A valve assembly 2 for adjusting the flow of bodily fluid from one part of a human body to another, the valve assembly 2 comprising:- a body portion 7, 9 having a flow inlet 14 and a flow outlet 18 a valve located in a flow path from the inlet to the outlet, the valve comprising a valve seat 22 and a closing element 20, the closing element 20 being adapted to seal against the valve seat 22 and a carrier element 4 mounted within the body portion 7, 9, having a plurality of pockets 76a to h, each pocket 76a to h housing a respective preload element 5a to 5h, each preload element 5a to h being of a different weight from that of the other preload elements, the carrier element 4 being moveable relative to the body portion 7, 9, so as to align a preload element 5e of a desired weight with the closing element 20, the self weight of the chosen preload element 5e applying preload to the closing element 20 dependent on the orientation of the valve assembly 2.
