Low 1,25-dihydroxyvitamin D level is associated with erythropoietin deficiency and endogenous erythropoietin resistance in patients with chronic kidney disease

Resistance to Epoetin-Stimulating Agents in Children Receiving Renal Replacement Therapy

The incidence of anemia increases with the stage of chronic kidney disease (CKD). Erythropoietin (EPO) deficiency is a common cause of anemia in CKD. Erythropoietin-stimulating agents (ESAs) are the mainstay of the treatment. Treatment can be challenging due to erythropoietin resistance (ER), which can be assessed using the erythropoietin resistance index (ERI). Our aim was to investigate the factors contributing to high ERI levels in children receiving renal replacement therapy (RRT). Thirty-three children receiving RRT for at least 3 months were included. The mean ERI value was 15.7 IU/kg/w/g/dL. A significant association was observed between serum phosphorus levels and ERI (P = .016, r = 0.41). The mean parathormone (PTH) level was also higher in the high ERI group (599 ± 351 vs 392 ± 320 pg/mL, P = .088). An association, approaching statistical significance, was found between ERI and hypertension (P = .06, r = 0.32). Our study indicated a potential relationship between hyperphosphatemia, possibly secondary hyperparathyroidism, and ERI in children undergoing RRT.

A retrospective view of the relationship of soluble Fas with anemia and outcomes in chronic kidney disease

BACKGROUND

Anemia is common in chronic kidney disease (CKD) and is associated with outcomes. In addition, serum soluble Fas (sFas) levels are related to anemia and erythropoietin (EPO) resistance.

OBJECTIVES

Firstly, to compare clinical data and serum levels of sFas, EPO, and pro-inflammatory markers between patients with non-dialytic CKD (NDD-CKD) and healthy subjects. Subsequently, to compare and evaluate the relationship of serum EPO, sFas levels with anemia, and outcomes in patients with NDD-CKD over a long follow-up period.

METHODS

We performed a retrospective study in 58 NDD-CKD patients compared with 20 healthy subjects on complete blood count, kidney function, serum EPO, sFas, and inflammatory markers (CRP, IL- 6, and IFN-γ) at baseline. We then compared the same baseline data between patients with NDD-CKD who evolved to anemia and those who did not have anemia over the follow-up. We also evaluated the frequency of outcomes in patients with CKD with higher sFas levels. Finally, we performed a multivariate analysis of factors associated with CKD anemia.

RESULTS

There were lower eGFR and Hb but higher serum inflammatory markers, sFas levels, sFas/eGFR, and EPO/Hb ratios in patients with NDD-CKD. Comparatively, on the other hand, NDD-CKD patients with anemia had lower eGFR but were older, had more diabetes, and had higher sFas/ eGFR, EPO/Hb ratios, and serum levels of IL-6 and sFas than NDD-CKD without anemia for an extended period. In addition, there was an association in a multivariate analysis of diabetes, age, and sFas levels with kidney anemia. Furthermore, there were higher frequencies of outcomes in increased serum sFas levels.

CONCLUSION

As an elective risk factor, serum sFas levels, in addition to age and diabetes, were independently associated with kidney anemia for an extended period. Thus, more studies are necessary to analyze the proper relationship of sFas with kidney anemia and its outcomes and therapy in CKD.

1,25-dihydroxyvitamin D deficiency is independently associated with cardiac valve calcification in patients with chronic kidney disease

Cardiac valve calcification is highly prevalent in patients with chronic kidney disease (CKD). Low vitamin D levels are associated with vascular calcification in CKD. However, the association between vitamin D levels and cardiac valve calcification is unknown. A total of 513 patients with pre-dialysis CKD were included in this cross-sectional study. Aortic valve calcification (AVC) and mitral valve calcification (MVC) were assessed using two-dimensional echocardiography. The associations between AVC and MVC and baseline variables were investigated using logistic regression analyses. In multivariable analysis, serum 1,25(OH)2D level was independently associated with AVC (odds ratio [OR], 0.87; P < 0.001) and MVC (OR, 0.92; P < 0.001). Additionally, age, diabetes, coronary heart disease, calcium × phosphate product, and intact parathyroid hormone levels were independently associated with AVC and MVC. Systolic blood pressure was independently associated with AVC. A receiver-operating characteristic (ROC) curve analysis showed that the best cutoff values of serum 1,25(OH)2D levels for predicting AVC and MVC were ≤ 12.5 and ≤ 11.9 pg/dl, respectively. Serum 1,25(OH)2D deficiency is independently associated with AVC and MVC in patients with CKD, suggesting that serum 1,25(OH)2D level may be a potential biomarker of AVC and MVC in these patients.

Crosstalk of fibroblast growth factor 23 and anemia-related factors during the development and progression of CKD (Review)

Fibroblast growth factor 23 (FGF23) plays an important role in the development of chronic kidney disease-mineral bone disorder (CKD-MBD). Abnormally elevated levels of 1,25-dihydroxyvitamin D cause osteocytes to secrete FGF23, which subsequently induces phosphaturia. Recent studies have reported that iron deficiency, erythropoietin (EPO) and hypoxia regulate the pathways responsible for FGF23 production. However, the molecular mechanisms underlying the interactions between FGF23 and anemia-related factors are not yet fully understood. The present review discusses the associations between FGF23, iron, EPO and hypoxia-inducible factors (HIFs), and their impact on FGF23 bioactivity, focusing on recent studies. Collectively, these findings propose interactions between FGF23 gene expression and anemia-related factors, including iron deficiency, EPO and HIFs. Taken together, these results suggest that FGF23 bioactivity is closely associated with the occurrence of CKD-related anemia and CKD-MBD.

High Erythropoiesis Resistance Index Is a Significant Predictor of Cardiovascular and All-Cause Mortality in Chinese Maintenance Hemodialysis Patients

Background

Renal anemia is a common complication of hemodialysis patients. Erythropoietin (EPO) hyporesponsiveness has been recognized as an important factor to poor efficacy of recombinant human erythropoietin in the treatment of renal anemia. More importantly, increased erythropoiesis resistance index (ERI) may be associated with inflammation and increased mortality.

Objective

The objective of this research was to investigate correlated factors of EPO responsiveness and to clarify the relationships between EPO hyporesponsiveness and cardiovascular mortality and all-cause mortality among maintenance hemodialysis patients.

Methods

This prospective cohort study enrolled 276 maintenance hemodialysis patients for a 55-month follow-up to investigate the factors related to ERI and its relationship to all-cause mortality and cardiovascular mortality.

Results

ERI was positively correlated with predialysis serum high-sensitivity C-reactive protein (r = 0.234, p < 0.001), alkaline phosphatase (r = 0.134, p = 0.028), and ferritin (r = 0.155, p = 0.010) and negatively correlated with albumin (r = −0.206, p < 0.001) and creatinine (r = −0.232, p < 0.001). As multiple linear regression showed, predialysis serum albumin, high-sensitivity C-reactive protein, ferritin, and creatinine were independent correlated factors of ERI (p < 0.05). Kaplan–Meier curves showed that the cumulative incidences of both cardiovascular mortality and all-cause mortality were significantly higher in patients with ERI > 11.04 IU/kg/w/g/dL (both p < 0.01). The high ERI group was significantly associated with higher risk for all-cause mortality (OR 1.781, 95% CI 1.091 to 2.910, p = 0.021) and cardiovascular mortality (OR 1.972, 95% CI 1.139 to 3.417, p = 0.015) after adjusting for confounders.

Conclusions

Predialysis serum albumin, high-sensitivity C-reactive protein, ferritin, and creatinine were independent correlated factors of EPO responsiveness among maintenance hemodialysis patients. Patients with higher ERI values had a higher all-cause mortality rate and cardiovascular mortality rate.

Association between serum magnesium and anemia in patients with chronic kidney disease

PURPOSE

An inverse association was shown between serum magnesium levels and anemia in the general population. However, limited information is available about the association between serum magnesium level and anemia in the patient population with chronic kidney disease. We aimed to investigate the relationship between hypomagnesemia and anemia in pre-dialysis patients with chronic kidney disease stage 3-5.

METHODS

This cross-sectional retrospective study included 213 chronic kidney disease patients with an estimated glomerular filtration rate of 60 mL/min and below. Laboratory and demographic data of outpatients were collected in January 2018-January 2019. Patients with a magnesium level below 1.9 mg/dL were accepted as the hypomagnesemia group.

RESULTS

Serum magnesium level of 62 (29.1%) of these patients were below 1.9 mg/dL. Compared with normomagnesemic patients, hypomagnesemic patients had lower mean hemoglobin values (11.3 g/dL vs. 12.7 g/dL, P < 0.001), proton-pump inhibitor usage rates were significantly higher (33.9% vs. 17.2%, P = 0.008) and the median urine protein/creatinine ratio was found to be significantly higher (1017.5 mg/gCr vs. 536 mg/gCr, P = 0.045). In the multivariate analysis, the use of hemoglobin (OR 0.634; 95% CI 0.505-0.795; P < 0.001) and proton-pump inhibitor (OR 2.670; 95% CI 1.113-6.318; P = 0.025) were independent predictors of hypomagnesemia.

CONCLUSIONS

Hypomagnesemia is a common electrolyte disorder in pre-dialysis CKD patients. In this patient group, anemia is independently associated with hypomagnesemia.