In the main, bisphosphonates are not metabolized and are excreted unchanged in urine. There are concerns about using them in chronic kidney disease, end-stage renal disease and older people because of their potential nephrotoxicity and hypocalcaemic effects.
- Oral bisphosphonates are licensed for use in people with creatinine clearance (CrCl) as low as 30-35mL/min. There are data confirming that the effectiveness and safety of bisphosphonates, in women with osteoporosis, are not affected by impaired renal function (CKD 1-3); but this finding has not been confirmed in people with CKD stages 4 and 5 including those with ESRD or on dialysis.
- Cases of adynamic bone disease associated with bisphosphonate use have been reported in people with CKD stages 2-4. Until there are better data in these groups, oral bisphosphonates should be used with care to treat osteoporosis in people with CKD. A renal specialist should be consulted about using these agents in people with CKD stages 4 and 5 and, if used, their use should be reviewed if renal function deteriorates.
- Care is also needed in estimating GFR, by cross-checking MDRD or CKD-EPI estimates with the Cockcroft and Gault formula; particularly in people with CKD stage 3-5, so that renal function is not-overestimated. It is also important to recognise that people with CKD may also have elements of renal bone disease which will complicate management.