrome

El síndrome de Cushing (SC) es un trastorno grave que requiere frecuentemente tratamiento medicamentoso. Cincuenta y cuatro pacientes (44 mujeres, 10 varones) de 14-63 años de edad con SC, recibieron ketoconazol (KTZ) previo a cirugía (n=27), como complemento luego de cirugía y/o radioterapia (n=16), o como tratamiento primario (n=11). La dosis de mantenimiento fue de 600 (500 - 600) mg/día (mediana-IC95) durante 15 días a 13 años. Los signos clínicos, hepatograma y cortisol libre urinario (CLU) fueron evaluados antes y durante tratamiento con KNZ. El CLU cayó a valores normales o subnormales en 85% de los pacientes, 5 a 150 días luego de iniciar el tratamiento; aún sin normalizar, el CLU disminuyó a 12-48% de los valores pre-tratamiento en el resto de los pacientes acompañándose de mejoría de los signos clínicos. Los efectos colaterales fueron: insuficiencia adrenal (18.5%), toxicidad hepática reversible (11%), "rash" cutáneo (5.5%) e intolerancia gástrica (3.7%); en 11% de los pacientes se observó un fenómeno de "escape". Veinticuatro pacientes (44.4%) fueron tratados por períodos prolongados, de uno a trece años. Este estudio confirma que el KTZ constituye un tratamiento eficaz y generalmente bien tolerado del SC, en particular: a) como preparación para cirugía b) en casos de hipercortisolismo residual luego de cirugía o en espera de resultados de radioterapia, c) como una alternativa razonable en pacientes con SC de origen desconocido y, d) como tratamiento crónico en casos de hipercortisolismo no resuelto luego de fracaso de las terapéuticas habituales.

Cushing's syndrome (CS) is a serious condition requiring drug management in diverse clinical settings. Fifty four patients (44 females, 10 males) with CS, aged 14-63, received ketoconazole (KTZ) prior to surgery (n= 27), as complementary therapy after surgery and/or radiotherapy (n= 16), or as primary treatment (n= 11). It was given at a 600 (500 - 600) mg/day (median - CI95) maintenance dose for periods ranging from 15 days to 13 years. Clinical signs, hepatic enzymes and urinary free cortisol (UFC) were evaluated before and during KTZ treatment. UFC normalised or decreased to subnormal values in 85% of the patients, in 5 to 150 days after starting treatment; although failing to normalise, UFC decreased to 12-48% of pre-treatment values in the remaining patients. Clinical signs improved throughout. Side effects were adrenal insufficiency (18.5%), reversible hepatic toxicity (11%), allergic skin rash (5.5%) and gastric intolerance (3.7%); in 11% of patients, an "escape phenomenon" was observed. Twenty-four out of the total (44.4%) were treated for prolonged periods, from one up to 13 years. In conclusion, this study confirms that KTZ is an effective and generally well tolerated treatment for CS particularly: a) shortly before surgery, b) because of persistent hypercortisolism after surgery or awaiting the results of radiotherapy, c) as a reasonable option in patients with CS of unknown aetiology and, d) as long-term therapy in any case of unsolved hypercortisolism after failure of current treatments.

THE CHANGES IN PLASMA ACTH, SERUM CORTISOL AND UFC IN PATIENTS WITH ADRENAL INSUFFICIENCY / 解放军医学杂志

To evaluate the significance of plasma ACTH, serum cortisol and UFC levels as well as ACTH stimulation test, aminoglutethimide test and insulin induced hypoglycemia test in patients with adrenal insufficiency. Sixteen patients with primary insufficiency (Addison`s disease) and 75 cases with secondary insufficiency (hypopituitarism) diagnosed from 1985 to 1999 were reviewed. It was found that high levels of ACTH were detected in all patients with primary insufficiency, and in most of them the levels of cortisol and UFC were low. No response of cortisol and UFC were observed after ACTH stimulation in the patients with primary insufficiency, but normal or delayed action was observed in the patients with secondary adrenal insufficiency. In most of secondary adrenal insufficiency the ACTH levels were in normal range but the cortisol and UFC levels were low; the elevated action of ACTH by insulin induced hypoglycemia test or aminoglutethimide test did not appear in the patients with secondary adrenal insufficiency. The results suggested that the low levels of cortisol and UFC were a common feature in the most of patients both with primary or secondary adrenal insufficiency. The ACTH level was the key indicator to distinguish the primary adrenal insufficiency from secondary adrenal insufficiency, as the ACTH levels were remarkably elevated in primary patients but were normal or decreased in secondary insufficiency patients. The ACTH stimulation test was useful in the diagnosis of the primary or secondary adrenal insufficiency. The insulin induced hypoglycemia test or aminoglutethimide test was valuable in the diagnosis of the secondary adrenal insufficiency.

THE CHARACTERISTICS OF PLASMA ACTH, SERUM CORTISOL AND UFC IN 136 PATIENTS WITH CUSHING SYNDROME / 解放军医学杂志

To evaluate the significance of plasma ACTH (pACTH), serum cortisol (SC) and urinary free cortisol UFC as well as low or high dose dexamethasone suppression test in Cushing syndrome, the levels of hormones were evaluated in 136 cases of Cushing syndrome. It was found that the levels of SC and UFC were elevated in almost all the 121 patients with Cushing syndrome. The mean levels of pACTH were higher in 86 patients with Cushing disease and lower in 36 cases with adrenocortical tumor or ACTH independent nodular adrenocortical hyperplasia (AINAH) than those in normal subjects. The ACTH levels might be in normal range in many patients with Cushing syndrome, but they were higher in patients with Cushing disease and lower in the patients with adrenocortical tumor or AINAH than those of the high limit at ACTH0am in normal subjects. It was a common feature that the diurnal rhythm of hormone secretion disappeared and the hormone levels were not suppressed by low dose dexamethasone suppression test in the patients with Cushing syndrome. In more than 90% of the patients with adrenocortical tumor or AINAH the levels of SC and UFC were not suppressed by high dose dexamethasone. In 12 of clinically cured patients with Cushing disease the levels of pACTH8am, SC8am and UFC were normal or even low. The pACTH levels were low in two patients with iatrogenic Cushing syndrome. The results suggested that examinations of SC, UFC and low dose dexamethasone suppression test were very important in the diagnosis of Cushing syndrome. The pACTH level was a key parameter to distinguish Cushing disease from adrenocortical tumor or AINAH.