The treatment of hyperphosphatemia is one of the most important therapeutic strategies for chronic kidney disease‒mineral and bone disorder. The oral administration of phosphate binders is essential for achieving both adequate protein intake and efficient improvement of hyperphosphatemia. This study aimed to clarify the phosphate‒lowering effects of lanthanum carbonate and sucroferric oxyhydroxide and how they are influenced by oral antacids, such as proton‒pump inhibitors. We surveyed 163 maintenance hemodialysis patients who were started on either of the abovementioned phosphate binders or had their doses of these drugs increased at one of our facilities between April 2017 and December 2019. The patients’ background characteristics and the changes in their serum phosphate concentrations seen at 4 weeks after drug changes were investigated. Patients who were switched from other phosphate binders or had their dialysis conditions or doses of vitamin D drugs or calcimimetics changed during the observation period were excluded. In the sucroferric oxyhydroxide group, the discontinuation of oral administration due to adverse effects was significantly more common； however, the reduction in the serum phosphate concentration per 250 mg dose was significantly larger than that seen in the lanthanum carbonate group (0.94±0.79 mg/dL vs. 0.51±0.43 mg/dL, p＜0.01). Regarding the effects of antacids, in the lanthanum carbonate group, the reduction in the serum phosphate concentration per 250 mg dose was significantly smaller in the patients taking antacids (0.44±0.45 mg/dL vs. 0.67±0.33 mg/dL, p＜0.01), whereas no such difference was observed in the sucroferric oxyhydroxide group (0.98±0.77 mg/dL vs. 0.86±0.87 mg/dL, p＝0.70). This suggests that the phosphate‒lowering effect of lanthanum carbonate is attenuated by the increase in gastric pH induced by antacids, while the effect of sucroferric oxyhydroxide remains stable under high pH conditions. Great care is required during the selection of phosphate binders and the interpretation of blood test results in patients taking antacids.

We examined the saltiness sensitivity of 128 hemodialysis patients who underwent outpatient maintenance dialysis at our facility and 30 healthy subjects using salt‒impregnated filter paper with various salt concentrations. All of the healthy subjects exhibited normal salt taste recognition, but 42 (32.8％) hemodialysis patients (16 and 26 with moderate and severe salt taste recognition disorder, respectively) were judged to have salt‒related cognitive impairment. Twenty‒one of the patients with salt‒related cognitive impairment were subjected to swallowing exercises and salivary gland massages for 10 minutes before each dialysis session, and 11 (52.4％) demonstrated improved to normal salt taste recognition one month later, and 15 (71.4％) did so 3 months later. However, there were no significant changes in weight gain during dialysis or salt intake in these patients.

［Background］ Continuous hemodiafiltration (CHDF) has the advantage of achieving hemodynamic stability, but 24‒hour dialysis is associated with various problems, such as problems relating to patient restraint, medical staff education, personnel, and high medical costs. We investigated the effects of shortening the duration of dialysis from 24 hours to 8 hours by using CHDF. ［Method］ Twenty‒three patients with preoperative left ventricular ejection fractions of ＜55％ were divided into usual hemodiafiltration (group H) and 8 hours’ hemodiafiltration using CHDF (group L) groups. Using a right ventricular ejection catheter, we studied the changes in right heart parameters, such as right ventricular volume, that occurred during dialysis. ［Results］ Water removal relative to dry weight was larger, the rate of decline in right ventricular end‒diastolic volume was smaller, and the rate of reductions in blood pressure of ≥20％ was lower in group L. Creatinine and potassium levels were slightly higher, but within acceptable limits, in group L. ［Conclusions］ Performing 8 hours of CHDF‒based hemodiafiltration for 3 consecutive days after cardiac surgery enabled safe and sufficient removal of fluids and solution at the expense of dialysis efficiency. This technique may be employed as a simple and useful bridge to routine hemodialysis in medium‒sized hospitals like ours.

The patient was a very‒low‒birth‒weight infant (867 g). Fifty days after birth, he developed necrotizing enterocolitis and underwent surgery. At 5 postoperative days, he developed septic shock. His heart rate exceeded 180 beats/min, his white blood cell count was ＜5,000/μL, and his serum endotoxin concentration exceeded 2,000 pg/mL. These findings met the criteria for polymyxin B immobilized fiber column direct hemoperfusion (PMX‒DHP). We used the ACH‒Σ^Ⓡ system (Asahi Kasei Medical, Japan) to perform PMX‒DHP in this very‒low‒birth‒weight infant (1,275 g) according to the “Guidelines for Acute Blood Purification Therapy for Neonates by Extracorporeal Circulation”. This stabilized the patient’s circulatory dynamics and decreased his serum levels of endotoxins, with no adverse events. Very little data has been reported about PMX‒DHP in very‒low‒birth‒weight infants because the technique requires considerable operator skill, and an appropriate method must be devised at each facility. Here, we report the successful use of PMX‒DHP in a very‒low‒birth‒weight infant along with guidelines for an existing dialysis circuit and a review of the related literature.

An 85‒year‒old male, who had received the optimal dose of apalutamide, an antiandrogen drug, for prostate cancer, was referred to the Department of Dermatology at our hospital with a skin rash on his body and a high fever. He was admitted to our hospital with a diagnosis of toxic epidermal necrolysis (TEN) induced by apalutamide. Although 30 mg prednisolone per day was orally administered as a starting dose, he developed systemic diffuse erythema by about day 27. After a total of 8 sessions of plasma exchange, his skin lesions improved. TEN is a serious adverse drug reaction with a high mortality rate. The efficacy of therapeutic plasma exchange for TEN has been validated in several studies. Since some clinical trials have found that apalutamide‒induced skin rashes occur more frequently in Japanese patients, the incidence of severe cutaneous adverse reactions like that seen in the present case may increase along with the use of apalutamide. Further studies are needed in order to better understand the pathophysiology of such reactions.

COVID‒19 infections can be associated with thrombosis and coagulopathy. A 48‒year‒old male who was undergoing maintenance hemodialysis presented with sudden thrombotic occlusion of his vascular access point； i.e., his arteriovenous fistula (AVF) was filled with a large thrombus. Vascular access interventional therapy (VAIVT) successfully removed all of the thrombus and restored blood flow. Angiography showed no marked stenosis that could be related to the thrombosis. However, the AVF became occluded during the next hemodialysis session, despite the use of sufficient unfractionated heparin. The day after next, VAIVT was performed successfully again, followed by hemodialysis. Although unfractionated heparin was used at a much higher dose than usual, abnormal blood clots were observed in the blood chamber of the dialyzer, which made it impossible to continue. The AVF was completely occluded. A low level of blood oxygen saturation (SpO₂) was recognized during the second round of VAIVT without any marked respiratory symptoms. The patient was diagnosed with a COVID‒19 infection with moderate respiratory failure. This case suggests that a COVID‒19 infection should be considered as a differential diagnosis for thrombotic AVF occlusion without any stenosis, even in the absence of respiratory symptoms.

Thrombotic thrombocytopenic purpura (TTP) is a highly lethal disease requiring urgent intervention. The diagnostic criteria for TTP include a reduction in ADAMTS13 activity to below 10％. However, because it takes time to obtain data regarding ADAMTS13 activity, in some cases treatment should be started before such test results are available. Herein, we report a fulminant case of acquired TTP, which rapidly deteriorated, resulting in death, even though plasma exchange was performed immediately. The patient was a 46‒year‒old male. Approximately one week after the onset of flu‒like symptoms, he showed an acute deterioration of his renal function (a serum creatinine level of 3.37 mg/dL), together with thrombocytopenia and the appearance of schistocytes in his peripheral blood, which made a diagnosis of TTP highly likely. On day 2, plasma exchange therapy was initiated, but the patient responded poorly to this treatment. He then developed a disturbance of consciousness, which required steroid pulse therapy and daily plasma exchange therapy. On day 3, immediately after plasma exchange was started, the patient suddenly exhibited respiratory failure and bradycardia, leading to cardiac arrest, and he died despite cardiopulmonary resuscitation being attempted. On autopsy, multiple petechiae and microthrombi were macroscopically and microscopically observed in small blood vessels in various organs, including the heart and kidneys. Although plasma exchange and steroids are still the most effective therapies for TTP, it is important to be aware that some cases are refractory to these treatments. It is also important to always consider the possibility of TTP in cases of acute kidney injury with thrombocytopenia and to promptly start plasma exchange and steroids, even before confirming the diagnosis, especially for high‒risk patients and those that deteriorate rapidly.

［Objective］ Serum ionized Ca (iCa) level measurements acquired using the ion‒selective electrode method should be obtained within 3 to 4 hours. In whole‒blood gas analysis, the influence of delaying iCa measurements for ＞3 hours was investigated. ［Method］ In 43 hemodialysis patients, 2 mL of whole blood was drawn from an internal shunt before dialysis using a balanced heparin‒coated syringe, and gas analysis was performed promptly. The sample was left for 3.5 hours at room temperature, and then gas analysis was performed again. ［Results］ Comparing the values obtained before and after the sample was left for 3.5 hours revealed the following changes： pH： from 7.375±0.034 to 7.304±0.035, HCO₃： from 20.20±1.85 to 19.91±1.80, base excess： from －4.38±1.85 to －6.10±1.89, pCO₂： from 35.39±3.72 to 40.81±4.12, and lactate from 1.32±0.34 to 3.02±0.44 (all p＜0.001). Despite the presence of acidosis, the subjects’ iCa and pH‒corrected iCa levels decreased from 1.13±0.07 to 1.12±0.08 (p＜0.03) and from 1.12±0.07 to 1.08±0.08 (p＜0.001), respectively. ［Conclusion］ Delaying whole‒blood gas analysis for 3.5 hours resulted in increased lactate, decreased pH, and decreased pH‒corrected iCa levels.

Neutralizing antibody titers were measured in healthy subjects and hemodialysis patients after two doses of a new coronavirus vaccine. The antibody titers of the hemodialysis patients were significantly lower than those of the healthy subjects, and some hemodialysis patients were not antibody‒positive. We consider that dialysis patients produce weaker immune responses and that the vaccine may not be fully effective in some cases. We hope that the measurement of neutralizing antibody titers in dialysis patients after vaccination will lead to evaluations of the risk of infection among these patients.