Introduction: Intravenous calcium gluconate has been used to prevent postoperative hypocalcaemia (POH) following parathyroidectomy for secondary hyperparathyroidism in chronic kidney disease (CKD). Materials and Methods: Retrospective data were obtained for 36 patients with CKD stage 4 and 5 after parathyroid surgery, correlating albumin-corrected serum calcium with the infusion rate of calcium gluconate. Calcium flux was characterised along with excursions out of the target calcium range of 2 to 3 mmol/L. With this data, an improved titration regimen was constructed. Results: Mean peak efflux rate (PER) from the extracellular calcium pool was 2.97 mmol/h occurring 26.6 hours postoperatively. Peak calcium efflux tended to occur later in cases of severe POH. Eighty-one per cent of patients had excursions outside of the target calcium range of 2 to 3 mmol/L. Mean time of onset for hypocalcaemia was 2 days postoperatively. Hypocalcaemia was transient in 25% and persistent in 11% of patients. Conclusion: A simple titration regimen was constructed in which a 10% calcium gluconate infusion was started at 4.5 mL/h when serum calcium was <2 mmol/L, then increased to 6.5 mL/h and finally to 9.0 mL/h if calcium continued falling. Preoperative oral calcium and calcitriol doses were maintained. Blood testing was done 6-hourly, but when a higher infusion rate was needed, 4-hourly blood testing was preferred. Monitoring was discontinued if no hypocalcaemia developed in the first 4 days after surgery. If hypocalcaemia persisted 6 days after surgery, then the infusion was stopped with further monitoring for 24 hours.
Transient postoperative hypocalcaemia (POH) is often found following parathyroidectomy for secondary hyperparathyroidism (SHP). When the fall in serum calcium is acute, this can cause neuromuscular irritability which may present as numbness, paraesthesia and cramps. When severe, this may result in bronchoconstriction, cardiac arrhythmias, angina, heart failure and seizures.
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