@anewyorker my creatinine-based eGFR dipped from 55 to 36 last fall. I had stopped Tymlos some time before. Now that it is tested more often, it really bounces around and is generally mid to high 40's. My GFR from Cystatin C has stayed stable in the low 50's. Nephrologist says the true value is probably somewhere in between.

I have low blood pressure which can throw off the creatinine based GFR, but I have always had low blood pressure. The kidney doctor checked for a cyst or infection in kidneys, did an echocardiogram (low heart function can also affect it) and basically theorized it might be my muscle mass loss. I also have lupus and high antibodies for scleroderma so damage from those was checked.

My kidneys were fine throughout my 2 years on Tymlos. I am only one person and we are all different so just sharing my experience. I still don't really know why mine dropped! I have been told to increase salt (low bp) and protein (muscles) which is the opposite of the usual kidney diet. Hope you can see a nephrologist! ps I have an L1 fracture too (and L2, L5, T12, T6, T4!) Having fractures may cause muscle loss since we don't lift and exercise as before!