P1415PARATHYROIDECTOMY IMPROVES MUSCULAR FUNCTION BUT NOT MUSCLE MASS IN HEMODIALYSIS PATIENTS WITH SEVERE HYPERPARATHYROIDISM

Abstract

Abstract Background and Aims Increased levels of parathyroid hormone (PTH) are associated with a negative impact on the bone-muscle axis including sarcopenia with muscle weakness and muscle atrophy and osteoporosis, and it is possible that treating hyperparathyroidism (HPT) can ameliorate these disturbances. However, the effects of parathyroidectomy (PTX) on muscle mass, strength and performance, and physical activity have not been thoroughly investigated. This study aims to evaluate the impact of PTX on muscle (mass, strength, and performance), physical activity, body fat and resting energy expenditure (REE) in patients on hemodialysis with severe HPT. Method We are prospectively evaluating muscle mass strength, performance and physical activity of 30 patients before and after 6 months of PTX by using Actigraph GT3X accelerometer, timed-up-and-Go (TuG), Sit-to-Stand-to-Sit (STS) and muscle strength tests [handgrip (HGS), supine (SP) and leg press (LP)]. Body composition changes were assessed by dual-energy x-ray absorptiometry (DXA), and REE was examined by indirect calorimetry. Results At 6 months after PTX, 11 patients who already completed the protocol, showed a significant drop in PTH [1445 (1363-1937) vs. 54 (23-132) pg/mL; p = 0.002] and alkaline phosphatase [306 (235-744) vs. 77.5 (52-100] U/L); p = 0.002], a significant increase of number of steps/day [4321 (3384 – 6317) vs. 5950 (3918 – 7159); p = 0.04] and improvements of strength tests: HGS (27 ±14 vs. 31 ±15 kg; p = 0.01); SP (27 ±15 vs. 31 ±17 kg; p = 0.01] and LP [27 (2-36) vs. 36 (24-89) kg; p 0.04]. In addition, there was a significant reduction of TuG [10 (8-15) vs. 8 (7-11) seconds; p = 0.01], and a tendency towards STS improvement [6 (0-7) vs. 8 (7-11); p = 0.06]. A significant increase in body weight (66 ± 12 vs. 68 ± 14 Kg; p = 0.02), body mass index [24 (21–26) vs. 26 (21–28) kg/m2; p 0.001], and bone mineral content (BMC) [1.8 (1.3-2) vs. 2.1 (1.7-2.7); p=0.002] was seen. However, lean body mass (LBM) decreased [40.4 (38-55) vs. 39 (37-51) Kg; p=0.001], whereas fat mass (FAT) increased [18 (17-28) vs. 24 (17–30) kg; p = 0.02]. No change was noted in skeletal muscle index (SMI) and in REE [1580 (1193–1988) vs. 1473 (1326 - 1786) kcal/day; p = 0.7). We noticed a tendency toward an increase in IGF-1 levels [180 (141-207) vs. 223 (151-281) µg/L; p = 0.08], but no significant variation was found in serum albumin, insulin and HOMA index. Conclusion In hemodialysis patients with secondary hyperparathyroidism undergoing PTX, there were marked improvements of muscular function and bone mass, but not of muscle mass. Our findings suggest that PTH-associated sarcopenia is mediated not only by a decrease in muscle mass but also by muscle dysfunction. The long-term effect of PTX on muscle status remains to be further examined.