|Classification and external resources|
Nelson's syndrome is the rapid enlargement of a pre-existing ACTH-secreting pituitary adenoma that occurs after the removal of both adrenal glands because of the lack of the negative feedback of cortisol on the production of ACTH.
Signs and symptoms
The common signs and symptoms include muscle weakness and skin hyperpigmentation due to excess MSH. Nelson's syndrome is now rare because bilateral adrenalectomy is now only used in extreme circumstances.
Removal of both adrenal glands, or bilateral adrenalectomy, is an operation for Cushing's syndrome. Removal of both adrenals eliminates production of cortisol, and the lack of cortisol's negative feedback can allow any pre-existing pituitary adenoma producing ACTH to grow unchecked. Continued growth can cause mass effects due to physical compression of brain tissue, along with increased production of adrenocorticotrophic hormone (ACTH) and melanocyte stimulating hormone (MSH). The accompanying increase in MSH is due to ACTH and MSH being derived from a common precursor peptide, known as proopiomelanocortin (POMC).
A brain MRI is typically performed to locate a pituitary microadenoma. In combination with positive MRI findings, a high plasma ACTH level is diagnostic.
Pituitary surgery is performed in some cases. The risk can also be minimized by pituitary irradiation.
The condition is named for the American endocrinologist Dr Don Nelson, who first reported on the phenomenon in 1960.
- Biller BM, Grossman AB, Stewart PM, et al. (July 2008). "Treatment of adrenocorticotropin-dependent Cushing's syndrome: a consensus statement". J. Clin. Endocrinol. Metab. 93 (7): 2454–62. doi:10.1210/jc.2007-2734. PMC 3214276. PMID 18413427.
- Kelly PA, Samandouras G, Grossman AB, Afshar F, Besser GM, Jenkins PJ (December 2002). "Neurosurgical treatment of Nelson's syndrome". J. Clin. Endocrinol. Metab. 87 (12): 5465–9. doi:10.1210/jc.2002-020299. PMID 12466338.
- Nelson D, Meakin J, Thorn G (1960). "ACTH-producing pituitary tumors following adrenalectomy for Cushing's syndrome". Ann Intern Med 52: 560–9. doi:10.7326/0003-4819-52-3-560. PMID 14426442.