Cushing’s disease occurs when the pituitary gland has increased secretion of adrenocorticotropic hormone (ACTH), which can be related to any one of several causes (Feelders & Hofland, 2013). One of the most common is the presence of an adenoma on the pituitary. There are many clinical signs of Cushing’s disease, although these are not always found in all patients. These include high blood pressure, excess hair growth in women, red stretch marks, poor concentration, having a red face, and changes to short-term memory (Petersenn et al., 2015). Patients may also have acne, weak bones, and bruise easily. Diagnosis of the disease is generally done through laboratory testing, including salivary and blood serum cortisol testing, as well as urinary testing (Petersenn et al., 2015). As the signs and symptoms vary greatly between patients, multiple tests are recommended meaning that there are no conclusive clinical signs.
Cushing’s disease has the main symptom of Cushing’s syndrome, which affects the cortisol system of the endocrine system. In healthy patients, the paraventricular nucleus in the hypothalamus releases corticotropic-releasing hormone, which in turn stimulates the pituitary to release ACTH (Petersenn et al., 2015). ACTH then enters the blood stream, where it stimulates the release of cortisol (Pivonello et al., 2015). In patients with Cushing’s, this system is disrupted at any one of these points. Cushing’s occurs when there is an excess production of any one of these three compounds, which leads to the eventual overproduction of cortisol, which explains why we test for cortisol in saliva and urine as a detection method (Pivonello et al., 2015). If the adenoma in the adrenal gland is causing an increased amount of blood cortisol, this causes the feedback system to signal to the pituitary gland to reduce the synthesis of ACTH, which means that there are reduced levels of ACTH in some of Cushing’s syndrome (Pivonello et al., 2015). Cushing’s disease itself, however, refers exclusively to the excess production of ACTH (Pivonello et al., 2015).

References
• Feelders, R. A., & Hofland, L. J. (2013). Medical treatment of Cushing’s disease. The Journal of Clinical Endocrinology & Metabolism, 98(2), 425–438.
• Petersenn, S., Beckers, A., Ferone, D., Van Der Lely, A., Bollerslev, J., Boscaro, M., … others. (2015). THERAPY OF ENDOCRINE DISEASE: Outcomes in patients with Cushing’s disease undergoing transsphenoidal surgery: systematic review assessing criteria used to define remission and recurrence. European Journal of Endocrinology, 172(6), R227–R239.
• Pivonello, R., De Leo, M., Cozzolino, A., & Colao, A. (2015). The treatment of Cushing’s disease. Endocrine Reviews, 36(4), 385–486.