Intravenous (IV) iron can modulate fibroblast growth factor 23 (FGF23) concentrations and cause transient but significant hypophosphataemia. However, it is unknown what other markers might be involved, especially in different patient groups. This study aimed to determine changes in bone and haematinic biomarkers following IV ferric carboxymaltose (FCM) and to identify risk factors for hypophosphataemia in pregnant subjects and those with chronic kidney disease (CKD). Changes in bone [serum FGF23, fractional excretion of phosphate urinary fractional excretion of phosphate (FE_Pi), serum phosphate and serum vitamin D derivatives] and haematinic [plasma hepcidin, serum ferritin and transferrin saturation (TSAT)] biomarkers after 1 g of IV FCM were followed in iron-deficient pregnant and CKD patients and compared with controls (estimated glomerular filtration rate > 60 mL/min/1.73 m²). Data were collected at baseline and up to 42 days after infusion. Risk factors for post-FCM hypophosphataemia were also assessed. Sixty-five subjects completed the study (control, n = 20; pregnant, n = 20; CKD, n = 25). A uniform but variable increase across groups was seen in intact FGF23 (peak Day 2), whereas c-terminal FGF23 varied markedly. Trough serum phosphate timed with the peak FE_Pi at Day 7, recovering by Day 21 in the pregnant group and Day 42 in other groups. Independent predictors of a low phosphate nadir included baseline phosphate, FE_Pi and weight-adjusted FCM dose. All groups showed an early and marked increase in plasma hepcidin (peak Day 2), serum ferritin and TSAT (peak Day 7 for both). Changes in bone and haematinic biomarkers differ between patient groups following IV FCM. For patients with lower serum phosphate concentrations, limiting the dose and measuring levels 7 days after administration may mitigate clinically significant hypophosphataemia.

Nephrotoxin-mediated kidney injury is an important clinical problem, as it can lead to acute kidney injury and chronic kidney disease. Both entities are associated with significant morbidity, increased hospitalisation, healthcare utilisation, and cardiovascular mortality. With the loss of kidney function, there is an accumulation of uraemic toxins, of which the protein-bound toxins—indoxyl sulphate and p-cresyl sulphate—can further inflict damage to the kidneys and the cardiovascular system, culminating in a vicious cycle. Therefore, it is imperative that clinicians have a firm understanding of the common causes and mechanisms of toxin-mediated kidney injury, as well as their clinical presentations and histopathologic features, in order to reduce the prevalence of this pernicious condition.

Chronic kidney disease is a global health burden with a rising incidence and prevalence in developed and developing nations. Once established, it results in a progressive accumulation of a myriad of uraemic toxins. Peritoneal dialysis (PD) uses the body’s peritoneal membrane to remove these toxins across a semipermeable membrane to restore and maintain homeostasis. Traditionally, dialysis adequacy has been measured through clearance of urea and creatinine. However, numerous studies have shown marginal links comparing the clearance of urea and creatinine with clinical outcomes reflected in the recent changes to the ISPD guidelines on dialysis adequacy. Instead, attention has focused on protein-bound uraemic toxins (PBTs). Produced by gut bacteria, these molecules are highly protein-bound and poorly removed by either dialysis or absorptive agents. Elevated concentrations of molecules such as p-cresyl sulfate and indoxyl sulfate have been associated with abnormal cellular function and poor patient outcomes. However, widespread use of these measures to determine dialysis adequacy has been limited by the need for specialized techniques required for measurement. Altering the gut microbiome to reduce generation of PBTs through increased dietary fiber might be an alternate approach to better patient outcomes, with some initial positive reports. This report explores advantages and limitations of measuring uraemic toxins in PD, now and in the foreseeable future.

There is a paucity of data on the sterility of peritoneal dialysis fluid (PDF) after drug admixture. International Society for Peritoneal Dialysis (ISPD) guidelines suggest using sterile technique when admixing antibiotics; however, the degree of sterility remains unclear. This issue is most pertinent when preparing take-home PDF for outpatient treatment of peritonitis. This study compares the sterility of PDF admixed with antibiotics using a non-touch aseptic technique (NTAT) versus sterile technique. Groups of 8 PDF mixtures (1.5% Dianeal or Icodextrin [Baxter International Inc., Spring Grove, IL, USA]) were admixed with 1 g/L ceftazidime and vancomycin, or 20 mL saline, either by a pharmacist using sterile technique in a sterile suite, or a nurse in a clinical room using NTAT. Dianeal inoculated with 1 x 10⁶ colony-forming units (CFU)/L of coagulase-negative Staphylococcus (CNS), with and without antibiotics, served as positive controls. Admixed PDFs were left at room temperature for 72 hours, then cultured using the BacT/ALERT system. A positive culture by day 5 constituted a contamination. Differences in proportion of contamination between groups were assessed using the Chi-squared test. Eighty PDF bags underwent microbiological testing. Sterility was maintained in all bags, independent of technique (NTAT versus sterile technique), type of PDF (Dianeal versus Icodextrin), or whether antibiotics were admixed. Of the positive controls, CNS-inoculated PDFs without antibiotics were all culture positive; however, when inoculated into antibiotic-admixed PDFs, only S. haemolyticus remained culture-positive ( p < 0.0001). In conclusion, PDF sterility can be maintained using NTAT for up to 3 days at room temperature. Currently, there is insufficient evidence to adopt sterile technique in sterile suites when admixing take-home PDF.

Aim: To explore the associations between protein-bound uraemic toxins (PBTs), fibre intake and patient-focused outcomes in patients on kidney replacement therapy. Background: Despite removal of small water-soluble uraemic toxins, dialysis patients continue to experience high morbidity and mortality. Recent evidence suggests strong associations between PBTs and poorer patient outcomes and symptom burden. Reducing the generation of PBTs by increasing dietary fibre may be an alternate approach to better patient outcomes. Method: This was a cross-sectional study of haemodialysis (HD), peritoneal dialysis (PD) and kidney transplant patients to determine the associations between uraemic toxins [p-cresyl sulfate (PCS) and indoxyl sulfate (IS)], fibre intake and patient-focused outcomes, incorporating the Integrated Palliative Outcome Scale-Renal (IPOS-renal) and EQ-5D-5L to determine symptom burden and quality of life, while physical capacity was determined using the timed up and go(TUG) test and handgrip strength (HGS). Results: Ninety participants completed the study (n = 30 in each group). There was a correlation between PBTs and the IPOS-renal score, where higher toxin levels were associated with a higher symptom burden. This was the strongest for PCS, where the significance remained after accounting for age and co-morbidities (p < 0.05). Higher PBT levels were also associated with lower HGS (p < 0.05). There was a negative correlation between fibre intake and PBTs, serum PCS (r = −0.36, p < 0.05) and serum IS (r = −0.27, p < 0.05). Lower fibre intake was also associated with a higher symptom burden measured by the IPOS-renal (p < 0.05). Transplant patients consistently performed better, with a reduced symptom burden and improved physical ability compared to dialysis patients. Conclusion: PBTs were associated with symptom burden, and lower physical ability was associated with both PBTs and patient-focused outcomes, and this needs to be further investigated in larger studies.