Cat craving salt

My daughter asked me to post about one of her cats, a shelter graduate going on four years old. His kidney numbers recently came back very slightly elevated. (She's put him on prescription food). She notices that he is very attracted to her contact (saline) solution, and tries to lick the little packets. (I assume it's not poisonous, since it's designed to go in the eye). But could there be a connection between kidney problems and salt craving? Personally I don't think salt craving is too unusual. My cats like to lick sweat, for example. Thanks.

I don't know if there is any connection in terms of a craving for salt as a result of kidney issues, but if a cat seeks out salt and regularly accessed it I guess it could contribute to kidney problems.  Hopefuly others with more experience of this will offer advice.