Analysis of bone metabolism-related parameters in non-dialysis elderly patients with chronic kidney disease

Abstract

Objective To investigate bone metabolism-related parameters in non-dialysis elderly patients with stages 1-5 chronic kidney disease (CKD). Methods A total of 203 elderly patients with stages 1-5 CKD were retrospectively analyzed. Liver and kidney functions, and levels of serum calcium (Ca), serum phosphorus (Pi), parathyroid hormone (iPTH), osteocalcin (OT), β-degradation products of C-terminal telopeptides of type I collagen (β-CTX), 25-dihydroxyvitamin D [25(OH)D], propeptide of type I collagen carboxyl end (PINP) were measured. Results Of the 203 patients, there were 109 males (53.7%) and 94 females (46.3%), and the average age was (72.3±8.2) years. Serum 25 (OH) D levels were lower in females than in males (P<0.01). Serum Ca and 25(OH)D levels gradually declined and serum Pi, iPTH, OT, β-CTX and PINP levels gradually increased with the progression of CKD (all P<0.01). The increase of blood OT, β-CTX, and PINP levels started from stage 3B CKD (all P<0.05). Patients with diabetic kidney disease (DKD) had lower serum levels of OT and 25 (OH) D than patients without DKD (all P<0.01). Univariate correlation analysis showed that the estimated glomerular filtration rate (eGFR) was correlated with serum Ca (r=0.284, P<0.01), serum Pi (r=-0.339, P<0.01), the calcium-phosphorus product (r=-0.245, P<0.01), OT (r=-0.410, P<0.01), β-CTX (r=-0.509, P<0.01), iPTH (r=-0.397, P<0.01), 25(OH)D (r=0.209, P<0.01), PINP (r=-0.434, P<0.01), and age (r=-0.138, P<0.05). Conclusions The increase of serum OT, β-CTX, PINP levels and other bone metabolism-related parameters occurs earlier than symptoms of calcium-phosphorus metabolism disorders in elderly patients with chronic kidney disease, and these parameters can be used for early monitoring of chronic kidney disease-mineral and bone disorders in the elderly. Elderly women with CKD and patients with DKD should be closely monitored on serum 25(OH) D levels. Key words: Kidney disease; Osteocalcin; 25-hydroxyvitamin D 2; Parathyroid hormone