Iron indices and survival in maintenance hemodialysis patients with and without polycystic kidney disease

Dialysis and Transplant Considerations in Autosomal Dominant Polycystic Kidney Disease

Autosomal dominant polycystic kidney disease (ADPKD) is the fourth leading cause of kidney replacement therapy. Unfortunately, the need for dialysis or kidney transplantation is a foreseeable outcome for many patients affected by ADPKD. We review some of the unique issues that should be considered in the management of patients with ADPKD who require dialysis or kidney transplantation. The choice of dialysis modality may be influenced by the enlarged kidneys and liver, but peritoneal dialysis should not be excluded as an option, as studies do not consistently show that there is an increased risk for technique failure or peritonitis. The optimal kidney replacement therapy option remains kidney transplantation; however, nephrectomy may be needed if there is insufficient space for the allograft. Living donor candidates from at-risk families need to be excluded from carrying the disease either by diagnostic imaging criteria or genetic testing. Other potential transplant issues, such as malignancy and cardiovascular and metabolic risks, should also be recognized. Despite these issues, patients with ADPKD requiring dialysis or kidney transplantation generally have more favorable outcomes as compared to those with other causes of chronic kidney disease. Further studies are still needed to personalize the therapeutic approach for those receiving kidney replacement therapy and eventually improve clinical outcomes.

Association between Iron Status and Survival in Patients on Chronic Hemodialysis

The aim of this study was to evaluate survival rates according to iron status in patients undergoing maintenance hemodialysis (HD). Thus, the National HD Quality Assessment Program dataset and claims data were used for analysis (n = 42,390). The patients were divided into four groups according to their transferrin saturation rate and serum ferritin levels: Group 1 (n = 34,539, normal iron status); Group 2 (n = 4476, absolute iron deficiency); Group 3 (n = 1719, functional iron deficiency); Group 4 (n = 1656, high iron status). Using univariate and multivariable analyses, Group 1 outperformed the three other groups in terms of patient survival. Using univariate analysis, although Group 2 showed a favorable trend in patient survival rates compared with Groups 3 and 4, the statistical significance was weak. Group 3 exhibited similar patient survival rates to Group 4. Using multivariable Cox regression analysis, Group 2 had similar patient survival rates to Group 3. Subgroup analyses according to sex, diabetic status, hemoglobin level ≥ 10 g/dL, and serum albumin levels ≥ 3.5 g/dL indicated similar trends to those of the total cohort. However, subgroup analysis based on patients with a hemoglobin level < 10 g/dL or serum albumin levels < 3.5 g/dL showed a weak statistical significant difference compared with those with hemoglobin level ≥ 10 g/dL, or serum albumin levels ≥ 3.5 g/dL. In addition, the survival difference between Group 4 and other groups was greater in old patients than in young ones. Patients with a normal iron status had the highest survival rates. Patient survival rates were similar or differed only modestly among the groups with abnormal iron status. In addition, most subgroup analyses revealed similar trends to those according to the total cohort. However, subgroup analyses based on age, hemoglobin, or serum albumin levels showed different trends.

Ciclopirox olamine induces ferritinophagy and reduces cyst burden in polycystic kidney disease

Despite the recent launch of tolvaptan, the search for safer polycystic kidney disease (PKD) drugs continues. Ciclopirox (CPX) or its olamine salt (CPX-O) is contained in a number of commercially available antifungal agents. CPX is also reported to possess anticancer activity. Several mechanisms of action have been proposed, including chelation of iron and inhibition of iron-dependent enzymes. Here, we show that CPX-O inhibited in vitro cystogenesis of primary human PKD cyst-lining epithelial cells cultured in a 3D collagen matrix. To assess the in vivo role of CPX-O, we treated PKD mice with CPX-O. CPX-O reduced the kidney-to-body weight ratios of PKD mice. The CPX-O treatment was also associated with decreased cell proliferation, decreased cystic area, and improved renal function. Ferritin levels were markedly elevated in cystic kidneys of PKD mice, and CPX-O treatment reduced renal ferritin levels. The reduction in ferritin was associated with increased ferritinophagy marker nuclear receptor coactivator 4, which reversed upon CPX-O treatment in PKD mice. Interestingly, these effects on ferritin appeared independent of iron. These data suggest that CPX-O can induce ferritin degradation via ferritinophagy, which is associated with decreased cyst growth progression in PKD mice. Most importantly these data indicate that CPX-O has the potential to treat autosomal dominant PKD.

Different Effects of Iron Indices on Mortality in Patients With Autosomal Dominant Polycystic Kidney Disease After Long-Term Hemodialysis: A Nationwide Population-Based Study

OBJECTIVE

Iron supplementation and erythropoietin stimulating agents (ESAs) are essential for maintaining hemoglobin levels in hemodialysis patients. However, patients with autosomal-dominant polycystic kidney disease (PKD) have higher endogenous erythropoietin levels, so their recommended iron indices for hemodialysis patients may differ. This study evaluated iron profiles, including ferritin levels and transferrin saturation (TSAT) to identify factors affecting mortality in patients on dialysis, and those associated with mortality in patients with and without PKD.

DESIGN

This cohort study from the Taiwan Renal Registry Data System stratified mortality risk by the presence of PKD recorded as the underlying disease.

SUBJECTS

We enrolled 1346 hemodialysis patients with PKD and 82,873 hemodialysis patients without PKD.

MAIN OUTCOME MEASURE

The primary outcome was 3-year all-cause mortality. Predictors included time-averaged and baseline serum ferritin levels and TSAT. Multivariate Cox regression analysis adjusting for age, comorbidities, and relevant laboratory parameters was used to estimate the all-cause hazard ratios (HRs) for mortality.

RESULTS

The mean ages of patients with and without PKD were 56.2±13.2 and 61.7±13.5 years and the median follow-up time was 37 (15-76) months. The adjusted mortality risks for time-averaged ferritin levels >800 ng/mL (HR=1.52; 95% confidence interval: 1.40-1.65) or TSAT levels >50% (HR=1.46; 95% confidence interval: 1.30-1.65) were significantly higher among patients without PKD than those for patients with normal iron indices. However, a U-shaped curve of mortality against ferritin/TSAT levels was not observed in patients with PKD. In the sensitivity test, there was no difference among PKD patients who underwent regular ESA therapy and those who did not.

CONCLUSION

Iron indices have different effects on mortality among patients with and without PKD. Iron supplementation, recommended serum ferritin levels, or TSAT should be monitored in hemodialysis patients, especially those without PKD. Clinicians should consider treating anemia in hemodialysis patients individually, especially in PKD.

Positive Iron Balance in Chronic Kidney Disease: How Much is Too Much and How to Tell?

BACKGROUND

Regulation of body iron occurs at cellular, tissue, and systemic levels. In healthy individuals, iron absorption and losses are minimal, creating a virtually closed system. In the setting of chronic kidney disease and hemodialysis (HD), increased iron losses, reduced iron absorption, and limited iron availability lead to iron deficiency. Intravenous (IV) iron therapy is frequently prescribed to replace lost iron, but determining an individual's iron balance and stores can be challenging and imprecise, contributing to uncertainty about the long-term safety of IV iron therapy.

SUMMARY

Patients on HD receiving judicious doses of IV iron are likely to be in a state of positive iron balance, yet this does not appear to confer an overt risk for clinically relevant iron toxicity. The concomitant use of iron with erythropoiesis-stimulating agents, the use of maintenance iron dosing regimens, and the reticuloendothelial distribution of hepatic iron deposition likely minimize the potential for iron toxicity in patients on HD. Key Messages: Because no single diagnostic test can, at present, accurately assess iron status and risk for toxicity, clinicians need to take an integrative approach to avoid iron doses that impose excessive exposure while ensuring sufficient replenishment of iron stores capable of overcoming hepcidin blockade and allowing for effective erythropoiesis.

Comparison of short-term efficacy of iron sucrose with those of ferric chloride in hemodialysis patients: An open-label study

Background:

It is intriguing and imperative that the comparison of the iron preparations in hemodialysis (HD) patients. This study aimed to observe the short-term efficacy of parenteral iron sucrose and ferric chloride in HD patients.

Materials and Methods:

This was a consecutive 10-week single-blind study in Taiwan. An intravenous iron supplement of 100 mg/week was administered as an infusion in 100 ml of normal saline, until a total dose of 1000 mg was achieved. The primary outcome was evaluated by the changes in serum hematocrit (Hct) levels. The changes in serum Hct and iron indices were evaluated every 2 weeks for 10 weeks. The results were collected from 21 April to 4 July 2013.

Results:

A total of 56 HD patients completed the study. Subjects were randomized into an iron sucrose group (26 patients) and a ferric chloride group (30 patients). Between the two treatment groups, there were no statistically significant differences in the change in serum Hct, ferritin, iron, or total iron binding capacity (P > 0.05). In the iron sucrose group, the increase in Hct levels was statistically significant at weeks 4, 8, and 10. In the ferric chloride group, the increase in Hct levels was statistically significant at week 8. No obvious major side effects were observed in both groups.

Conclusion:

In the study subjects, parenteral iron sucrose was as effective and safe as ferric chloride for treating anemia in HD patients.

Safety concerns about intravenous iron therapy in patients with chronic kidney disease

Anaemia in chronic kidney disease (CKD) is managed primarily with erythropoiesis-stimulating agents (ESAs) and iron therapy. Following concerns around ESA therapy, intravenous (IV) iron is being administered more and more worldwide. However, it is still unclear whether this approach is safe at very high doses or in the presence of very high ferritin levels. Some observational studies have shown a relationship between either high ferritin level or high iron dose and increased risk of death, cardiovascular events, hospitalization or infection. Others have not been able to confirm these findings. However, they suffer from indication biases. On the other hand, the majority of randomized clinical trials have only a very short follow-up (and thus drug exposure) and are inadequate to assess the mortality risk. None of them have tested the role of different iron doses on hard end points. With the lack of clear evidence coming from well-designed and large-scale studies, several data suggest that excessive iron therapy may be toxic in several aspects, ranging from iron overload to tissue damage from labile iron. A number of experimental and clinical data suggest that either excessive iron therapy or iron overload may be a possible culprit of atherogenesis. The process seems to be mediated by oxidative stress. Iron therapy should also be used cautiously in the presence of active infections, since iron is essential for bacterial growth. Recently, the European Medicines Agency officially raised concerns about rare hypersensitivity reactions following IV iron administration. The balance has been in favour of benefits. In several European countries, this has created a lot of confusion and somewhat slowed the run towards excessive use. Altogether, IV iron remains a mainstay of anaemia treatment in CKD patients. However, in our opinion, its excessive use should be avoided, especially in patients with high ferritin levels and when ESA agents are not contraindicated.

Elevated high-density lipoprotein cholesterol and cardiovascular mortality in maintenance hemodialysis patients

BACKGROUND

High-density lipoprotein (HDL) confers protection against atherosclerosis by several different mechanisms. Although in the general population, increasing levels of HDL are associated with reduced cardiovascular (CV) mortality, this association is not well known in patients with chronic disease states such as end-stage renal disease. We hypothesize that the association of serum HDL concentration and its ratio to total cholesterol with all-cause and CV mortality in hemodialysis patients is different from the general population.

METHODS

A 3-year (July 2004 to June 2007) cohort of 33 109 chronic hemodialysis patients was studied in the USA in the dialysis clinics where lipid profile was measured in at least 50% of all outpatients of the clinic during a given calendar quarter. Cox proportional hazard models were adjusted for demographics and case-mix variables and cubic splines were plotted.

RESULTS

Higher HDL concentrations up to 50 mg/dL were associated with better overall survival, while HDL at 60 mg/dL and above was associated with a rise in all-cause and CV mortality. All-cause and CV mortality hazard ratio was 1.28 (1.20-1.38) and 1.08 (1.01-1.16) for HDL <30 mg/dL and 1.05 (1.00-1.10) and 1.08 (1.00-1.16) for HDL ≥ 60 mg/dL, respectively (reference: HDL: 30-<60 mg/dL).

CONCLUSIONS

In contrast to the general population, low total cholesterol to HDL ratio was associated with higher mortality in hemodialysis patients. A U-shaped association between HDL cholesterol level and all-cause and CV mortality exists in hemodialysis patients with HDL between 50 and <60 mg/dL exhibiting the best survival. The underlying mechanisms responsible for these seemingly paradoxical associations await further investigation.