Changes and Influencing Factors of Urinary Phosphorus Excretion in Patients with Different Stages of Chronic Kidney Disease.

Background: The aim of the study was to explore the changes and the possible influencing factors of phosphorus excretion in chronic kidney disease (CKD) patients.Methods: A database with 204 patients who met the CKD diagnostic criteria was established. Clinical data, includ-ing 24-hour urine phosphorus excretion (24-hour UPE), were collected. The demographic and clinical characteris-tics of CKD patients in different stages and the changes in serum phosphorus (P) and 24-hour UPE with renal function were studied. After exploring the factors influencing 24-hour UPE by multiple linear regression analysis, the effects of gender on 24-hour UPE was assessed.Results: Among 204 patients, there were significant differences in serum calcium (Ca), P, 24-hour UPE, intact parathyroid hormone (iPTH), and 25-hydroxyvitamin D [25(OH)-VD] among different CKD stages. Twenty-four-hour UPE fluctuated greatly, but serum P was relatively stable, which was > 1.46 mmol/L at an estimated glomer-ular filtration rate (eGFR) < 10 mL/minute/1.73 m2. Male gender (t) = 3.42, p < 0.00) and eGFR (t) = 0.06, p < 0.00) were related to 24-hour UPE, while age, body weight, albumin (ALB), iPTH, and serum P were not related to 24-hour UPE according to regression analysis. There were significant differences in 24-hour UPE and serum P be-tween males and females.Conclusions: Urinary phosphorus excretion decreased with decreasing renal function in CKD patients. Urinary phosphorus excretion might be affected by eGFR and gender. (Clin. Lab. 2023;69:xx-xx. DOI: 10.7754/Clin.Lab.2022.220422)