The Fifth Commandment forbids also the use of violence against one's own body. Jesus expressly demands that we accept and love ourselves: "You shall love your neighbor as yourself" (Mt 22:39). Self-destructive acts against one's own body ("body piercings", cutting and so on) are in most cases psychological reactions to experiences of abandonment and a lack of love; hence they call first and foremost for our sincere and loving response. Within the context of organ donation, it must be made clear, however, that there is no human right to destroy one's own God-given body.
(Catholic Youth Catechism, question 387)