V. Lai1, K. D. Burman2 1Virginia Hospital Center,Arlington, VA, USA 2MedStar Washington Hospital Center,Washington DC, WASHINGTON, DC, USA
Introduction: Primary hyperparathyroidism (1HPT) affects 1-3% of the population and can negatively impact bone mineral density (BMD), with an increased risk of osteoporosis and fractures. A much higher percentage of the population has obesity, and rates of Roux-en-Y gastric bypass (RYGB) surgery to correct morbid obesity has increased. Some have noted that RYGB patients may develop lower BMD, especially at the femur. Secondary hyperparathyroidism (2HPT) in RYGB patients is common, but 1HPT in RYGB patients has not been well studied, particularly studies of their bone health. The aim of the study was to compare the BMD of RYGB patients who develop 1HPT to those with 1HPT who have not undergone RYGB. The hypothesis was that patients with 1HPT and a history of a RYGB would have lower BMD than controls.
Methods: A retrospective review of adult patients with sporadic 1HPT cared for within a multi-site metropolitan health network between 2000-2018 was performed. Patients with a history of RYGB and 1HPT were identified with ICD and CPT codes, and included if they had BMD data from dual-energy x-ray absorptiometry scans. Cases were matched 1:1 by age, race, and sex to a control group of patients with 1HPT without a history of RYGB. BMD, biochemical, and clinical data were collected.
Results: Four patients with a history of RYGB who developed 1HPT were identified: 100% were female; 50% were white and 50% were black; the average age at the time of 1HPT diagnosis was 61 years. The cohort was more likely than the controls to have osteoporosis (75% vs. 25%) and less likely to have any one site with normal BMD (0% vs. 100%). The worst BMD occurred in the distal radius and lumbar spine in the cohort group, and in the lumbar spine in the control group. Fractures occurred in 50% of both. The patients with a history of RYGB with 1HPT tended to have lower serum calcium and higher parathyroid hormone (PTH). Both groups were vitamin D replete, and the RYGB group was more likely to have taken high-dose supplementation (75% vs. 25%) to achieve vitamin D repletion. All patients in the cohort group underwent parathyroidectomy without significant complications, and with postoperative normalization of serum calcium and PTH.
Conclusion: Patients with 1HPT who have undergone RYGB may present with worse BMD than those with 1HPT who have not undergone RYGB. The distribution of the bone disease in the patients with 1HPT and a history of RYGB seemed more similar to the pattern of bone disease of typical 1HPT patients than in typical post-RYGB patients, where changes occur in the femur. They were more likely to have required high-dose supplementation to be vitamin D replete, and they had lower serum calcium and higher PTH levels, which may reflect the influence of 2HPT to the 1HPT picture. Whether this contributed to the BMD results is possible, and further study on the bone health of these patients would help clarify the results of these initial findings.