Treason(1978)

Orson Scott Card

Lanik Mueller's birthright as heir to planet Treason's most powerful rulership will never be realized. He is a "rad" -- radical regenerative. A freak among people who can regenerate injured flesh... and trade extra body parts to the Offworld oppressors for iron. For, on a planet without hard metals -- or the means of escape -- iron is power in the race to build a spacecraft.
Iron is the promise of freedom -- which may never be fulfilled as Lanik uncovers a treacherous conspiracy beyond his imagination.
Now charged with a mission of conquest -- and exile -- Lanik devises a bold and dangerous plan... a quest that may finally break the vicious chain of rivalry and bloodshed that enslaves the people of Treason as the Offworld never could.