According to Andy Cutler's hair test theory the test seems to have the look of his Rule 1. This is where most essential elements are low or low normal and toxic elements are usually low as well. As you can imagine, the levels of toxic elements are not usually very useful. We tend to assume those levels don't accurately reflect body levels.
A mature version of the rules along with discussions of all of the toxic and essential elements are in his hair test book. I think there is a set of rules for ARL tests in the back of his book. I don't have them memorized! nomalgam.com
Off the charts Ni on a Rule 1 test is very unusual. I'd want to do followup blood or other tests and check for symptoms of Ni and ongoing exposure. Also you might consider possible contamination of the hair sample.
Typically when a test matches a rule and symptoms match mercury, the person gets all Amalgam removed and does some trial rounds of chelation with DMSA or maybe DMPS. Those who have an Hg problem typically react somewhat to taking an Hg chelator. This is a further indicator.
There are other tests that are sometimes done--urine porphyrins and provoked urine tests; however the latter can be dangerous. There are plenty of bad stories about them. Cutler discourages their use especially if Amalgam is present. My porphyrins, provoked urine and hair test did not look bad, yet 2+ years of chelation have been life changing. //www.curezone.org/forums/fm.asp?i=1951581
Testing for heavy metals stinks--short of an autopsy!