Other animals do it, although I'm not asserting that as a basis for advocation - we have an expression in English: don't knock it 'til you've tried...
Of course, we know that the kidneys are the pathway for water-soluble toxins, as the liver/intestine is for fat-soluble toxins.
Paradoxically, according to the principles of hormesis and homeopathy, I found urine therapy invaluable during the bulk of my detoxification after withdrawing from a cooked diet. I had multiple instances of herxheimer effect following consumption of 100% urine and multiple dilutions of urine (according to homeopathy dilution practices).
I no longer consume my own urine on RAF, although I would consider it as a means to an end to either invoke or assist during a healing crisis.
Shivambu shastra is an old tradition, possibly mimicked by humans that observed animals (like ingesting these mineral pitches like shilajit/moomiyo).
I won't necessarily talk about components of "plasma ultrafiltrate" like urokinase (a de-fibrinolytic enzyme) that are used as fractions in every day life (surgery, cosmetics).
The information overload continues...