About 40 years ago I had an older General Practitioner. I’m guessing he was born in the early 1900s.
Whenever we went to him he would always smell our breath and - sometimes - smell our urine.
Did they actually once teach this as a diagnostic tool or was this a quirk of his? What was he checking for?
I suspect he was checking for diabetes. That would fit well with smelling your breath–patients with diabetic ketoacidosis will be secreting some ketones through their lungs, leading to “fruity” breath.
As for smelling your urine–I suppose he could have been checking to see if it smelled sweet. I have heard that physicians at one point were actually taught to taste a patient’s urine if they suspected diabetes, as glucose would be secreted in the urine. I imagine smelling the urine instead would be a less distasteful, although less sensitive, method of checking the same thing.
Smelling the breath is actually still taught as a diagnostic tool, but as a sort of “in addition the patient may have ketotic breath” rather than as a “first smell the breath” kind of way.
You can have ketotic breath in diabetes, foetor hepaticus in liver disease and ureamic breath in kidney disease. Sometimes bad breath is caused by a sinus infection or a dental problem.
Urine usually smells foul if you are dehydrated or there is an infection present.
I don’t think you’d be able to smell sweetness from urine, because glycosuria isn’t usually that extreme, but I suppose you could try.
If you can’t afford to, or don’t want to run blood tests or dipstick the urine, I suppose you may as well use any cheap, easy diagnostic test at your disposal.