Endocrine Abstracts

Bariatric surgery significantly reduces obesity-related comorbidities. Secondary hyperparathyroidism (SHPT), due to calcium malabsorption and vitamin D deficiency, has been frequently reported, however, in patients after bariatric surgery. Whether chronic SHPT after bariatric surgery could ultimately evolve into tertiary hyperparathyroidism has not been clarified. Here, we report a 59-old-woman who presented with osteoporosis (T score at the lumbar spine -4.1 and T score at the distal radius -2.5). Mild primary hyperparathyroidism (PHPT) was documented in the laboratory work up: total calcium 2.65 mmol/ l (normal ranges 2.15-2.55 mmol/l) and parathyroid hormone (PTH) 8.9 pmol/l (normal ranges 1.58-6.03 pmol/l). MIBI scintigraphy revealed a left upper enlarged parathyroid gland which was removed. Histopathology was reported as parathyroid hyperplasia. Postoperatively, hypercalcemia persisted. The patient then underwent PET-CT with fluorocholine which showed weak activity in the left lower parathyroid gland. An enlarged parathyroid gland was not, however, found during the second surgery. The patient underwent left hemithyroidectomy to remove a potential intrathyroidal parathyroid gland but none was seen on postoperative histopathology and hypercalcemia continued. The patient had a history of laparoscopic gastric banding for obesity 10 years prior to her presentation with PHPT. To reduce hypercalciuria and to improve calcium absorption, hydrochlorothiazide and vitamin D supplementation were started, followed by oral ibandronate. After a year of treatment bone mineral density at the lumbar spine significantly improved (by 22%) whereas serum calcium and PTH have not changed. Although we do not have a histologic correlate, a combination of inaccurate parathyroid imaging, multiglandular parathyroid disease and complicated parathyroid surgery together with a significant bone mineral density improvement might be indirectly suggestive of tertiary hyperparathyroidism in a patient with a history of bariatric surgery. Longstanding SHPT may contribute to the development of hypercalcemic, i.e. tertiary, hyperparathyroidism. In a patient presenting with hypercalcemic hyperparathyroidism and a history of bariatric surgery, multiple parathyroid gland disease with tertiary hyperparathyroidism should be considered. Supported by MH CZ - DRO (Institute of Endocrinology - EÚ, 00023761).