THE ROLE OF PHOSPHORUS, PTH, FGF-23, KLOTHO AND VITAMIN D ON HEMOGLOBIN LEVELS OF PATIENTS WITH CKD

Introduction and Aims: Parathyroid hormone (PTH) is strong predictor of low levels of hemoglobin (Hb) in dialysis patients with severe hyperparathyroidism. Inverse association between PTH and Hb exists in non-dialysis CKD-patients and a doubled risk of Hb <10.0 mg/dL in absence of severely deranged PTH concentration. Higher phosphorus (P) levels associated with a greater likelihood for anemia both in early CKD-stages patients and in subjects with normal kidney function suggesting that P may be a biomarker of anemia. FGF-23 may play a role in the mechanisms leading to anemia through its interplay with serum P, vitamin D and suppression of Klotho. Low Klotho levels associated with senescence, cell toxicity, premature aging, vascular calcifications and deficiency in activated vitamin D. Vitamin D deficiency causes anemia. Aim of the study is to evaluate the role of P, PTH, FGF-23, Klotho and vitamin D on hemoglobin levels of patients with CKD not on dialysis. No previous study has assessed simultaneously these variables in the same study-population. Methods: This is a retrospective observational cohort study in hospitalized patients and outpatients. Exclusion criteria were: stage 5 CKD on dialysis, polycystic kidney disease, past or recent therapy with iron, erythropoietin stimulating agents, or vitamin D sterols, history of bleeding, treatment with warfarin. Presence of anemia was established on levels of Hb ≤11.0 g/dL. This value entered in statistical analysis. Blood samples were collected in the morning in fasting state. Variables were glucose, Hb, iron, ferritin, transferrin saturation (TSAT %), calcium, P, PTH, Vitamin D, FGF-23, Klotho, 24/h proteinuria, 24/h phosphaturia, alkaline phosphatase, uric acid, homocysteine, hs-CRP, triglycerides, total cholesterol, HDL-cholesterol, LDL-cholesterol. Variables significantly associated with Hb at univariate analysis entered into logistic regression analysis to identify predictors of anemia Results: N.170 patients entered the study. Clinical characteristics and biochemistry of patients with and without anemia are in table 1. Results of logistic regression analysis are in table 2. Conclusions: Our study confirms that PTH may be a stronger predictor of anemia in CKD-patients even when its concentration seems not severely deranged. Despite Others have associated P levels with a greater likelihood for anemia in early CKD-stages patients, the predictive role of P seems marginal in respect to PTH in more advanced CKD stages. FGF-23, Klotho and vitamin D levels do not seem to play a role in anemia in this study population. Interestingly, high serum calcium level has a protective action toward anemia.