If waste products were pure waste products, the human body would simply not work. We would not be here if that nonsense were true.
Example: I learned in Biochemistry that uric acid is simply a waste product of purine metabolism and if uric acid concentration reaches too high a concentration in the bloodstream it causes gout in selected synovial joints.
I wondered at the time, why not ALL synovial joints? Why not a whole lot of trauma in the bloodstream?
Really? Then why do the kidneys reabsorb on average about 80% of the uric acid in the glomerular filtrate? The body is telling us that uric acid is not a pure waste product, but in fact something quite useful, but we do not listen to the body. We know better. Sure we do – we are the hollow men, headpiece stuffed with straw.
Re: causing gout. Really? Then why do people with ordinary, everyday levels of uric acid get gout? Why do people with extraordinarily high levels of uric acid rarely get gout? And why does gout typically present first as an inflamed synovial joint of just one of the big toes? Clearly, we would expect the first presentation of gout to be all synovial joints and we would expect a good deal of trauma in the entire blood stream, if extremely high uric acid concentration in the bloodstream drives gout.
Further: if high serum uric acid is secondary to poor kidney function or chronic deficiency in vitamin C, that is a bad sign clinically. If high serum uric acid is merely a sign of a seafood-rich diet (a lot of herring for example), it most certainly is not a bad clinical sign. If gout has already occurred, then indeed some people will find some pain relief by taking allopurinol. So what? All that shows is what I have said before:
High uric acid does not cause gout, but it can aggravate gout.
This statement has two qualifications for those who did not notice it: can & aggravate, meaning that it does not necessarily aggravate gout, but can aggravate gout in some but certainly not all individuals with gout.