Serum PTH Associated with Malnutrition Determined by Bioelectrical Impedance Technology in Chronic Kidney Disease Patients.

Abstract

Purpose Chronic malnutrition and cachexia are common in chronic kidney disease (CKD), and importance should be given to these complications because they affect the patient's quality of life and prognosis. This study analyzed the correlation between the serum PTH level, nutritional status, and body composition of patients with CKD. Methods CKD patients were enrolled in Center for Kidney Disease, Second Affiliated Hospital of Nanjing Medical University, from December 1, 2016, to November 30, 2020. Bioelectrical impedance technology was applied to estimate the body composition. The characteristics of the body composition were compared among different stages of CKD patients, and then the correlation between PTH and body composition was analyzed. Results 205 CKD patients were enrolled. Twenty-five patients were in stage 1 or 2 of CKD, 78 patients were in stage 3 or 4, 31 patients were in stage 5 without dialysis (referred to as CKD stage 5A), and 71 patients were in stage 5 with dialysis (referred to as CKD stage 5B). Body composition analysis showed that the patients had a phase angle (PA) of 5.02 ± 1.07°, a percentage of body fat (PBF) of 27.74 ± 8.8%, and a skeletal muscle mass index (SMI) of 7.4 ± 1.34 kg/m2. PBF peaked in the CKD stage 3/4 group and gradually decreased with the progression of CKD. The PA and SMI differed significantly between the CKD stage 1/2 and stage 5B groups. The proportion of low SMI did not differ significantly between the CKD stage 1/2 and stage 3/4 groups, but it was obviously higher in the CKD stage 5A and 5B groups. PTH was significantly correlated with BMI, hemoglobin, albumin, total cholesterol, triglycerides, and SMI. Binary logistic regression of low SMI showed that the odds ratio for PTH levels was greater than the upper limit of the normal range, which was 11.769 (p=0.043, 95% confidence interval: 1.078–128.536), and the model predictive power was 0.986 after correction for age, sex, height, weight, hemoglobin, serum calcium, serum phosphorus, serum total cholesterol, serum triglyceride, and basal metabolic rate. Conclusions Bioelectrical impedance analysis might be useful in estimating the nutritional status of CKD patients in terms of fat and muscle parameters. High levels of PTH are an independent risk factor for developing low SMI in CKD patients.