Cushing's syndrome with a paradoxical response to dexamethasone

Tumor Shrinkage by Metyrapone in Cushing Disease Exhibiting Glucocorticoid-Induced Positive Feedback

Context

Paradoxical increases in serum cortisol in the dexamethasone suppression test (DST) have been rarely observed in Cushing disease (CD). Its pathophysiology and prevalence remain unclear.

Case Description

A 62-year-old woman with suspected CD showed paradoxical increases in cortisol after both 1-mg and 8-mg DST (1.95-fold and 2.52-fold, respectively). The initiation of metyrapone paradoxically decreased plasma adrenocorticotropic hormone (ACTH) levels and suppressed cortisol levels. Moreover, the pituitary tumor considerably shrank during metyrapone treatment.

Ex Vivo Experiments

The resected tumor tissue was enzymatically digested, dispersed, and embedded into Matrigel as 3D cultured cells. ACTH levels in the media were measured. In this tumor culture, ACTH levels increased 1.3-fold after dexamethasone treatment (P < 0.01) while control tumor cultures exhibited no increase in ACTH levels, but rather a 20% to 40% suppression (P < 0.05).

Clinical Study

A cross-sectional, retrospective, multicenter study that included 92 patients with CD who underwent both low-dose and high-dose DST from 2014 to 2020 was performed. Eight cases (8.7%) showed an increase in serum cortisol after both low-dose and high-dose DST.

Conclusion

This is the first report of a patient with glucocorticoid (GC)-driven positive feedback CD who showed both ACTH suppression and tumor shrinkage by metyrapone. Our cohort study revealed that 8.7% of patients with CD patients possibly possess GC-driven positive-feedback systems, thereby suggesting the presence of a new subtype of CD that is different from the majority of CD cases. The mechanisms exhibiting GC positive feedback in CD and the therapeutic approach for these patients remain to be investigated.

Paradoxical and bidirectional drug effects

A paradoxical drug reaction constitutes an outcome that is opposite from the outcome that would be expected from the drug's known actions. There are three types: 1. A paradoxical response in a condition for which the drug is being explicitly prescribed. 2. Paradoxical precipitation of a condition for which the drug is indicated, when the drug is being used for an alternative indication. 3. Effects that are paradoxical in relation to an aspect of the pharmacology of the drug but unrelated to the usual indication. In bidirectional drug reactions, a drug may produce opposite effects, either in the same or different individuals, the effects usually being different from the expected beneficial effect. Paradoxical and bidirectional drug effects can sometimes be harnessed for benefit; some may be adverse. Such reactions arise in a wide variety of drug classes. Some are common; others are reported in single case reports. Paradoxical effects are often adverse, since they are opposite the direction of the expected effect. They may complicate the assessment of adverse drug reactions, pharmacovigilance, and clinical management. Bidirectional effects may be clinically useful or adverse. From a clinical toxicological perspective, altered pharmacokinetics or pharmacodynamics in overdose may exacerbate paradoxical and bidirectional effects. Certain antidotes have paradoxical attributes, complicating management. Apparent clinical paradoxical or bidirectional effects and reactions ensue when conflicts arise at different levels in self-regulating biological systems, as complexity increases from subcellular components, such as receptors, to cells, tissues, organs, and the whole individual. These may be incompletely understood. Mechanisms of such effects include different actions at the same receptor, owing to changes with time and downstream effects; stereochemical effects; multiple receptor targets with or without associated temporal effects; antibody-mediated reactions; three-dimensional architectural constraints; pharmacokinetic competing compartment effects; disruption and non-linear effects in oscillating systems, systemic overcompensation, and other higher-level feedback mechanisms and feedback response loops at multiple levels. Here we review and provide a compendium of multiple class effects and individual reactions, relevant mechanisms, and specific clinical toxicological considerations of antibiotics, immune modulators, antineoplastic drugs, and cardiovascular, CNS, dermal, endocrine, musculoskeletal, gastrointestinal, haematological, respiratory, and psychotropic agents.

The prevalence and characteristic features of cyclicity and variability in Cushing's disease

OBJECTIVE

Cyclical Cushing's syndrome may render the diagnosis and management of Cushing's disease difficult. The aim of the present study was to investigate the prevalence of cyclicity and variability in patients with Cushing's disease, and to identify putative distinctive features.

DESIGN

Retrospective case-note study.

METHODS

We analysed the case records of 201 patients with Cushing's disease in a retrospective case-note study. Cyclicity was considered as the presence of at least one cycle, defined as a clinical and/or biochemical hypercortisolaemic peak followed by clinical and biochemical remission, followed by a new clinical and/or biochemical hypercortisolaemic peak. The fluctuations of mean serum cortisol levels, as assessed by a 5-point cortisol day curve, defined the variability.

RESULTS

Thirty (14.9%; 26 females) patients had evidence of cyclicity/variability. 'Cycling' patients were older but no difference in sex or paediatric distribution was revealed between 'cycling' and 'non-cycling' patients. The median number of cycles was two for each patient, and 4 years was the median intercyclic period. A trend to lower cure rate post-neurosurgery and lower adenoma identification was observed in 'cycling' compared with 'non-cycling' patients. In multivariate analysis, older patients, longer follow-up, female sex and no histological identification of the adenoma were associated with an increased risk of cyclic disease.

CONCLUSIONS

This large population study reveals that cyclicity/variability is not an infrequent phenomenon in patients with Cushing's disease, with a minimum prevalence of 15%. Physicians should be alert since it can lead to frequent problems in diagnosis and management, and no specific features can be used as markers.

Ectopic Cushing's syndrome with periodic hormonogenesis--a case suggesting a pathogenetic mechanism

We report on a case of ectopic Cushing's syndrome due to a thymic carcinoid tumour with periodic hormonogenesis. Periods of hormonal production averaged 27 days. Prior to bilateral adrenalectomy, mean (s.d) values of ACTH and cortisol were 202.1 (50.3) pg/ml and 46 (14.7) micrograms/dl, ACTH rising to 3996 +/- 425 pg/ml (P less than 0.01) and cortisol falling to 6.3 +/- 1.5 micrograms/dl (P less than 0.01) in the immediate postoperative period. During the late postoperative period (2-13 months following surgery) ACTH levels fell to 509.3 (123.8) pg/ml (P less than 0.01), but remaining even higher (P less than 0.01) than before adrenalectomy. The pattern of ACTH in the present case suggests the existence of a negative feedback exerted by the cortisol over tumoral ACTH.

Occult Cushing's disease presenting with acute psychosis

A 37-year-old woman presented with acute psychosis and cognitive impairment. Skull x-ray showed an enlarged sella turcica with erosion of the floor. Endocrinologic workup suggested the diagnosis of Cushing's disease and hyperprolactinemia. She had no cushingoid feature, and the only physical sign was mild generalized obesity. She showed a paradoxic response to dexamethasone suppression, and underwent trans-sphenoidal resection of a pituitary macroadenoma. Electron microscopy showed the tumor to be a Crooke's cell adenoma. Results of immunohistochemical staining were positive only for ACTH and beta-endorphin. The neuropsychiatric manifestations resolved after surgery.

Regulation of ACTH and cortisol in depression

Disturbances of hypothalamic-pituitary-adrenal regulation are frequently observed in a subgroup of patients suffering from major depression. The mechanism of hypothesized pituitary and hypothalamic involvement in this dysregulation remains relatively uncharacterized. In this paper we investigated the response of adrenocorticotropin (ACTH), as well as cortisol, to dexamethasone inhibition and characterized the dynamic response of ACTH to a one-hour infusion of cortisol in normal subjects and patients suffering from depression. A paradoxical increase in ACTH in response to cortisol is noted in one patient.

Remission of Cushing's syndrome during pregnancy

We present the first report of pregnancy with Cushing's syndrome due to an adrenal cortical adenoma, in which the hypercortisolemia disappeared during the third trimester of pregnancy, but recurred following the delivery of a normal male infant at 38 weeks by Cesarean section. The case is also unique because plasma ACTH levels were elevated during gestation and postpartum. Also, urinary estriol excretion was very low during the third trimester of pregnancy. The relationship of Cushing's syndrome and pregnancy are reviewed. This study points up some of the limitations of the routinely used dynamic tests of pituitary-adrenal function in Cushing's syndrome, and emphasizes the importance of various radiologic procedures in evaluation of patients with Cushing's syndrome.

Paradoxical ACTH response to glucocorticoids in Cushing's disease

To define further the defect in the steroid feedback mechanism in Cushing's disease, we studied the acute effects of intravenous administration of glucorticoids on plasma ACTH levels in seven patients with this disease after total adrenalectomy. In seven other patients with hypoadrenocorticism ACTH was readily suppressed; a significant decrease (72.5+/-5 per cent, mean +/- S.E.M., P less than 0.002) occurred within 15 minutes of the start of an infusion of 50 mg per hour of cortisol. In contrast, in the seven adrenalectomized patients with Cushing's disease, cortisol induced a transient paradoxical rise in ACTH levels, with a maximum at 15 minutes (347+/-99 per cent,, P less than 0.05). A similar ACTH response was observed with dexamethasone. Cushing's disease is characterized by a paradoxical transient rise in ACTH after glucocorticoid administration. This effect was more pronounced in adrenalectomized than in nonadrenalectomized patients.

An evaluation of laboratory tests for the detection and differential diagnosis of Cushing's syndrome

1. Results of tests for the diagnosis of Cushings syndrome of varoius aetiologies are discussed for twenty-five patients in whom the pathology was established by operation or autopsy. 2. Control values for the urinary excretion of free cortisol, 17-OHCS, Porter-Silber chromogens (P-SC) and 17-OS and plasma levels of P-SC are compared with those for normal subjects. 3. The results indicated that urinary values are within the normal range for some patients with Cushing's syndrome. 4. Plasma levels of P-SC in the morning were within the normal range for the majority and elevated for the rest. 5. Some patients showed day-night variation of plasma P-SC but evening values were above the normal range. 6. The expected response for low dosage dexamethasone was found in all patients tested but unexpected responses followed high dosage in some. 7. Plasma 11-OHCS in the five patients tested failed to respond to insulin induced hypoglycaemia. 8. Metyrapone administration and corticotrophin infusion tests had limited usefulness in establishing the aetiology of the disease. The 17-OHCS excretion became raised in the response to corticotrophin and the evaluation was prolonged beyond normal responsiveness.

Cyproheptadine-induced remission of Cushing's disease

Experimental evidence suggests a central-nervous-system origin of Cushing's disease and a role for serotonin in the regulation of ACTH release. The efficacy of cyproheptadine therapy, therefore, was studied in three patients with such disease. Administration of 24 mg daily over a period of three to six months was associated with prompt and sustained clinical and laboratory remission. Lessening of the physical manifestations of hypercorticism occurred, together with marked improvement in muscular weakness. Urinary corticosteroid excretion and cortisol secretory rate returned to normal. The urinary corticosteroid response to dexamethasone (2 mg per day) became normal; a paradoxical increase followed 8 mg per day. Abnormal circadian periodicity of plasma cortisol concentrations persisted. Return of normal amounts of Stage III to IV sleep occurred in the one patient so studied, who previously had markedly decreased periods of these stages. Discontinuance of therapy in one patient was associated with return of laboratory evidence of hypercorticism.

Anomalous responses to stimulation and suppression tests in Cushing's syndrome due to a calcified adrenal adenoma

A case of Cushing's syndrome, due to an adrenal adenoma, which responded to dexamethasone with a rise in plasma urinary steroids is described. Further unusual features were radiologically visible calcification and a response to ACTH stimulation.