Regarding the 6 patients with POD1 PTH ≥ 15 pg/ml and calcium ≥ 2.0 mmol/l who went on to develop symptomatic hypocalcaemia, 3 were undergoing surgery for Graves disease, one had a history of Graves disease, and one was undergoing surgery for non-Graves hyperthyroidism. Here, PTH is linked to Hypocalcemia.