PTH and Hypocalcemia: In a randomized study comparing US with conventional clamp‐and‐tie haemostasis in 778 patients in China20, operating time was significantly lower with US (79 versus 125 min), and mean parathyroid hormone and calcium levels on day 1 were lower in the clamp‐and‐tie group, but the differences were not statistically significant and there was no difference in the rates of transient hypocalcaemia.