I did CMIA hiv test it showed 0.54 index value they told non-reactive, but why I am seeing 0.5 please explain me the reason?

It is normal. So non reactive. Donot worry.

A non-reactive result means that no HIV antibodies were found. This would find any exposures which happened 6 weeks prior to test or before that. A non-reactive test does not mean that a person is immune to HIV in the future, only that they do not show the virus in their body at the time of the test. Index values are nothing to worry about. Index values fluctuate up and down every day, just like blood pressure or hormone levels, and do not indicate your HIV status. The only thing you need to be concerned about are the actual results -- i.e. Reactive or non-reactive. Non-reactive means negative, and a negative result is what you're looking for.