Background Conventional treatment for hypoparathyroidism relies on gastrointestinal absorption of oral calcium and calcitriol. Challenges in managing post-thyroidectomy hypocalcaemia in patients with a history of bariatric surgery and malabsorption have been described (1, 2), but postoperative management of bariatric surgery in patients with established hypoparathyroidism has not.
Case A 46-year-old woman underwent elective sleeve gastrectomy. Past history included iatrogenic hypoparathyroidism and hypothyroidism following total thyroidectomy 20 years earlier in 1999 for multinodular goitre, and psoriatic arthritis on immunosuppression. The operation was complicated by multiple gastric perforations necessitating emergency Roux-en-Y gastric bypass. The patient developed abdominal sepsis and was transferred to a tertiary centre. Four days post-operation, having remained nil orally, the ionised calcium level was 0.78 mmol/L (1.11-1.28 mmol/L) without seizure or arrhythmia, and continuous intravenous calcium infusion via central line was necessary to achieve normocalcaemia. Intravenous calcium gluconate 4.4 mmol 6-hourly was continued for 6 months during sepsis and debridement until oral intake was restored. Intravenous calcitriol twice-weekly reduced calcium requirement and provided relative bone protection. Euthyroidism was achieved with intravenous levothyroxine.
Discussion Calcium replacement is complicated when enteral absorption is impaired. Available non-oral options for treatment of hypoparathyroidism will be presented alongside cost analysis. Subcutaneous recombinant human PTH 1-34 (teriparatide) and PTH 1-84 (natpara) are now approved in the USA for hypoparathyroidism, and are recommended in cases of malabsorption (3-5). Strategies to improve enteral absorption of calcium and calcitriol post bariatric surgery such as escalating doses, gastrostomy tube insertion and pancreatic enzyme supplementation have been successfully trialled (6, 7).
Conclusion We propose careful consideration be given before bariatric surgery in patients with pre-existing hypoparathyroidism, due to difficulty in managing hypocalcaemia with impaired gastrointestinal absorption, which is exacerbated when complications occur. Approval of subcutaneous recombinant PTH for hypoparathyroidism in Australia will alter future management.