Hydration tests are available to estimate sweat electrolyte loss, but require independent data validation.

“you can also use any number of hydration tests I know that there is some coming out in the market very very soon that can give you theoretically real time um measurements just like a CGM would be although I haven't seen any data on if those are accurate or not I haven't used one yet but there are number that are out super cheap you know 10 15 20 bucks all the way up to a couple hundred dollars you can buy these patches put them on you and get a reasonably close estimate um and again if those things are five or 10 or 20% off I don't know have to see independent data come out first”