Evaulation of relationship between homocysteine, parathyroid hormone, active vitamin D3 and bone mineral density in renal transplant recipients

Introduction and Purpose: Kidney transplantation is the most prominent in terms of morbidity and mortality in chronic renal failure treatment. Due to prolongation of graft survival in patients with chronic kidney transplant complications are encountered more frequently. Osteopenia and osteoporosis, which is characterized by a decrease in bone mineral densitometry, are the most common bone disease after renal transplantation and an important source of morbidity and mortality. After the transplantation, in the first 6 months, significant bone loss is developed. The most important factors that determine the severity of bone disease are, dialysis duration, severity of secondary hyperparathyroidism, the dose and duration of immunosuppressive drugs, kidney functions and the level of Vitamin D3. In this study, a sulfur amino acid, homocysteine is evaulated the relationship between the parameters of parathyroid hormone, active vitamin D3, and bone mineral density which are associated with bone and mineral metabolism in kidney transplant recipients Materials and Methods: In this study, 86 male (%73.5) and 31 woman (%26.5), totally 117 renal transplant patients were included who are followed by Çukurova University Medical Faculty Nephrology department. Informed consent was approved from the patients who agreed to participate in the study. Patients' age, sex, duration of dialysis, transplant duration, types of donors, drugs, the development of post-transplant diabetes were recorded. Also glucose, BUN, creatinine, calcium, phosphorus, sodium, potassium, parathyroid hormone, vitamin D3, albumin, homocysteine, vitamin B12, folate, and 24-hour urine protein were measured. The femoral neck and spine bone mineral density was measured by dual energy X ray absorptiometry method. Results: According to the results of bone mineral density in patients, 14 (12.3%) were normal, 41 (36.2%) were osteoporotic, 58 (51.3%) were osteopenic DEXA measurement. There is a statistically significant relationship between the value of homocysteine and drugs used by patients which are rapamycin (p = 0.05), statins (p = 0.057) and B-blockers (p = 0.01). There is no statistically significance between the drugs and femur and vertebral dexa evaulation. Between the Homocysteine levels and BUN (p = 0.002), creatinine (p = 0.001), vitamin B12 (p <0.001) there is statistically significant negative relationship. Besides, between homocysteine levels and proteinuria (p = 0.031), a weak but statistically positive relationship was showed. Between vitamin D and proteinuria (p=0,0035) there is a negative relationship, between serum albumin(p<0,001) and calcium (p:0,001) there is a positive relationship determined. And It is not found any significant relationship between serum homocysteine levels and bone density of the femur and lumbar vertebrae, Conclusion: Significant association was not found between Homocysteine levels and parathyroid hormone, vitamin D3 and bone mineral density. The bone mineral density was decreased in kidney transplant recipients after transplantation. Vitamin B12 and folate serum homocysteine levels were detected statistically significant relationship and also vitamin B12 and folate supplementation may be one of the treatment options for lowering serum homocysteine levels. Lower serum homocysteine levels are found in Rapamycin users whereas higher levels of homocysteine was found in b blocker and statine users. Should be noted that drugs used to affect the level of serum homocysteine. A positive correlation between urinary protein and serum homocysteine level is not shown in an earlier study so large-scale studies are needed to demonstrate the mechanisms. Key Words: Kidney transplantation, osteoporosis, bone mineral density, homocysteine, vitamin D3, parathyroid hormone.