Trends of bone mineral density and bone quality in a paediatric kidney transplant recipient: A case report.

Kidney transplant (KT) requires long-term glucocorticoid (GC) treatment against acute and/or chronic rejection. Glucocorticoid-induced osteoporosis (GIOP) is one of the major concerns in kidney transplant recipients (KTRs). Therefore, it is essential to accumulate GIOP data from paediatric KTRs to aid in their healthy growth. A serial observational study of bone strength was carried out in an 8-year-old girl with bilateral hypoplastic kidney who underwent ABO-compatible living-donor KT and GC treatment over 2 years. Bone strength was evaluated by bone mineral density (BMD) and serum bone turnover markers (BTMs), including serum alkaline phosphatase (S-ALP), serum tartrate-resistant acid phosphatase 5b (S-TRACP-5b), and serum undercarboxylated osteocalcin (S-ucOC). All the levels of BTMs and BMD from 1 M to 4 M remained lower than the levels at 0 months (0 M: baseline). After gradual reduction of GC dose (4 M-24 M), S-ALP levels increased from baseline and S-TRACP-5b levels remained lower than the baseline level, but BMD recovered to baseline and increased. The S-ucOC levels did not increase from baseline. The patient's height growth velocity SDS was +3.99 for 23 months, and no fracture occurred during this observation period. A consistent, predominantly formative state of bone, which maintained higher S-ALP levels and lower S-TRACP-5b levels compared to baseline, could contribute to increased BMD. In addition, no increase in S-ucOC levels from baseline could be associated with no deterioration of bone strength. This case suggests that measurement of BMD and, S-ALP, TRACP-5b and ucOC could be useful for evaluating the trend on bone strength in a paediatric KTR.