Effect of a Ferric Citrate Formulation, a Phosphate Binder, on Oxidative Stress in Chronic Kidney Diseases-Mineral and Bone Disorder Patients Receiving Hemodialysis: A Pilot Study.

A ferric citrate formulation for treating hyperphosphatemia is a new therapeutic that not only suppresses the accumulation of phosphorus in patients with chronic kidney disease-mineral bone disorders (CKD-MBD), but also ameliorates anemia caused by iron deficiency. In contrast, it has been demonstrated that intravenous iron injection markedly increases oxidative stress. This study was designed to investigate the effect of a ferric citrate formulation on oxidative stress in CKD-MBD patients receiving hemodialysis therapy. Fifteen CKD-MBD patients undergoing dialysis were enrolled in this study. The patients were orally administered a ferric citrate formulation for 6 months. Their plasma phosphorus concentrations remained unchanged with the switch from other phosphorus adsorbents to the ferric citrate formulation. In addition, the ferric citrate formulation generally allowed for dose reduction of an erythropoiesis stimulating agent with an increased hematopoietic effect. The average values of plasma ferritin level increased after the introduction of a ferric citrate formulation, but did not exceed 100 (ng/mL). Interestingly, oxidative stress markers did not increase significantly, and anti-oxidative capacity was not significantly decreased at 6 months after the drug administration. Similarly, no change was observed in any inflammation markers. The ferric citrate formulation induces negligible oxidative stress in CKD-MBD patients receiving dialysis under the present clinical condition.

Effects of raloxifene on bone mineral metabolism in postmenopausal Japanese women on hemodialysis.

In addition to renal osteodystrophy, postmenopausal women on hemodialysis are at high risk for osteoporosis. Recent studies reported the effects of raloxifene, a selective estrogen receptor modulator for osteoporosis, in postmenopausal women. The present study evaluated the efficacy of raloxifene and its effects on bone mineral metabolism in postmenopausal Japanese patients on dialysis. In a prospective, multicentre study, 17 postmenopausal women on chronic hemodialysis with severe osteoporosis (bone mineral density [BMD]≤2 SD by bone densitometry) were treated with 60 mg/day raloxifene hydrochloride for 12 months. The study also included 10 age-matched control women. Vitamin D and calcium salts were not changed during the study. Intact parathyroid hormone (iPTH), serum calcium and phosphorus, and bone resorption marker (NTx) were measured, and BMD were determined by DEXA, at 0, 6, and 12 months after administration of raloxifene. The mean lumbar spine BMD at baseline was similar in the two groups. Raloxifene therapy (for 12 months) improved lumbar spine BMD (by 2.6%) in 53% of the patients, while 70% of the control group showed a reduction in BMD (by 4.0%). Raloxifene significantly decreased serum calcium and increased iPTH. Our results suggested that raloxifene improved trabecular BMD in postmenopausal Japanese women on hemodialysis. The effects of raloxifene on serum calcium and serum iPTH level suggest it improves bone resorption. Vitamin D and/or calcium salts should be added to raloxifene treatment to avoid secondary hyperparathyroidism.

Vitamin D receptor activator reduces oxidative stress in hemodialysis patients with secondary hyperparathyroidism.

Treatment with a vitamin D receptor activator (VDRA) has survival benefits probably related to its effects beyond the traditional role in mineral metabolism. We hypothesized that VDRA reduces oxidative stress in hemodialysis (HD) patients. To test this hypothesis, we investigated the effect of VDRA on the oxidative status of albumin in HD patients with secondary hyperparathyroidism. Eleven HD patients with secondary hyperparathyroidism were treated with calcitriol at an intravenous dose of 1.5 µg/week for four weeks. Serum intact parathyroid hormone, calcium and phosphorus were monitored and we measured the amount of oxidized albumin and albumin hydroperoxides form before and after calcitriol treatment. The ratio of oxidized to un-oxidized albumin was determined as a representative marker of oxidative stress. The radical scavenging activity of albumin was also evaluated. After four weeks of calcitriol therapy, there were no significant changes in serum intact parathyroid hormone, calcium, or phosphorus levels; however, the ratio of oxidized to un-oxidized albumin was markedly decreased and serum thiol content was significantly increased after calcitriol treatment. Furthermore, the radical scavenging activity of albumin was greater after calcitriol treatment compared with that of untreated albumin. Our data suggest that intravenous calcitriol treatment reduces oxidative stress and strengthens antioxidant defenses by inhibiting albumin oxidation in HD patients with secondary hyperparathyroidism.

Comparison of sevelamer hydrochloride with colestimide, administered alone or in combination with calcium carbonate, in patients on hemodialysis.

Since hyperphosphatemia in hemodialysis patients can cause secondary hyperparathyroidism and promotes vascular calcification, serum phosphate (Pi) levels must be controlled by phosphate binders. Although sevelamer and colestimide are known as similar non-calcium, non-aluminum phosphate binders in hemodialysis patients, there are no studies that compare the effects of the two agents as either a monotherapy or in combination with calcium carbonate (CaCO3). We randomly allocated 62 hemodialysis patients with hyperphosphatemia to treatment with sevelamer (3.0 g/day) and colestimide (3.0 g/day). During the study, 35 subjects dropped out, leaving 13 in the sevelamer group and 14 in the colestimide group. After a 2-week CaCO3 washout, all subjects received the monotherapy for 4 weeks and then CaCO3 (3.0 g/day) was added for another 4 weeks. Serum corrected calcium levels tended to decrease in both groups during the washout period and monotherapy, but there was no significant difference between the two groups after the addition of CaCO3. Although the calcium x phosphorus product (Ca x P) in the two groups increased during the washout period, there was no significant change or difference between the two groups during monotherapy. However, the addition of CaCO3 significantly reduced serum Pi at Week 8 compared to that at Week 0 in both groups, and significantly lowered Ca x P only in the sevelamer group, but not in the colestimide group(.) In this short-term study, sevelamer and colestimide similarly ameliorated hyperphosphatemia, but the combination of sevelamer and CaCO3 was more effective than colestimide with CaCO3 in controlling the Ca x P product, and it may improve cardiovascular mortality in hemodialysis patients.

Combination therapy of intravenous maxacalcitol and percutaneous ethanol injection therapy lowers serum parathyroid hormone level and calcium x phosphorus product in secondary hyperparathyroidism.

BACKGROUND: Percutaneous ethanol injection therapy (PEIT) is an alternative treatment for secondary hyperparathyroidism (SHPT). Although maxacalcitol has been recently developed as a new vitamin D3 and its efficacy is anticipated in SHPT, there are only few reports on the usefulness of combination therapy of intravenous maxacalcitol and selective PEIT. METHODS: The study population comprised 10 hemodialysis patients (6 males and 4 females, mean age; 51.5 +/- 13.5 years, mean HD period 13.7 +/- 3.5 years), with high intact-PTH level (>400 pg/ml) and 1 or 2 enlarged parathyroid glands detected by power Doppler ultrasonography. Intravenous maxacalcitol therapy commenced one week after PEIT at 15 microg/week. The effect of combination therapy was monitored by measuring intact-PTH, serum Ca and P, bone metabolic markers, parathyroid gland volume and bone mineral density, prior to and at 6 and 12 months after PEIT. RESULTS: Successful control of intact-PTH, bone metabolic markers and parathyroid gland volume was achieved using the combination therapy. Serum P and CaxP product were significantly decreased 12 months after PEIT. The mean values of serum intact-PTH, P and CaxP product fulfilled all of the K/DOQI guidelines at 12 months after PEIT. None of the patients developed complications related to PEIT-maxacalcitol therapy during 12 months following PEIT. CONCLUSION: Combination therapy of intravenous maxacalcitol therapy and selective PEIT is safe and effective for the treatment of refractory SHPT. This combination therapy results in suppression of PTH secretion, regression of parathyroid hyperplasia and the control of CaxP product, which may prevent calcific uremic arteriolopathy in dialysis patients.

Efficacy of percutaneous ethanol injection therapy for secondary hyperparathyroidism in patients on hemodialysis as evaluated by parathyroid hormone levels according to K/DOQI guidelines.

Secondary hyperparathyroidism (SHPT) is a major complication of hemodialysis patients. Recently, percutaneous ethanol injection therapy (PEIT) has become a useful alternative treatment to parathyroidectomy (PTx). In this study, we evaluate the usefulness of PEIT for SHPT according to Kidney Disease Outcomes Quality Initiative (K/DOQI) guidelines. We studied 28 patients on hemodialysis with high intact-PTH (>400 pg/mL) and one to four swollen parathyroid glands detected by power Doppler ultrasonography. They were classified into Group 1 (N = 16), with 1 or 2 swollen glands, Group 2 (N = 5), with 3 or 4 swollen glands, and Group 3 (N = 7), high-risk patients for PTx. We compared serum intact-PTH levels 1 year after PEIT according to K/DOQI guidelines among these groups. We also evaluated the effectiveness of PEIT and PTx by comparing intact-PTH levels in 21 patients 1 year after PEIT (groups 1 and 2) with 11 patients after PTx. In Group 1, adequate intact-PTH levels were noted in 13 of 16 (81.2%) patients after PEIT, while 1 patient of 5 (20%) was achieved in Group 2, and 2 of 7 (28.6%) patients of Group 3. Adequate intact-PTH levels were attained in 14 of 21 (66.7%) patients of the PEIT group but only in 2 of 11 (18.2%) patients of the PTx group. Our results suggest that PEIT is a useful treatment for SHPT, especially in patients with one or two swollen glands. Through appropriate selection of patients for PEIT and correct injection of ethanol into the enlarged parathyroid gland, PEIT could accomplish better outcomes based on K/DOQI guidelines.