bayhorse, I aplogize. It's pure failure in my expression.
There are acid producing cell that break down bone. The process leaves a residue in the blood called CTX. The cells that build bone also leave a residue in the blood that we call P1NP.
High numbers of CTX in the blood mean that bone is being dissolved. High P1NP means that new bone is being laid down.
Some medications stop the acid emitting cells. We can see if they are working by measuring bone marker CTX. Other medications work by increasing the bone building cells and are tested by measuring P1NP.
https://www.youtube.com/watch?v=eYGkT6OrBk0
Antiresorptives work by blocking the acid emitting cells. Anabolics increase bone building cells.