Abstract: Objective  To investigate the control target of intact parathyroid hormone (iPTH) level in patients with non-dialysis-dependent chronic kidney disease (CKD).  Methods  The CKD patients with complete blood and urine biochemical results, not received renal replacement therapy and treated in the Outpatient/Inpatient Sections, Department of Nephrology, Peking University People's Hospital from March 2016 to October 2022 were recruited. The relationship between estimated glomerular filtration rate (eGFR), iPTH and fraction excretion of phosphate (FEP) in these patients were investigated. By using the segment function in R language, the iPTH-FEP fitting curve is depicted to find out the truncate point that FEP increases no longer with the increase of iPTH.  Results  A total of 125 subjects were enrolled in this study. When eGFR was <60 ml / min·1.73m2, iPTH and FEP levels gradually increased with the decline of renal function. When iPTH >114.74pg/ml, FEP no longer increased.  Conclusion  When iPTH increased to more than 114.74pg/ml in non-dialysis-dependent CKD patients, the ability to promote renal excretion of phosphorus reached the maximum.

Key words: Chronic kidney disease, Urinary phosphorus excretion fraction, Parathyroid hormone