LABORATORY IMMUNOLOGY AND KIDNEY TRANSPLANTATION

L. Jimeno-garcia¹, M.J. Gonzalez-soriano¹, L. Gil-del castillo², J.A. Noguera-velasco², I. Tovar-zapata², P. Martinez-hernandez^2
1Department Of Nephrology-transplantation, UNIVERSITARY HOSPITAL VIRGEN DE LA ARRIXACA, MURCIA/SPAIN, ²Clinical Laboratory Department, UNIVERSITARY HOSPITAL VIRGEN DE LA ARRIXACA, MURCIA/SPAIN

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Introduction: Renal transplant patients show a rapid loss of bone mass and increased risk of fracture compared with the general population. Osteoporosis is a multifactorial skeletal disease in which the genetic component may influence up to 80%, but few studies explore the influence of genetics in these patients. Objectives: To evaluate the usefulness of biochemical markers of bone turnover (BMBT) versus densitometry (DEXA) as a standard test in the diagnosis of bone disease in renal transplantation. Genotype polymorphism of the type 1 collagen genes (COL1A1-Sp1), calcitonin receptor (CTR-AluI), vitamin D receptor (VDR-FokI, VDR-BsmI) and estrogen receptor (ESRalfa-XbaI, ESRalfa-PvuII) in renal transplant recipient patients, assessing their potential contribution to bone loss and fracture risk and study its correlation with the values of BMBT and DEXA. Material and Methods: We studied 139 kidney transplant patients followed for two years. It determines parathyroid hormone (PTH) by RIA, alkaline phosphatase (ALP), aminoterminal propeptide of procollagen type 1 (P1NP), osteocalcin (OC), beta-crossLaps (BC) and deoxypyridinoline (Dpyr) by electrochimioluminiscence, bone isoenzyme of ALP (ALPo) by ELISA and bone mineral density by dual X-ray absorptiometry (DEXA) in the pretransplant phase, at 6, 12 and 24 meses.We genotyped polymorphisms in 104 patients with low-density microarrays, with the kit Clinical Arrays ® MetaBone, Genomica ®. Statistical analysis: SPSS V15.0. Results: The values of PTH and BMBT decreases at 6 m after transplantation: PTH, ALP, P1NP, OC and BC (p <0.001) and ALPO (p <0.05). Bone density decreases at 6 m from the transplant at lumbar spine and femoral neck (p <0.05). Among the studied MBRO which offers greater diagnostic yield is BC at 6 m. The area under the ROC curve was 0,839 (p = 0.012). The area under the ROC curve of concentrations of PTH, and OC P1NP measured at 6 m for predicting bone loss a year of transplantation contrasted by DXA, gave a great performance diagnosis (PTH = 0.958, p = 0.008; P1NP = 0.896, p = 0.021, OC = 0.854, p = 0.039). VDRB Patients with genotype-BsmI (BB) have lower bone density in pretransplant lumbar spine (p = 0.023). ESR1-XbaI show greater loss of bone mass measured by DEXA at the femoral neck at 6 months (p = 0.009) and posttransplant year (p <0.028). The ESR-PvuII genotype (PP) shows significant differences in baseline training BMBT: lnALP_pre (p = 0.02); lnALPo_pre (p = 0.01); lnOC_pre (p = 0.036)Conclusion: BMBT at 6 m correlate with DEXA a year, suggesting itsusefulness in early diagnosis of bone disease in transplant patients. Polymorphisms of VDRB-BsmI-XbaI and ESR1 genes predispose to greater mass loss bone, suggesting itsutility in the preventive treatment of renal transplant patients susceptible to bone disease.

Disclosure: All authors have declared no conflicts of interest.