impeller radial load

When calculating the radial load on a single stage centrifugal pump is the discharge pressure taken as just the differential pressure. For example, I am stuffing the pump with 500 ft and developing 100 ft with the pump....totoal discharge 600 ft.

Do I use 100 ft for calculating the radial load or 600 ft. I can't find anything written on the subject.

Thanks

I am a little confused.

Is the output 600' above the pump or 100' above the pump?

Or is the outlet at the pump and you are just trying for volume or xxx-psi at the outlet?

Is the outlet restricted as in a hose nozzle etc?