Low PTH May Increase the Risk of Cardiovascular Disease in Hemodialysis Patients
Cardiovascular Disease (CVD) is the leading cause of death in patients on maintenance hemodialysis, and the risk of death from cardiovascular events is 10 times higher than that of the general population. In addition to traditional cardiovascular risk factors, Chronic Kidney Disease - minerals and bone metabolic disorders (CKD-MBD) with high levels of phosphorus, calcium, and secondary hyperparathyroidism (SHPT) are associated with cardiovascular calcification, cardiovascular events, and death.
Previous studies have confirmed that low PTH level is related to all-cause mortality in Dialysis patients. Most dialysis patients have low PTH level, and cardiovascular calcification often occurs in dialysis patients with low PTH level. The 2009 KDIGO guidelines recommended that PTH be maintained at least twice the normal upper limit.
Recently, professor Merle from the United States published the research results of the effect of low PTH on cardiovascular mortality and all-cause mortality as well as the influencing factors of low PTH level in patients with hemodialysis in the journal Kidney International.
The researchers conducted a prospective, multicenter observational study, which included a total of 3,030 patients tested for iPTH in October 2010. At the 12th month, 1983 patients with total parathyroid hormone (iPTH) were observed and detected, whose average age is 67.9 ± 15.4 years old. From the 12th month to 24th month, 250 patients (12.6%) died, of which 105 cases (42%) died of CV and 145 cases (58%) died from non-CV causes.
Through Cox regression analysis, there was no independent correlation between the low iPTH level at enrollment or the 12th month and all-cause mortality from the 12th month to the 24th month. However, low iPTH at enrollment and at the 12th month did not increase the risk of cardiovascular death. On the contrary, patients with normal or high iPTH at enrollment and low iPTH at the 12th month increased the risk of cardiovascular death by 2 times. Patients with low iPTH at enrollment or 12th month were not found to be associated with increased non-cardiovascular mortality, while low iPTH at enrollment and low iPTH at 12th month were associated with non-cardiovascular mortality at 24 months of follow-up at enrollment.
Predictors of PTH changes: low levels of plasma albumin increased the risk of PTH transition from high or normal levels to low levels, high-calcium dialysate greater than 1.75 mmol/L, high-dose inactive vitamin D, and calcium-phosphate binders also increase the transition risk, while non-calcium-phosphate binders reduce the risk of PTH reduction.
The predictors of cardiovascular mortality in patients with high or normal PTH levels transiting to low PTH were age, CPR>10 mg/L, high calcium (>1.75 mmol/L) dialysate and cardiovascular mortality, while no association was found between high calcium dialysate and cardiovascular mortality in patients with sustained low PTH levels.
The shortcomings of this study
1. In this study, iPTH was suggested to be controlled according to the KDIGO guidelines, so the enrolled population may have better control of secondary hyperparathyroidism (SHPT) or even overtreatment.
2. Some clinical test data are imperfect, such as indicators of residual renal function and serum magnesium; Some of the treatment measures were poorly documented, such as inaccurate dosing changes and unknown dialysate composition.
3. This study only analyzed the relevant indicators of dialysis patients, but did not study the results of these studies at different stages of dialysis.
Summary on the results of this study
1. This study is consistent with previous studies that most patients on maintenance hemodialysis have low PTH status.
2. This study found that low PTH status was an independent risk factor for cardiovascular death.
3. Low PTH status caused by high calcium dialysis will increase the risk of cardiovascular death in dialysis patients, so high calcium dialysis fluid should be used carefully.
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