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Endocrinology
Published in Stephan Strobel, Lewis Spitz, Stephen D. Marks, Great Ormond Street Handbook of Paediatrics, 2019
Mehul Dattani, Catherine Peters
Adrenal and ectopic Cushing syndrome will not suppress with any dose of dexamethasone. Administration of CRH can be helpful in differentiating an adrenal and pituitary cause of the syndrome. Imaging of the pituitary and adrenals using MRI is usually indicated in order to locate the tumour, although the sensitivity is poor (70%). Inferior petrosal sinus sampling has a similar sensitivity and can be performed to locate a pituitary lesion and to lateralise a pituitary adenoma.
Selective Sampling of Petrosal Veins
Published in Demetrius Pertsemlidis, William B. Inabnet III, Michel Gagner, Endocrine Surgery, 2017
Justin R. Mascitelli, Aman B. Patel
Inferior petrosal sinus sampling (IPSS) was first reported in 1981 to differentiate CD and CS due to an ectopic ACTH-producing tumor [8]. IPSS with CRH stimulation is currently considered to be the gold standard in diagnosing CD when all other methods have failed, with sensitivity and specificity rates in the range of 96% and 100%, respectively [9]. Although IPSS was traditionally advocated for all cases with negative imaging [10], it is currently considered in selected cases with hypercortisolemia when both laboratory and radiographic tests fail to make the diagnosis with a high degree of certainty or in cases of persistent hypercortisolemia after hypophysectomy if not previously performed [11, 12]. In these cases, a preoperative positive MRI scan may have represented a nonsecreting pituitary adenoma.
Endocrine problems in pregnancy
Published in Philip E. Harris, Pierre-Marc G. Bouloux, Endocrinology in Clinical Practice, 2014
Diagnosis can be difficult in pregnancy, because normal reference ranges vary considerably. There are wide trimester-specific changes in urine free cortisol in pregnancy. An overnight dexamethasone suppression test is not reliable in pregnancy, and false-positive values may occur in pregnancy. The low-dose dexamethasone suppression test is the definitive diagnostic test for the syndrome. In the differential diagnosis of Cushing’s syndrome, one should consider that adrenal adenoma is responsible for 40%–50% in pregnancy compared with 15% outwith pregnancy. ACTH suppression, usually diagnostic of an adrenal cause outwith pregnancy, may be unsuppressed in half of pregnant mothers with a primary adrenal cause. The high-dose dexamethasone suppression test has increased utility in pregnancy. Magnetic resonance imaging (MRI) of the adrenal or pituitary will be performed depending on results.66 Inferior petrosal sinus sampling is safe and useful in pregnancy when indicated.
Acute severe Cushing’s disease presenting as a hypercoagulable state
Published in Baylor University Medical Center Proceedings, 2021
Maria Mohammed Fariduddin, Wajihuddin Syed, Vidita Divan, Prashant Nadkarni, Ruban Dhaliwal
Approximately 40% of patients with CD have no visible tumor on standard MRI of the brain,12 as 90% to 95% of these tumors are microadenomas. Excessive ACTH production is followed by the loss of ACTH circadian rhythm, becoming independent of hypothalamic regulation and resistant to glucocorticoid feedback inhibition,13 causing adrenal hyperplasia and subsequent loss of circadian rhythm in cortisol secretion as well.14 The pituitary functions as if its threshold for glucocorticoid feedback inhibition is raised. Therefore, in most cases, there will be a positive response to high levels of glucocorticoids, defined by suppression of cortisol to <50% of the basal value. At other times, this response can be blunted15 and these intermediate values are not helpful in distinguishing a pituitary and ectopic source of ACTH. Adequate cortisol suppression was observed with high-dose DST in our patient. An unremarkable pituitary MRI added to the clinical dilemma. Corticotropin-releasing hormone stimulation and bilateral inferior petrosal sinus sampling confirmed the diagnosis of pituitary CD.
Severe ectopic Cushing’s syndrome
Published in Baylor University Medical Center Proceedings, 2020
Ankur Modi, Jamie Olejarski, Ashley Windham
Hypercortisolism must first be confirmed followed by a differentiation between an ACTH-dependent and -independent CS. In cases of CS with elevated ACTH levels, Cushing’s disease must be differentiated from EAS.2 Inferior petrosal sinus sampling is the most sensitive test for this purpose. It is the next step in evaluating ACTH-dependent CS when magnetic resonance imaging does not reveal a definite adenoma.3 A high-dose dexamethasone suppression test has limitations given that cortisol suppression is not present in 10% to 20% of patients with ACTH-secreting pituitary gland adenomas. Once EAS is diagnosed, visualization studies are required, usually with computed tomography of the neck, chest, abdomen, and pelvis; however, tumors are not identified in 19% of patients.4
Sensitivity of Different ACTH and Cortisol Concentration Values in Corticotropin-Releasing Hormone Based Tests in Cushing’s Disease
Published in Endocrine Research, 2023
Shehrban Sobeh Khalil, Mohammad Sheikh Ahmad, Talia Sarah-Hefer, Ekaterina Yovanovich, Maria Reut, Limor Chen-Konak, Nariman Saba-Khazen, Leonard Saiegh
Since distinction between pituitary and ectopic source of ACTH secretion is critical, and since imaging modalities are usually unsatisfactory for that distinction, reliable biochemical diagnostic criteria are mandatory.10 The gold standard test for the diagnosis is bilateral inferior petrosal sinus sampling (BIPSS), but it requires high technical experience and may involve complications. Moreover, BIPSS positive predictive value for diagnosing CD is about 99%, while its negative predictive value is only 20%.11