Predictive Factors of Secondary Normocalcemic Hyperparathyroidism after Roux-en-Y Gastric Bypass

OBJECTIVE: Aim of this study is to evaluate determinants of secondary normocalcemic hyperparathyroidism (SNHPT) persistence in patients who have undergone Roux-en-Y gastric bypass on vertical-banded gastroplasty. METHODS: 226 consecutive patients submitted to bariatric surgery were prospectively enrolled and divided in two groups on the basis of preoperative presence of SNHPT. For each patient, we evaluated anthropometric and laboratory parameters. Calcium metabolism (calcemia, PTH, and 25-hydroxy vitamin D serum levels) was studied before surgery and at 6-month intervals (6, 12, and 18 months) as surgical follow-up. RESULTS: Based on presurgical SNHPT presence or absence, we defined group 1—201 patients and group 2—25 patients, respectively. Among the group 1, 153 (76%) recovered from this endocrinopathy within 6 months after surgery (group 3), while the remaining 48 patients (24%) had persistent SNHPT (group 4). Comparing the anthropometric and laboratory data of group 3 with group 2, the only statistically significant factor was the elapsed time since a prior effective medically controlled diet that led to a steady and substantial weight loss. We found also a statistically significant difference (p < 0.05) between group 3 and group 4 in term of % of weight loss and PTH levels. CONCLUSIONS: Patients suitable for bariatric surgery must have history of at least one efficient medically controlled diet, not dating back more than 5 years before surgery. This elapsed time represent the cut-off time within which it is possible to recover from SNHPT in the first semester after Roux-en-Y gastric bypass on vertical-banded gastroplasty. The treatment of vitamin D insufficiency and the evaluation of SNHPT before bariatric surgery should be recommended. The clinical significance of preoperative SNHPT and in particular SNHPT after bariatric surgery remains undefined and further studies are required.