Associations of Changes in Bone Turnover Markers with Change in Bone Mineral Density in Kidney Transplant Patients
Hanne Skou Jørgensen, Kathleen Claes, Dieter Smout, Maarten Naesens, Dirk Kuypers, Patrick D’Haese, Etienne Cavalier, Pieter Evenepoel- Transplantation
- Nephrology
- Critical Care and Intensive Care Medicine
- Epidemiology
Background:
Bone loss after kidney transplantation is highly variable. We investigated whether changes in bone turnover markers associate with bone loss during the first post-transplant year.
Methods:
Bone mineral density was measured at 0 and 12 months, with biointact parathyroid hormone (PTH), bone specific alkaline phosphatase, intact pro-collagen type I N-terminal pro-peptide (PINP), and tartrate resistant acid phosphatase isoform 5b (TRAP5b) measured at 0, 3 and 12 months post-transplant (N=209). Paired transiliac bone biopsies were available in a subset (N=49). Between-group differences were evaluated by Student’s
Results:
Changes in bone mineral density varied from –22 to +17%/year. Compared to patients with no change (±2.5%/year), patients who gained bone mineral density had higher levels of PTH (236 vs 136 pg/mL), bone specific alkaline phosphatase (31.7 vs 18.8 μg/L) and Intact PINP (121.9 vs 70.4 μg/L) at time of transplantation, a greater decrease in bone specific alkaline phosphatase (-40 vs -21%) and Intact PINP (-43 vs -13%) by 3 months, and lower levels of Intact PINP (36.3 vs 60.0 μg/L) at 12 months post-transplant. Patients who lost bone mineral density had a less marked decrease, or even increase, in Intact PINP (+22 vs -13%) and TRAP5b (-27 vs -43%) at 3 months, and higher Intact PINP (83.7 vs 60.0 μg/L) and TRAP5b (3.89 vs 3.16 U/L) at 12 months compared to patients with no change. If none of the biomarkers decreased by the least significant change at 3 months, an almost 2-fold (69 vs 36%) higher occurrence of bone loss was seen at 12 months post-transplant.
Conclusions:
Bone loss after kidney transplantation was highly variable. Resolution of high bone turnover, as reflected by decreasing bone turnover markers, associated with bone mineral density gain, while increasing bone turnover markers associated with bone loss.