Changes of abdominal aortic calcification after parathyroidectomy in maintenance hemodialysis patients

Objective To observe the changes of abdominal aortic calcification and biochemical indicators after parathyroidectomy (PTX) in the maintenance hemodialysis (MHD) patients with secondary hyperparathyroidism (SHPT). Methods The MHD patients with SHPT who were followed up for 2 years were analyzed retrospectively and divided into PTX surgery group (n=26) and non-surgery group (n=18) according to whether they underwent PTX, and then the abdominal aortic calcification score (AACS), intact parathyroid hormone (iPTH), blood calcium and phosphorus after 2 years were observed in the two groups. The PTX surgery group was divided into advanced group and non-advanced group according to whether abdominal aortic calcification had progressed or not 2 years after the operation. Indicators such as age, dialysis age, iPTH, blood calcium, blood phosphorus, calcium and phosphorus product were compared between the two groups to analyze the possible factors related to the development of abdominal aortic calcification. Results A total of 44 patients meeting the inclusion criteria were included, with 26 in the PTX surgery group and 18 in the non-surgery group. The baseline data of the PTX surgery group and the non-surgery group showed statistical difference in the age of dialysis (P<0.05), but no statistical differences in gender, age and history of hypertension. Compared with preoperative indicators, postoperative iPTH, blood calcium and phosphorus significantly reduced (all P<0.05), and there was no significant difference in AACS. There were 8 cases (30.77%) of accelerating progress of calcification, 8 cases (30.77%) of improvement in calcification, 10 cases (38.46%) of calcification stability. After 2 years, iPTH value of non-advanced group was significantly lower than advanced group [(20.62±6.44) ng/L vs (132.72±76.83) ng/L], while the preoperative AACS progress was higher in non-advanced group [(13.11±2.71) vs (2.00±1.41)] (all P<0.05). In non-surgery group, AACS was significantly higher after 2 years [(10.44±1.65) vs (8.05±1.26)], blood phosphorus and the product of blood calcium and phosphorus significantly decreased (all P<0.05) , and the levels of iPTH and blood calcium did not significantly change. Pearson correlation analysis showed that the decreased value between preoperative AACS and 2-year postoperative AACS was positively correlated with the decreased value of iPTH (r=0.534, P=0.012), blood calcium (r=0.643, P=0.004), blood phosphorus (r=0.897, P<0.001) and calcium-phosphorus product (r=0.568, P=0.021) , and negatively correlated with preoperative AACS (r=-0.647, P=0.014). Conclusions Small sample data shows that PTX can correct parathyroid hormone, calcium and phosphorus for long term, and prevent abdominal aortic calcification progression, even reverse vascular calcification. Whether abdominal aortic calcification improves or not may be associated with the decrease of iPTH, calcium, phosphorus and the product of blood calcium and phosphorus. Key words: Parathyroidectomy; Renal dialysis; Aorta, abdominal; Vascular calcification