Bone Microarchitecture in the Transplant Patient

The optimal management of calcium and phosphate metabolism regulation in chronic kidney disease (CKD) is important in preventing fracture risk and vascular calcification and thus morbidity and mortality, global and vascular.

Kidney transplant in a CKD context, usually with a pre-existing underlying renal osteodystrophy, malnutrition, chronic inflammation, hypogonadism and immunosuppression protocols still often made up of high-dose corticosteroid therapy, are all theoretical factors of post-transplantation bone disease. For other solid organ transplants, even though there is generally no underlying renal osteodystrophy before the transplant, the proportion of osteoporotic patients at the time of transplant is substantial. The bone risk in the immediate post-transplant period is notable.

Patients' follow-up is based on biological, radiological and histological tools. Bone densitometry (DXA) is used to measure bone mass. However, recent international recommendations do not consider DXA as a valid tool to assess bone health in CKD patients. Moreover, it is less informative than peripheral quantitative tomography resolution (HR-pQCT). This latest technique, available in Lyon and Saint-Etienne, is more precise, allowing a three-dimensional study of the trabecular microarchitecture and compartmental volumetric bone density (total, cortical, trabecular), while similar to DXA in terms of radiation (less than 5 μSv). The prevention of cardiovascular risk factors is also part of the daily care of patients with a regular cardiac monitoring (heart ultrasound) and vascular (blood pressure, Doppler of the supra-aortic trunks).

TRANSOS study aims to evaluate in a prospective cohort (longitudinal follow-up of 6 months), the bone status in patients receiving solid organ transplantation in the University Hospitals of Lyon and Saint-Etienne, using DXA and HR-pQCT (at baseline and month 6), in combination with classical biological and cardiovascular monitoring. Transplantation is an important activity in these two hospitals and this protocol provides the same bone follow-up for all solid organ transplants, with a reliable, efficient, non-invasive and low-dose radiation tool.

The primary objective of TRANSOS study is to evaluate changes in tibial cortical density between the baseline and the 6th month post-transplant measured by HR-pQCT.