A Simultaneous Determination of the B₁ and B₆ Vitamers Reveals Their Loss During a Single Peritoneal Dialysis...

This study aimed to assess the extent of vitamin B₁ and B₆ vitamer loss during a single peritoneal dialysis (PD) session using a combination of chromatographic techniques and chemometric analysis. Dialysis effluent samples were collected from 41 PD patients (22 on continuous ambulatory peritoneal dialysis (CAPD) and 19 on automated peritoneal dialysis (APD)) during a standardised peritoneal equilibration test. Concentrations of thiamine monophosphate, thiamine diphosphate (ThDP), pyridoxine, pyridoxal (PL), and pyridoxamine were determined using high-performance liquid chromatography with a fluorescence detector. The analytical method was validated in terms of sensitivity, linearity, accuracy, and recovery. Multiple regression analysis was employed to identify potential clinical and demographic predictors of vitamin washout. All vitamers except pyridoxal 5-phosphate (PLP) were detectable in dialysis effluents. ThDP exhibited the greatest loss among the B₁ forms (ca. 0.05-0.57 mg/24 h), while PL exhibited the most significant loss among the B₆ forms (ca. 0.01-0.19 mg/24 h). Vitamin losses varied depending on the dialysis modality (continuous ambulatory peritoneal dialysis, or CAPD, versus automated peritoneal dialysis, or APD) and the peritoneal transport category. Regression analysis identified body weight, haemoglobin, and haematocrit as independent predictors of ThDP washout (R² = 0.58). No statistically robust models were established for the other vitamers. Even short medical procedures (such as single PD) can result in measurable losses of water-soluble vitamins, particularly ThDP and PL. The results emphasise the importance of personalised vitamin supplementation for PD patients and suggest that body composition and haematological parameters significantly influence the loss of thiamine.