This is very interesting and something new for me.

I found this study that posits a portential reason for this:
https://smw.ch/index.php/smw/article/download/1876/2634
“ Mild secondary hyperparathyroidism after infusion of zoledronic acid is often observed, possibly as a compensatory mechanism to maintain normocalcaemia [25, 26], and most patients do not become overtly hypocalcaemic. This increase in parathyroid hormone prevents hypocalcaemia by renal reabsorption of calcium, increased vitamin D production, and stimulation of osteoclasts to resorb bone [24].”

Interested to see if others who have experienced this chime in.