I had a discussion about this with a doctor. I asked them for their opinions on sodium to potassium ratios by age group and sodium loss through sweat. I got blank stares and the subject changed. I've had far more fascinating and informative discussions with nutritionists and fitness coaches, not to suggest they are a definitive source of knowledge. I find it ultimately best to research things on my own and take all scientific papers with a skeptical grain of salt.
A physician probably learns the physiology of sweat glands, mechanisms for how the human body regulates sodium and potassium, and diseases caused by regulatory mechanisms not working. Unless they had an interest or read a study, I’m not sure I would expect a physician to know that, and in my experience a lot of physicians are reluctant to speculate.
Nutritionists and fitness coaches are much more willing to speculate in my experience, with the caveat that they may not have the same education as a scientist as a physician does.
To be fair, an expert not answering a question that they don't know the answer to is a good outcome. The real expert for your question would be a researcher in the specific field, or perhaps the rare doctor who has taken an interest in following such research.
