A Novel Equation for Estimating Sodium Intake in Peritoneal Dialysis.

Dietary sodium intake is closely associated with the prognosis of chronic kidney disease (CKD) patients. Previous studies have developed an equation for estimating dietary sodium intake through 24-hour urine sodium in CKD, which are not applicable in peritoneal dialysis patients. This study aims to develop a novel equation for estimating dietary sodium intake in 20 anuric peritoneal dialysis patients, using accurately measured dietary sodium as the dependent variable and peritoneal sodium removal and its related variables as independent variables, and then to validate the precision and accuracy of the novel equation in another 10 anuric peritoneal dialysis patients.

Primary outcomes

• determination coefficient of the novel equation [July 3, 2023, to March 1, 2024]: Determination coefficient will be assessed as the square of the multiple correlation coefficient of the novel equation for estimating sodium intake in peritoneal dialysis.
• bias of the novel equation [July 3, 2023, to March 1, 2024]: Bias will be assessed as the median of the difference between the estimated and measured dietary sodium values.
• precision of the novel equation [July 3, 2023, to March 1, 2024]: Precision will be assessed as the standard deviation (SD) for the absolute value of difference between the estimated and measured dietary sodium values.
• accuracy of the novel equation [July 3, 2023, to March 1, 2024]: Accuracy will be assessed as the percentage of estimates that differed >20% from the measured dietary sodium values (1-P20) .

Sex: All, ages: 18 Years to 80 Years

Inclusion Criteria:

* Peritoneal dialysis vintage >3 months.
* 18-80 years old.
* No residual renal function (urine volume<200ml/day).

Exclusion Criteria:

* Peritonitis in the past month.
* Acute systemic infection, cardio-cerebrovascular complications and surgical trauma in the past month.
* Uncorrected hyponatremia (blood sodium<130mmol/L).
* Prescribed with sodium bicarbonate.
* Prescribed with glucocorticoids and aldosterone antagonists.
* Dysfunction of peritoneal dialysis catheter.
* Malignant tumor receiving radiotherapy and chemotherapy, severe dyspepsia or eating disorder.
* Body fluid loss due to vomit, diarrhea, massive sweating, or other causes.
* Cannot follow the research scheme.
* Refuse to participate in this study.

• Jie Dong, Professor, Principal investigator, Peking University First Hospital