Ahumada-del Castillo syndrome /ä′ho̅o̅mä″dädel′kästē″- yō/ [Juan Carlos Ahumada, 1890–1976, Argentine gynecologist; Enrique B. del Castillo, 1897–1969, Argentine physician and endocrinologist] , a form of secondary amenorrhea that may be associated with a pituitary gland tumor. It is characterized by both galactorrhea and amenorrhea, with low gonadotropin secretion, in the absence of a pregnancy.