This brings up another question I have, which I should probably include elsewhere, but how many people share scores with others? I feel uncomfortable doing so, so at this point my husband and I have decided to just share that he's gifted with others. I just don't want the number to follow him if that makes any sense at all.
Who needs to know?
School district, yes, if there are programs this will qualify him for. You could use the score for DYS or another talent search, or to justify his placement in an above-grade extracurricular (though I wouldn't rely on their understanding of what an IQ score means).
Otherwise, we never used the word "gifted" with our 6 year olds, and certainly not with friends or neighbors. It alienates people and makes them think you are comparing your child to others.
Later we gradually gave our kids more context and appropriate words for understanding their own brains and their own challenges in school, but we did not give them their IQ scores. Likely to do more harm than good, in our opinion, since our children are not tactful. We will revisit this decision as they grow older.
We have selected family members (literally two) who know the whole story, because they really get it. We have a few friends who are our allies in advocacy-- they know too. Otherwise, this topic remains private information, like any school test score.