[Chronic kidney disease - Mineral bone disorders: Physiopathology and guidelines]. / Troubles minéraux et osseux dans la maladie rénale chronique : physiopathologie, conséquences et prise en charge.

Chronic Kidney Disease (CKD) is associated with a strong impact on phosphocalcic homeostasis, due to the chronic reduction in glomerular filtration rate (GFR) (phosphate excretion decrease), the inhibition of calcitriol synthesis and dietary restrictions. CKD-Mineral and Bone Disorders (CKD-MBD) must be monitored in CKD patients with biological work-up associated with bone markers and bone density dual X-ray absorptiometry. Adapted diet (phosphate restriction, normalization of calcium intake) and medications (vitamin D, phosphate binders, calcimimetics) help to correct CKD-MBD. Serum parathormone must be kept between 2 to 9 times the usual values, to limit renal osteodystrophy and avoid tertiary hyperparathyroidism. CKD patients are also at risk of artery calcifications, which can significantly increase the morbidity and mortality of the affection. Bisphosphonates may be used after correction of biological abnormalities, in patients with estimated GFR above 30ml/min/1,73m2. Even if transplantation aims to normalize kidney function, kidney transplant recipients remain at risk of CKD-MBD. Biology and bone density dual X-ray absorptiometry must be regularly assessed, especially in the few months following the transplantation. More studies are needed to know if treatments of CKD-MBD are well tolerated in severe CKD and if they are associated with a decrease of bone fracture and vascular calcifications.

New rules of ABO-compatibility in kidney transplantation.

ABO compatibility rules in kidney transplantation have been deeply modified with the possibility of ABO-incompatible transplantation. The recipient has to be prepared in the days preceding surgery with an objective of ABO antibody titers of 1/8 or less. This is obtained through a procedure including antibody removal, rituximab and IV immunoglobulins alone or in association according to the initial titer. All ABO combinations are possible. Due to the preparation of the recipient, living related transplantation has been first carried out but ABO-incompatible transplantation from a deceased donor is becoming common practice in some countries (A2 or A2B donor to a B recipient). Lower uncensored graft survival has been reported by some studies but not when ABO-incompatible kidney transplantations were compared with matched ABO-compatible ones. The infectious risk in the perioperative period, consequence of higher immunosuppression, raises concern. The interlaboratory variability in hemagglutination anti-A/B assays remains an important question among cohort studies which leads to development of new tests. ABO-incompatible transplantation is associated with a rare process, accommodation, that is well known in xenotransplantation and according to which, the transplant is protected against the consequences of ABO antibody binding. In human kidney ABO-incompatible transplantation, few studies are available but suggest that this protection against the post-transplant antibody rebound might be mediated by the expression of anti-complement molecules by endothelial cells.