From the Guidelines
In patients with Cushing's syndrome versus adrenal disorders, DHEAS levels are typically normal or low, and norepinephrine levels are generally normal, unless there is a concurrent pheochromocytoma, as evidenced by recent guidelines 1. When testing for Cushing's versus adrenal disorders, it is essential to consider the specific condition and the underlying pathophysiology.
- In Cushing's syndrome, DHEAS levels are typically normal or low, not high, as cortisol excess suppresses ACTH and subsequently DHEAS production.
- Norepinephrine levels are generally normal in Cushing's syndrome unless there is concurrent pheochromocytoma. In contrast, certain adrenal disorders like adrenal adenomas or carcinomas may produce elevated DHEAS, particularly if they are androgen-secreting tumors.
- Pheochromocytomas, which are catecholamine-producing adrenal tumors, cause elevated norepinephrine levels. The diagnostic approach should include a comprehensive panel including 24-hour urinary free cortisol, overnight dexamethasone suppression test, and midnight salivary cortisol for Cushing's, while plasma or urinary metanephrines and catecholamines are used to diagnose pheochromocytoma, as recommended by recent consensus guidelines 1. These tests help differentiate between various adrenal pathologies and guide appropriate treatment, ultimately improving patient outcomes in terms of morbidity, mortality, and quality of life.
From the Research
Diagnostic Tests for Cushing's Syndrome
- The diagnosis of Cushing's syndrome involves a complex diagnostic assessment, and several studies have suggested that the prevalence of Cushing's syndrome is higher than previously thought 2, 3, 4.
- The recommended diagnostic tests for Cushing's syndrome include 24-h urinary free cortisol, 1-mg overnight dexamethasone suppression test, and late-night salivary cortisol 2, 3, 4.
- Once the diagnosis of Cushing's syndrome is established, the next step is the measurement of plasma ACTH to differentiate between ACTH-dependent and ACTH-independent causes 2, 4.
DHEAS and Norepinephrine Levels
- There is no direct evidence in the provided studies to suggest that DHEAS and norepinephrine levels would be high in patients with Cushing's syndrome versus adrenal disorders.
- However, it is known that Cushing's syndrome is associated with supraphysiological exposure to glucocorticoids, which can affect the levels of various hormones and biomarkers, including DHEAS and norepinephrine 4.
- Further studies would be needed to determine the specific effects of Cushing's syndrome on DHEAS and norepinephrine levels and to differentiate between Cushing's syndrome and adrenal disorders.
Diagnostic Challenges
- The diagnosis of Cushing's syndrome can be challenging due to the resemblance of its clinical features with those of common diseases found in the general population 2, 3, 4.
- The choice of test, the modality of specimen collection, and the quality of measurement are key factors for optimal care of patients with suspected Cushing's syndrome 2.
- The use of combined diagnostic tests, such as the 1-mg dexamethasone suppression test and 24-hour urinary free cortisol excretion, can help improve the accuracy of diagnosis 3, 5.