CLINICAL PROFILE OF MINERAL BONE DISORDERS (RENAL OSTEODYSTROPHY) IN CHRONIC KIDNEY DISEASE PATIENTS

Objective: The objective of the study was to evaluate the clinical profile of mineral bone disorders (renal osteodystrophy) in chronic kidney disease (CKD) patients. Methods: A retrospective study was performed involving 100 patients above 15 years of age with previously diagnosed chronic renal failure. A series of tests such as biochemical, radiological, and arterial calcifications were monitored. The mean age of subjects in our study was 52.54 years. Results: Biochemical tests revealed that hypocalcemia was present in 54% of the patients, and hyperphosphatemia was seen in 84% of the participants, while only 22% of the participants had high alkaline phosphate (ALP) levels. Radiological tests revealed that 39 patients had aortic calcification, 42 patients had radial artery calcification, and 27 patients had both. Subperiosteal resorption was seen on 29 participants. The majority of the vascular calcification and subperiosteal resorption was seen in patients with CKD Stage 5, and both aortic and radial artery calcifications were significantly associated with subperiosteal bone resorption. Conclusion: The results point toward a high prevalence of derangement in the mineral, vascular and valvular calcifications. Serum total ALP can serve as a biochemical marker to identify a pattern of bone turnover where intact parathyroid hormone is not available. The results highlight that serum phosphorus and Ca × P product levels were significantly associated with both aortic and radial artery calcifications. There was no significant association of these calcifications with serum calcium and ALP levels.

FC 124PATTERNS OF RENAL OSTEODYSTROPHY ONE YEAR AFTER KIDNEY TRANSPLANTATION

Background and Aims Bone disease after kidney transplantation is an issue of growing concern, as prolonged graft survival and older age of recipients necessitate focus on long-term health burdens such as osteoporosis and fractures. Pre-existing type of renal osteodystrophy, post-transplant immunosuppressive treatment, and de novo disturbances of mineral metabolism all contribute to bone disease in kidney transplant recipients. The current pattern of renal osteodystrophy after kidney transplantation is not well characterized. This study reports histomorphometric findings of protocolled bone biopsies in a large cohort of kidney transplant recipients 1 year post-transplant. Method Histomorphometric analysis of transiliac bone biopsies with prior tetracycline labelling was performed in 141 kidney transplant recipients. Biochemical measurements included bioactive parathyroid hormone (PTH), total calcium, phosphate, calcidiol, bicarbonate, and sclerostin. Kruskal-Wallis and Wilcoxon signed rank tests were used to evaluate differences across categories and between groups, respectively. Stepwise multivariate linear regression was performed to identify key demographic and biochemical determinants of bone turnover (bone formation rate, BFR), mineralization (mineralization lag time, Mlt), and volume (Bone area, BAr). Results Mean age was 57±11 years, 71% were men, and all were Caucasian. Mean eGFR was 49±16 (range 19 to 106) ml/min/1.73 m². Hyperparathyroidism (PTH > 1.5xUNL) was seen in 48%, hypercalcemia (>10.3 mg/dL) in 18%, hypophosphatemia (<2.3 mg/dl) in 12%, and vitamin D deficiency (<15 ng/mL) in 4% of patients. Categorization of bone turnover, mineralization, and volume is shown in Figure 1. Bone turnover was normal in the vast majority (71%). Patients with low turnover (26%) had received a higher cumulative steroid dose (2.78 vs 2.34g in low vs non-low turnover; p=0.02). Patients with delayed mineralization (16%) were younger (52 vs 58 yrs, p=0.02) and had received a higher cumulative steroid dose (2.85 vs 2.36g, p=0.003). They had higher levels of PTH (124 vs 53 ng/L, p<0.001), and lower levels of phosphate (2.68 vs 3.18 mg/dL, p<0.001), calcidiol (29 vs 37ug/L, p=0.02), bicarbonate (21.3 vs 23.3 mmol/L, p=0.004), and sclerostin (493 vs 594 pg/mL, p=0.03) compared to patients with normal mineralization. Patients with low bone volume tended to be older (61 vs 56 years, p=0.07). Independent determinants of BFR were PTH (β=0.68, p<0.001) and cumulative steroid dose (β = -0.22, p=0.02). Determinants of Mlt were phosphate (β=-0.48, p=0.001) and cumulative steroid dose (β=0.18, p=0.004), and determinants of BAr were age (β=-0.15, p=0.002), and BMI (β=0.33, p=0.002). Conclusion Bone turnover is normal in the majority of kidney transplant recipients at 1 year post-transplant, despite a high prevalence of hyperparathyroidism. Low levels of bicarbonate, phosphate, and calcidiol may contribute to delayed bone mineralization in kidney transplant recipients.

MO799IS COMBINATION OF MAINTENANCE HEMODIALYSIS WITH HEMOPERFUSION AN EFFECTIVE METHOD IN MANAGEMENT OF RENAL OSTEODYSTROPHY AND INFLAMMATION IN HEMODIALYSIS PATIENTS?

Background and Aims Some of the conditions which occur in maintenance hemodialysis (MHD) patients with a high incidence resulting in a decline in their quality of life, include malnutrition, renal osteodystrophy, refractory hypertension and chronic systemic inflammation. In developing countries, due to the low level of economic development, low-flux dialysis is the main means of extracorporeal blood purification therapy. But it can hardly remove the middle and large molecule uremic toxins and protein-bound toxins; as a result, the patients suffer from long-term complications and poor quality of life. In this study, we attempted to investigate whether the combination of maintenance hemodialysis (MHD) with hemoperfusion (HP) could improve the clearance rate of middle and large molecule uremic toxins so as to improve their uremic complications. Method A total of 54 patients, who underwent routine hemodialysis, were assessed in this study. Those patients were randomly divided into two groups: Group 1 (27 patients) received combined treatment of HD with hemoperfusion (HP) in this regimen: HD 2 times a week with HD+HP once a week two times in a row, then after two weeks, and afterwards once a month as a maintenance treatment. Group 2 (27 patients) was only undergoing maintenance HD 3 times a week. The clinical and laboratory properties of both groups were followed up for 18 months, whereas the primary outcomes included normal clinical data, high sensitive C-reactive protein (hsCRP), immunoreactive parathyroid hormone (iPTH), phosphorus (P04), calcium (Ca), albumin, iron (Fe), total iron binding capacity (TIBC), hemoglobin, Epo doses and types of hypertensive drugs. Results At the end of the 18-month observation, the serum concentration of albumin, P04, hsCRP, systolic blood pressure (SBP) and diastolic blood pressure (DBP) were lower with Group 1 than with Group 2 (p<0.05). Whereas, higher levels of iPTH were noticed in group 1, but when the laboratory and clinical data are analysed of the group 1 alone a statistically significant lower values after the observational period are noticed especially in the serum values of iPTH (p<0.05), P04 (p<0.001), CRP (p<0.011), SBP and DBP (p<0.05). Conclusion HD+HP was superior to HD in regularly eliminating middle and large molecule uremic toxins accumulated in the body which is mostly shown through reducing the values of iPTH and hsCRP. These findings suggest a potential role for HD+HP in the treatment of inflammation and renal osteodystrophy as well, because lowering these values of iPTH leads to a normalization of other minerals which is expected and therefore leads to a stabilization of this long-term uremic complications, which can improve the overall general condition of the MHD patient.

FC 076DIAGNOSTIC ACCURACY OF BONE TURNOVER MARKERS IN RENAL OSTEODYSTROPHY

Background and Aims A transiliac bone biopsy is the gold standard for diagnosing renal osteodystrophy, but is not recommended as part of routine clinical workup due to its invasive nature. Suitable non-invasive alternatives have yet to be established. The aim of this study was to investigate the diagnostic accuracy novel biochemical markers of bone remodeling compared to that of biointact parathyroid hormone (PTH) for bone turnover as evaluated by histomorphometry. Method Protocolled bone biopsies were performed in end-stage kidney disease patients (ESKD, n = 80) and kidney transplant recipients (n = 119). Full-length (1-84) PTH, bone-specific alkaline phosphatase (BsAP), intact N-terminal propeptide of type I collagen (P1NP), and tartrate-resistant acid phosphatase isoform 5b (TRAP5b) were measured. Diagnostic performance was evaluated by area under the receiver operator characteristics curve (AUC). Optimal diagnostic cutoffs were established in an exploration cohort (n=100), and subsequently validated in a separate subset of patients (n=99). Results Mean age was 55±13 years, two-thirds were men (67%), and 23% had diabetes mellitus. Post-transplant eGFR was 49 [IQR 39, 59] ml/min/1.73m². Bone turnover was low in 47 (24%), normal in 119 (60%), and high in 33 (17%) patients. All biomarkers differed significantly across categories of bone turnover (p < 0.001). The AUC of biointact PTH for high turnover was 0.82 (0.73, 0.91), which was not significantly different from AUC values for BsAP, Intact P1NP, and TRAP5b (0.87, 0.90, and 0.86, respectively). AUC of biointact PTH for low turnover was 0.71 (0.63, 0.78), which was significantly lower than the values for BsAP, Intact P1NP, and TRAP5b (0.79, 0.83, and 0.79, respectively; p < 0.05, all). Calculated optimal diagnostic cutoffs in the exploration cohort are shown in Table 1. Applying these cutoffs in the validation cohort revealed high negative predictive values for both high (92 - 96%) and low (82 - 90%) bone turnover. Positive predictive values were consistently low. Conclusion The diagnostic accuracies of BsAP, Intact P1NP and TRAP5b are sufficient to rule out both high and low bone turnover in CKD. Biointact PTH shows inferior performance, particularly in kidney transplant recipients.

MO568STATIC PARAMETERS OF HISTOMORPHOMETRY FOR THE EVALUATION OF BONE TURNOVER IN RENAL OSTEODYSTROPHY

Background and Aims A full histomorphometric analysis of a transiliac bone biopsy with prior tetracycline labeling remains the gold standard to diagnose renal osteodystrophy. Bone turnover is primarly evaluated by the dynamic parameter bone formation rate, calculated from the incorporation of tetracycline in bone. In cases of failed tetracycline labels, however, an evaluation of bone turnover based on static parameters is warranted. This study investigates the diagnostic accuracy of static histomorphometric parameters for the diagnosis of high and low bone turnover. Method Bone biopsies with prior tetracycline labeling of sufficient quality for a full histomorpometric analysis were included (n = 205). Mean age of participants was 56±13 years, 67% were men, and 22% had diabetes mellitus. Diagnostic accuracy of static histomorphometric parameters for bone turnover was evaluated by area under the receiver operator characteristics curve (AUC) statistics, against the full set of static and dynamic histomorphometric parameters. The cohort was randomly split to allow calculation of optimal diagnostic cutoffs in an exploration cohort (n=105), with subsequent validation in a separate subset of patients (n=100). Results All histomorphometric parameters were significantly different across categories of low (24%), normal (60%), and high (16%) bone turnover (p < 0.01), and all were significant predictors of both high and low bone turnover (Figure 1). Calculated optimal cutoffs and their sensitivities and specificities in the validation cohort are shown in Table 1. Diagnostic accuracy was very good for high turnover, as the combination of presence of fibrosis with ObPm>5.4%, OcPm>1.5%, and OAr>2.4% provided a correct diagnosis in 94% of patients, with positive (PPV) and negative (NPV) predictive values of 80% and 96%, respectively. Using the same predefined combination, an accuracy of 80% was achieved for low turnover (no fibrosis, ObPm≤1.9% OcPm≤0.9% and OAr≤1.6%), with a PPV of 71% and a NPV of 82%. Conclusion Static histomorphometric parameters provide an acceptable alternative for the diagnosis of high and low bone turnover. In the absence of successful tetracycline labeling, the proposed cutoffs may provide a suitable alternative for the evaluation of bone turnover in renal osteodystrophy.

Uremic Leontiasis Ossea

While renal osteodystrophy is a common complication of chronic renal failure which is caused by secondary hyperparathyroidism, it is rare that the bony changes result in a severe progressive overgrowth of the bones of the face such that the patient is at risk for breathing and feeding difficulties. When this occurs, it is called uremic leontiasis ossea and patients who suffer from this rare, severe complication of renal osteodystrophy may go undiagnosed or be misdiagnosed resulting improper management due to its limited discussion in the literature. We report a case of a 42-year-old man with end-stage renal disease who was unable to receive dialysis consistently for many years who was found to have a large hard mass on the palate and palate ulcers.