The correlation of heart rate variability with parathyroid hormone in hemodialysis patients with secondary hyperparathyroidism

Introduction: Hyperparathyroidism (HPTH) which is often found in end stage of chronic renal disease patients replaced by hemodialysis (HD) may cause the cardiac autonomic neuropathy. Method: Healthy subjects and HD patients categorized into two groups by parathyroid hormone (PTH) levels: high PTH group (H-PTH; PTH = 150 300 pg/mL) and ultra high PTH group (UH-PTH; PTH > 300 pg/mL) were investigated. Frequency and time domains of heart rate variability (HRV) were analyzed. The frequency domain parameters were then transformed by the fast Fourier transform and its normalized unit was calculated in terms of natural logarithms (ln). The correlations between PTH concentration and each parameter of HRV were analyzed by Pearson’s correlation. Result: The results of the current study showed that frequency and time domains of UH-PTH were at lowest values. The values of lnTP (total power), lnLF (low frequency), LF/HF ratio (low frequency and high frequency ratio), SDANN (standard deviation of the averages of N-N intervals in all 5-minute segments), SDNN (standard deviation of N-N intervals), TINN (triangular interpolation of N-N interval) and HRV index, were significantly lower in UH-PTH compared to H-PTH. Moreover, lnLF showed the highest negative correlation with lnPTH concentration. This correlation coefficient (r) was -0.633. Discussion and The greatest reduction in LF and SDNN, and the highest negative correlation between lnLF and lnPTH Conclusion: indicated that the sympathetic nervous system was, at least in part, activated by hyperparathyroidism. It is suggested that PTH plays a role as an important uremic toxin which involves in the initiation of cardiac sympathetic hyperactivity.