The invention relates to a method for detecting endothelin in body fluids, which comprises the following steps: a) addition of a known amount of labelled endothelin to the endothelin-containing body fluid b) binding of the endothelin to an insoluble trap c) by removal of the trap from the body fluid d) releasing the endothelin from the trap and removing the trap e) conventional detection of the endothelin and correction of the measurement with the aid of the recovered labelled endothelin.
