Endocrine Abstracts

Introduction: Primary hyperparathyroidism (PHPT) after roux-en-Y gastric bypass (RYGB) is poorly described. The diagnosis can be difficult as secondary hyperparathyroidism(SHPT) commonly occurs in patients after RYGB due to calcium hypoabsorption and vitamin D deficiency.

Observation: We present the case of a 50-year-old female with a history of normocalcemic hyperparathyroidism and nephrolithiasis. In 2005 the patient had undergone RYGB. During the first visit, an iso-hypoechoic nodule below the right inferior pole of the thyroid gland with a maximum size of 47 mm and internal vascularization was detected. Her biochemistry revealed a PTH of 930 pmol/l (18–80 pmol/l), normal levels of total calcium and phosphorus, mild hypoalbuminemia, adjusted calcium of 9.8 mg/dl, hypercalciuria, 25-OH vitamin D levels of 6.4 mcg/l (>30 mcg/l). She was initially treated with 100 000 IU of Vitamin D3 intramuscularly once a month, but calcifediol, a hydroxylated form of vitamin D, was later prescribed due to the patient’s discomfort with the intramuscular injection. Further investigations demonstrated decreased bone density at the hip and distal radius and a single image suggestive for parathyroid adenoma detected by SestaMIBI scintigraphy. The patient underwent parathyroidectomy, and she was discharged with calcium carbonate and calcitriol therapy, but a few days later, she accessed our A&E for hypocalcemia. The hungry bone syndrome was excluded due to her normal phosphorus and magnesium. Histology confirmed a parathyroid adenoma with a maximum diameter of 5 cm. The patient was treated with a single 10% calcium gluconate vial, and subsequently, we preferred to start with calcium citrate supplementation, which is absorbed more efficiently than calcium carbonate. Calcitriol and a protein supplement to treat the persistent patient’s hypoalbuminemia were added. After that, no more severe hypocalcemia episodes occurred, her serum calcium and vitamin D level remained within normal range, PTH levels dropped until 135 pmol/l, and a gradual reduction of the oral supplementation doses was made.

Conclusion: PHPT after RYGB is a rare condition, and concomitant SHPT can make diagnosis and follow-up difficult and predispose patients to more severe postoperative hypocalcemia.