They should be taking into account the PTH "triangle" of PTH, Ca, PO4 and to a lesser extent K. It's a balance between your PTH levels and Calcium and Phosphates - too high PTH and Calcium/Phos can be leached from the bones (secondaryhyperparathyroidism leading to bone disease) so say your PTH lowers, you still need to check the impact on those other levels that they are balanced out OK. Sensipar tends to lower serium Ca levels in the blood (and as a bonus side effect, cholesterol too
) which is also something to be aware of.
Really though nephs would be monitoring those values on a regular basis anyway since it's the basic FBE that they need to ensure is in range anyway.