Cardiovascular autonomic neuropathy as a cause of fatigue in chronic hypoparathyroidism.

Purpose: Hypoparathyroidism (hypoPT) results in an impairment of quality of life (QoL), an increase in fatigue and a higher risk of mortality. Cardiovascular autonomic neuropathy (CAN) is an impairment of the cardiovascular autonomic system and is associated with increased mortality and fatigability. Patients with hypoPT show an increased risk of CAN. However, no previous studies have investigated the association between CAN and QoL in hypoPT. To test whether CAN is associated with fatigue and impaired QOL in hypoPT patients.

Methods: We enrolled 48 subjects with postsurgical hypoPT treated with calcium and calcitriol and 38 healthy subjects who underwent thyroidectomy. Subjects completed the RAND 36-Item Short Form (SF-36) Health Survey, evaluating physical (PCS) and mental (MCS) health, and fatigue score. CAN was assessed using cardiovascular autonomic reflex tests (CARTs). Participants were considered to have "early CAN" (EC) if they had one abnormal CART and "definite CAN" (DC) with two or more abnormal CARTs.

Results: Compared with controls, hypoPT population had lower fatigue scores (44.5 IQRː9 vs 38.5 IQRː12.3, P = 0.031). In the hypoPT group, only participants with DC had a lower fatigue score than subjects without CAN (DC: β: -9.55, P = 0.005) after adjusting for age, duration of disease, calcium concentration, TSH, calcitriol and calcium supplementation. No differences were found in the PCS and MCS scores in the hypoPT group.

Conclusions: CAN may explain fatigue, a common complaint of postsurgical hypoPT patients. Further larger and prospective investigations are needed to confirm our findings.