Correlation analysis between serum miR-29b level and parameters of mineral and bone metabolism disorders in patients on maintenance hemodialysis

Objective  To explore the correlation between serum microRNA（miR）-29b level and chronic kidney disease-mineral and bone metabolic disorder（CKD-MBD） parameters in maintenance hemodialysis（MHD） patients.

Methods  From February 2019 to November 2021, 116 patients with regular MHD at our blood purification center were selected as MHD group. According to the range of serum calcium, phosphorus and intact parathyroid hormone（iPTH）, they were assigned into two groups of target（without CKD-MBD） and non-target（with CKD-MBD）. Also 116 healthy subjects were included into control group. The levels of serum miR-29b, calcium, phosphorus, iPTH, hemoglobin（Hb）, alkaline phosphatase（ALP）, albumin（Alb）, β2 microglobulin（β2-MG） and 25-hydroxyvitamin D25（OH）D were detected and inter-group differences compared. Pearson’s method was employed for examining the correlation between miR-29b and various clinical parameters in substandard group. Logistic regression was utilized for examining the related influencing factors of miR-29b reduction.

Results  In MHD group, phosphorus（1.50 ± 0.37）mmol/L vs （1.12 ± 0.26）mmol/L, ALP（96.07 ± 13.54） U/L vs （72.39 ± 11.95） U/L, β2-MG（1.73 ± 0.51）mg/L vs （1.48 ± 0.36）mg/L, 25（OH）D（21.30 ± 5.47）μg/L vs （16.82 ± 3.15）μg/L, iPTH（325.08 ± 84.90） ng/Lvs （50.74 ± 9.36）ng/L were higher than those in control group; the expression levels of Hb（114.93 ± 7.26）g/L vs （125.74 ± 10.51） g/L, Alb（37.25 ± 3.82）g/L vs （43.18 ± 4.04）g/L and miR-29b（0.72 ± 0.15） vs （1.06 ± 0.12） were lower than those of control group. And the difference was statistically significant （P＜0.05）. Nine of them（7.76%） simultaneously attained the target values of calcium, phosphorus and iPTH specified within the CKD-MBD guidelines. The expression level of serum miR-29b in standard group（0.92 ± 0.17） was greatly higher than that in non-standard group （0.70 ± 0.15） and the difference was statistically significant（P＜0.05）. A negative correlation existed between miR-29b and 25（OH）D, phosphorus and iPTH in substandard group（r = −0.592, −0.546, −0.601, all P＜0.05）. However, there was no correlation with age, body mass index, dialysis time, Hb, ALP, Alb calcium or β2-MG（all P＞0.05）. 25（OH）DOR（95%CI）: 1.627（1.110-2.384）, phosphorusOR（95%CI）: 1.461（1.064-2.007） and iPTHOR（95%CI）: 1.539（1.092-2.169） were the risk factors for a decline of miR-29b（P＜0.05）.

Conclusion  Down-regulated in MHD patients with mineral and bone metabolism disorders, MiR-29b is correlated negatively with 25（OH）D, phosphorus and iPTH.