Endocrine Abstracts

Background: Primary hyperparathyroidism may severely manifest with an adjusted calcium >3.5mmol/l and increased risk of prolonged postoperative hypocalcaemia. Formal consensus on preoperative optimisation appears lacking, especially around the utility of parenteral bisphosphonate treatment. Bisphosphonate therapy has been demonstrated to cause prolonged hypocalcaemia when given to patients with a history of parathyroidectomy.

Methods: We retrospectively evaluated records of 21 patients, over a four-and-a-half-year period. All presented with severe primary hyperparathyroidism (adjusted calcium ≥ 3.5mmol/l). Anaesthetic risk at such high levels of adjusted calcium is markedly increased with many anaesthetists reluctant to give a general anaesthetic. Thus far, there are few data exploring the preoperative use of bisphosphonates to bring calcium levels to a safe range for administration of anaesthesia. We report the outcomes of preoperative interventions and evaluate the outcomes, namely risk of postoperative hypocalcaemia.

Results: Seventeen patients received at least one standard dose of intravenous pamidronate preoperatively as therapy for hypercalcaemia (8 patients were given this within 10 days of parathyroidectomy). Pamidronate disodium was effective in lowering calcium and appeared safe when administered preoperatively. No patient developed severe or prolonged postoperative hypocalcaemia. Furthermore preoperative 25-(OH)D insufficiency/deficiency was highly prevalent. No patient that had undergone adequate vitamin D repletion developed severe postoperative hypocalcaemia (<1.9mmol/l).

Conclusion: Pamidronate disodium appears safe when given to correct hypercalcaemia in severe disease (adjusted calcium ≥ 3.5mmo/l) preoperatively to reduce anaesthetic risk. Therefore, parenteral bisphosphonate therapy should be considered to facilitate surgery. Preoperative vitamin D replacement is standard practice in patients undergoing parathyroidectomy. We have demonstrated that it can be given to patients safely despite baseline adjusted calcium levels ≥ 3.5mmol/l. Indeed, ensuring vitamin D is replete preoperatively may have an impact on preventing postoperative hypocalcaemia in our cohort of patients.