Secondary Hyperparathyroidism in Obese Patients Post Sleeve Gastrectomy

Bariatric surgery provides an effective option for the management of morbid obesity. Several studies have investigated the association between bariatric surgery and secondary hyperparathyroidism (SHPT). This study aims to compare the levels of blood biomarkers, specifically, calcium (Ca), vitamin D, and phosphate (PO4), and their association with parathyroid hormone (PTH) levels pre- and post-bariatric surgery. In addition, it aims to assess the prevalence of hyperparathyroidism post-bariatric surgery in a tertiary care hospital in Saudi Arabia.

A prospective cohort study was conducted at a large tertiary care hospital between May 2017 and April 2019. The study included adult obese patients who underwent laparoscopic sleeve gastrectomy (LSG). Patients were excluded if they were known to have any comorbidities, receiving vitamin supplements, and those who had undergone bariatric procedures previously. Routine blood tests, including PTH, vitamin D, Ca, and PO4, were collected at baseline, and post-surgery.

A total of 143 patients who underwent LSG were included in the study. Hyperparathyroidism was observed in 15.4% of patients at baseline and in 36.4% of patients' post-surgery (p < 0.001). Low vitamin D levels, which were highly prevalent before surgery, decreased sustainably (66.4% pre-operative and 28% at follow-up after surgery, P=0.032). Baseline hypocalcemia was observed in 20.3% of patients compared to 8.4% post-surgery (P=0.546). Hypophosphatemia was present in 60.8% of subjects at baseline, while the percentage dropped to 21.7% post-surgery. There was a significant association between PO4 and PTH levels at baseline. Post-operatively, there was a significant correlation between PTH and both vitamin D and calcium levels.

Our study showed that the higher levels of PTH post LSG can be related to vitamin D deficiency and lower calcium levels, despite patients following the provided recommendations for supplementation. This study also emphasizes the importance of routine testing for hyperparathyroidism both before and after bariatric surgery.