Serum Level of Osteopontin in Patients with CKD Stage 5 on Hemodialysis : An Updated Overview

End stage renal disease (ESRD) is the fifth stage of renal failure necessitating dialysis or kidney transplantation. Chronic kidney disease leads to dysregulation of calcium (Ca2+), phosphorus (P), parathyroid hormone (PTH), and vitamin D metabolism, resulting in biochemical laboratory abnormalities, significant bone disease, and/or vascular calcification that define chronic kidney disease–mineral and bone disorder (CKD-MBD). Even with careful monitoring of these markers, patients with ESRD on maintenance hemodialysis have poorer health outcomes related to mineral and bone disorder) MBD, such as increased risk of developing cardiovascular disease and increased fracture risk, )KDIGO, 2017). While obtaining abdominal radiographs, computed tomography–based imaging, or dualenergy X-ray absorptiometry scans or performing a bone biopsy to help evaluate calcification and bone mineral density (BMD) status, the strength of recommendation of these practices are low. Osteopontin (OPN) is a glycol-phosphoprotein found in bone, acute and chronic inflammatory cells, smooth muscle, epithelial, and endothelial cells, neurons and fetal renal tissue and is expressed in the thick ascending limb of the loop of Henle .Some of its functions include increasing macrophage and T-cell counts, perpetuation of inflammation, wound healing, tumor development and progression, roles in diabetes, and possible roles in the regulation of nephrolithiasis and nephrogenesis. OPN was also found to promote angiogenesis, encourage growth and invasion of renal cancer, impact the development of lupus nephritis in patients with systemic lupus erythematosus, and potentially be useful as a marker of acute allograft rejection in kidney transplants. Local increases in OPN in vessel walls have been linked to atherosclerotic plaque formation, inflammation within arteries, and smooth muscle mineralization. The function of OPN in bone is defined by its ability to anchor osteoclasts via the αvβ3 integrin. Chronic Kidney Disease Chronic kidney disease is becoming a major health problem worldwide, associated with significant morbidity and mortality for many patients, defined as abnormalities in the structure or function of the kidney that persist for> 3 months and have an impact on health. CKD can be Turkish Journal of Physiotherapy and Rehabilitation; 32(3) ISSN 2651-4451 | e-ISSN 2651-446X 37750 www.turkjphysiotherrehabil.org asymptomatic and early diagnosis of the disease is difficult (KDIGO, 2012). In undiagnosed and untreated people, CKD can gradually progress to end-stage kidney disease (ESRD), or endstage CKD when expensive renal replacement therapy (RRT) through dialysis or a kidney transplant is necessary to save the patient's life. Can lead to various complications such as anemia and disorders of bone mineral metabolism and poor outcomes, including cardiovascular events, morbidity and mortality (Albalawi et al., 2018). Figure (1): Prognosis of CKD by GFR and albuminuria category. (KDIGO, 2012).