Body Composition in Primary Hyperparathyroidism: A Potential Contributor to Weakness and Fatigue

Abstract

Background Primary hyperparathyroidism (PHPT) patients commonly report weakness and fatigue, though the underlying mechanisms are uncertain. Our purpose is to determine whether CT-derived muscle and adipose tissue metrics are associated with weakness and fatigue in PHPT patients. Methods For this retrospective study, cross-sectional muscle and adipose tissue metrics were derived from CTs in PHPT patients undergoing preoperative imaging within 1 year of parathyroid surgery. Skeletal muscle index (SMI) and visceral adipose tissue (VAT)/subcutaneous adipose tissue (SAT) ratio were calculated based on a single CT image at the level of the L3 vertebra. Established sex-specific SMI thresholds were used to define sarcopenia. Demographic and clinical data were collected from the electronic health record. When available, postoperative CT images were analyzed to assess for changes in body composition pre- and post-parathyroidectomy. Results The cohort comprised 53 PHPT patients (38 females, 15 males, mean age 61.4 years), of whom 24 (45%) reported weakness, 43 (81%) reported fatigue, and 31 (58%) met CT-based criteria for sarcopenia. Lower SMI was significantly associated with preoperative weakness in females but not males. For both weakness and fatigue, VAT/SAT ratios were higher in symptomatic females and lower in symptomatic males than their asymptomatic counterparts, though these differences were not statistically significant. In patients with postoperative CTs (n = 23), no significant changes in CT metrics were observed after parathyroidectomy. Discussion In females but not males with PHPT, subjective preoperative weakness was significantly associated with lower SMI. Effects of parathyroid hormone on skeletal muscle and visceral adiposity may differ by sex.