Chronic kidney disease – mineral bone disorders evaluation in peritoneal dialysis patients: correlation between clinical, biochemical and bone hystology parameters

Abstract

Introduction and Aims. Chronic kidney disease mineral bone disorders (CKD – MDB) is an important complication
in dialysis patients. However studies about this disorder in the peritoneal dialysis (PD) patients are rare and have methodological limitations. The aim of this study is to evaluate the profile of CKD-MBD (clinical, laboratory abnormalities, vascular calcification and renal osteodystrophy) in PD patients. Methodology. 29 PD patients with age ranging from 18 years-old to 65 years-old, in current treatment with PD for at least 6 months, were assessed by laboratory tests, hands and hip radiographs for characterization of vascular calcification and iliac crest biopsy for histomorphometric and immunohistochemistry analysis. Results. The main biochemical characteristics of the studied population were: ionized calcium: 4.84 ± 0.35mg/dl; phosphorus: 4.9 ± 1.74mg/dl; alkaline phosphatase: 108 ± 37.8U / L; iPTH: 355 (75-2435) pg / ml; sclerostin: 1,667.6 1,181.3 ± ng / ml, FGF-23: 494.5 (76-7122) pg / ml, 25 (OH) vitamin D 12.4 ± 7.3ng/ml. Histomorphometric parameters: Turnover: BFR / BS 0.01 (0.001-0.1) μm3/μm2/d; Mineralization: OV / BV 3:32 ± 3.82%; Mlt: 66.8 (83-1098) days Volume: BV / TV: 23.1 ± 8.3% . All patients presented 25(OH) vitamin D deficiency (31%) or insufficiency (69%) and mineralization defects. High and low bone turnover diseases were detected in 48.3% and 51.7% of patients, respectively. There was a predominance of adynamic disease (AD). Vascular calcification was present in 24% of the sample. Low turnover bone disease was associated with vascular calcification. Bone formation rate was negatively correlated to sclerostin levels (r = -0.45 P: 0.01). The trabecular bone volume was preserved in 70% of the patients. Conclusions. The prevalence of low and high turnover bone disease was similar in patients, being the former associated with vascular calcification. The AD was the most common histological type. It is relevant to detect 100% of D hypovitaminosis in the studied patients, so that the replacement of 25 (OH) vitamin D should be considered. Sclerostin, a recently discovered protein produced by osteocytes and which has an inhibitory effect on the bone tissue formation, might play a role in development of low turnover bone disease.