Relationship between blood bone metabolic biomarkers and anemia in CKD patients

Introduction: Blood bone metabolic biomarkers are non-invasive indexes for evaluating renal osteodystrophy (ROD). Here the relationships between blood bone metabolic biomarkers and anemia in chronic kidney disease (CKD) patients are investigated, the effects of parathyroidectomy (PTX) on above indices are analyzed. Methods: In this cross-sectional study, 100 healthy controls and 239 CKD patients, including 46 secondary hyperparathyroidism (SHPT) subgroup with PTX, were enrolled. A prospective study with 28 PTX patients was followed up. The degree of anemia was classified as mild, moderate, and severe based on the tertiles of hemoglobin (Hb) levels of the anemic CKD patients, with cutoff values of 83g/L and 102g/L. Bone metabolic biomarkers, including calcium (Ca), phosphorus (P), intact parathyroid hormone (iPTH), fibroblast growth factor 23 (FGF23) and a-klotho were tested. Results: The mean eGFR in CKD patients was 25.74+-35.99 ml/min/1.73 m2 and 84.10% patients had anemia. The baseline Hb levels in the mild, moderate, and severe anemia subgroups were 110.86+-5.99g/L, 92.71+-5.96g/L and 67.38+-10.56g/L, respectively. CKD patients had higher adjusted Ca, P, ALP, iPTH and FGF23 levels, and lower a-klotho levels than controls. Baseline adjusted Ca, P, iPTH and a-klotho levels were associated with Hb in CKD patients. Blood adjusted Ca, P, iPTH levels were correlated with anemia severity. After PTX (median interval: 6.88 months), anemia and high blood adjusted Ca, P, iPTH and FGF23 levels were ameliorated, while a-klotho levels increased. Conclusions: Blood adjusted Ca, P, iPTH and a-klotho levels were correlated with Hb in CKD patients, correcting ROD is supposed to be therapeutic targets for anemia. Keywords: Anemia; Chronic kidney disease-mineral and bone disorder; Bone metabolic biomarkers; Parathyroidectomy; Secondary hyperparathyroidism