Compared effects of calcium and sodium polystyrene sulfonate on mineral and bone metabolism and volume overload in pre-dialysis patients with hyperkalemia

Background

Hyperkalemia is prevalent in end-stage renal disease patients, being involved in life-threatening arrhythmias. Although polystyrene sulfonate (PS) is commonly used for the treatment of hyperkalemia, direct comparison of effects between calcium and sodium PS (CPS and SPS) on mineral and bone metabolism has not yet been studied.

Methods

In a randomized and crossover design, 20 pre-dialysis patients with hyperkalemia (>5 mmol/l) received either oral CPS or SPS therapy for 4 weeks.

Results

After 4-week treatments, there was no significant difference of changes in serum potassium (K) from the baseline (ΔK) between the two groups. However, SPS significantly decreased serum calcium (Ca) and magnesium (Mg) and increased intact parathyroid hormone (iPTH) values, whereas CPS reduced iPTH. ΔiPTH was inversely correlated with ΔCa and ΔMg (r = ?0.53 and r = ?0.50, respectively). Furthermore, sodium (Na) and atrial natriuretic peptide (ANP) levels were significantly elevated in patients with SPS, but not with CPS, whereas ΔNa and ΔANP were significantly correlated with each other in all the patients. We also found that ΔNa and Δ(Na to chloride ratio) were positively correlated with ΔHCO₃ ^?. In artificial colon fluid, CPS increased Ca and decreased Na. Furthermore, SPS greatly reduced K, Mg, and NH₃.

Conclusion

Compared with SPS, CPS may be safer for the treatment of hyperkalemia in pre-dialysis patients, because it did not induce hyperparathyroidism or volume overload.

     

Relapse of nephrotic syndrome during post-rituximab peripheral blood B-lymphocyte depletion

Background

Rituximab is effective against complicated childhood steroid-dependent nephrotic syndrome (SDNS). Peripheral blood B-lymphocyte (B-cell) depletion is strongly correlated with persistent remission, relapse rarely occurring during B-cell depletion; however, we have encountered several such patients.

Methods

We retrospectively analyzed the characteristics and clinical course of 82 patients with SDNS treated with rituximab from January 2007 to December 2012 in our institution.

Results

Six of 82 patients (7.3%) had relapses during B-cell depletion after receiving rituximab (relapsed group). The remaining 76 patients did not have relapses during B-cell depletion (non-relapsed group). The median time to initial relapse during B-cell depletion was 85 days after receiving rituximab, which is significantly shorter than in the non-relapsed group (410 days, p = 0.0003). The median annual numbers of relapses after receiving rituximab were 2.5 and 0.9 in the relapsed and non-relapsed groups, respectively (p < 0.0001). Five patients in the relapsed group also had a total of 10 relapses after B-cell recovery; their median time from B-cell recovery to initial relapse was significantly shorter than in the non-relapsed group (31 vs. 161 days, p = 0.014). Number of relapses before rituximab, history of steroid resistance, onset age, previous treatment, time to ceasing steroids after rituximab, and duration of B-cell depletion did not differ between the two groups.

Conclusion

Relapse during B-cell depletion after receiving rituximab suggests that various pathophysiological mechanisms play a part in childhood nephrotic syndrome.

     

Low frequency of cervicocranial artery involvement in Japanese with renal artery fibromuscular dysplasia compared with that of Caucasians

Background

Fibromuscular dysplasia (FMD), which usually affects the renal artery, also affects the carotid, vertebral, and intracranial arteries. Previous studies have shown a high prevalence of concomitant renal artery and cervicocranial lesions in FMD patients. However, the analyzed subjects were mostly Caucasians in Western countries.

Method

We performed a retrospective analysis to examine the prevalence of cervicocranial vascular lesions in Japanese FMD patients with renal artery involvement at a single institution. The presence of cervicocranial lesions was evaluated by Doppler echography and magnetic resonance angiography. We compared this prevalence with that reported in the literature.

Result

Thirty-one Japanese FMD patients with renal artery lesions were studied. The mean age was 30?±?12 years, 71% were women, and 16% were smokers; all patients were Asians and had hypertension. Multifocal, tubular, and unifocal types of renal lesions were found in 52, 35, and 13% of patients, respectively. Bilateral renal lesions were found in 13% of patients. None of the patients had a cervical vascular lesion associated with FMD. Only two patients (8%) had a lesion in the intracranial artery, of which one was a known case of moyamoya disease.

Conclusion

These findings suggest that cervical artery involvement and intracranial artery involvement are not common in renal FMD patients in Japan, which is in contrast to the data reported for Caucasian patients in Western countries. Ethnic differences could influence the occurrence of cervicocranial lesions. A study with a larger sample size should be performed to validate these findings.

     

Serum phosphate level at initiation of dialysis is associated with all-cause mortality: a multicenter prospective cohort study

Introduction: As glomerular filtration rate (GFR) decreases, serum phosphate level increases. Previous reports indicated that serum phosphate level was associated with mortality in patients on dialysis. However, few reports have examined the association using dialysis initiation as the baseline period.

Methods: This was a multicenter prospective cohort analysis including 1492 patients. Patients were classified into four quartiles based on the serum phosphate level at dialysis initiation, with Q1 being the lowest and Q4 the highest. All-cause mortality after dialysis initiation was compared using the log-rank test. The propensity score represented the probability of being assigned to group Q1 or Q2–4. All-cause mortality was compared in propensity score-matched patients by using the log-rank test for Kaplan–Meier curves. All-cause mortality of Q1 was compared with that for Q2–4 using multivariate Cox proportional hazard regression analysis. All-cause mortality was also determined among stratified groups with or without use of phosphate binders.

Results: Significant differences in cumulative survival rates were observed between the four groups (p?p?=?.046). All-cause mortality was significantly higher in the Q1 group after adjustment for history of CAD (hazard ratio [HR]?=?0.76, 95% confidence interval [CI]: 0.58???1.00, p?=?.048). However, there was no significant difference between the two groups after adjustment for estimated GFR.

Conclusion: The serum phosphate level at the time of dialysis initiation was associated with all-cause mortality. However, the serum phosphate level was dependent on the renal function.     

Alteration of the Intestinal Environment by Lubiprostone Is Associated with Amelioration of Adenine-Induced CKD

The accumulation of uremic toxins is involved in the progression of CKD. Various uremic toxins are derived from gut microbiota, and an imbalance of gut microbiota or dysbiosis is related to renal failure. However, the pathophysiologic mechanisms underlying the relationship between the gut microbiota and renal failure are still obscure. Using an adenine-induced renal failure mouse model, we evaluated the effects of the ClC-2 chloride channel activator lubiprostone (commonly used for the treatment of constipation) on CKD. Oral administration of lubiprostone (500 µg/kg per day) changed the fecal and intestinal properties in mice with renal failure. Additionally, lubiprostone treatment reduced the elevated BUN and protected against tubulointerstitial damage, renal fibrosis, and inflammation. Gut microbiome analysis of 16S rRNA genes in the renal failure mice showed that lubiprostone treatment altered their microbial composition, especially the recovery of the levels of the Lactobacillaceae family and Prevotella genus, which were significantly reduced in the renal failure mice. Furthermore, capillary electrophoresis–mass spectrometry-based metabolome analysis showed that lubiprostone treatment decreased the plasma level of uremic toxins, such as indoxyl sulfate and hippurate, which are derived from gut microbiota, and a more recently discovered uremic toxin, trans-aconitate. These results suggest that lubiprostone ameliorates the progression of CKD and the accumulation of uremic toxins by improving the gut microbiota and intestinal environment.