did you dose anything to get it that high. If not, i would retest with another kit. If it is that high, normal waterchanges should help get it down to where it needs to be. If this number is surprising to you, i would first question the method in which you got it. It would be very surprising to me that any tank would maintain levels that high that were not artificially introduced.
I had a calcium spike to 500+ because i left my doser running all day and night. Within a week or 2 it was back down to normal with no action taken other than stopping the doser.