Mechanism, diagnosis, and treatment of cyclic Cushing’s syndrome: A review

Cushing's syndrome (CS) is caused by hypercortisolemia, leading to the occurrence of characteristic clinical symptoms. A small number of patients with CS have periodic and intermittent increases in cortisol levels, resulting in recurrent episodes of clinical symptoms. Such patients are known as having cyclic CS (CCS). The cortisol secretion cycle of patients with CCS is unpredictable, and laboratory tests often show negative results during the normal cortisol secretion period; therefore, the diagnosis and treatment of the disease are currently difficult. Although the pathogenesis of CCS remains uncertain, recent studies have suggested that it may be closely related to hypothalamic factors, feedback mechanisms, and tumor infarction. Our review summarizes the current state of research on the potential mechanisms, diagnosis, and treatment of CS and provides an outlook for future studies.