Background and aim: The optimal approach to detect and treat symptomatic hypocalcemia (SxH) after thyroidectomy is still uncertain. In our retrospective study, we sought to set a standardized postoperative management protocol on the basis of relative change of parathyroid hormone (PTH) and absolute value of postoperative day 1 (POD1) PTH.
Methods: Patients who underwent thyroidectomy were identified retrospectively in our prospective database. Blood was collected 1 day before surgery and on POD1. Extra calcium and calcitriol supplement was prescribed when necessary. Meanwhile, postoperative signs of SxH were treated and recorded in detail. Patients were followed up for 1 month after surgery and then 3 months thereafter.
Results: A total of 744 patients were included in the final analysis. Transient SxH occurred in 86 (11.6%) patients, and persistent SxH occurred in 4 (0.54%) patients in more than half year after surgery. Relative decrease of PTH reached its maximal discriminative effect at 70% (area under the curve [AUC] =0.754), with a sensitivity of 72.1% and a specificity of 75%. In Group 1 (≤70%), 24 (4.67%) patients were interpreted as having SxH, whereas in Group 2, 62 (27.0%) patients had SxH (>70%), P <0.001. Days of symptom relief in Group 1–1 (1, 2) were significantly shorter than those in Group 2–2 (1, 10), P =0.023. In Group 2, 112 (80%) patients with POD1 PTH <1 pmol/L were treated with calcitriol, whereas only 8 (8.89%) patients with POD1 PTH ≥1 pmol/L were treated with calcitriol (P <0.001). According to relief of SxH and recovery of parathyroid function, treating with and without calcitriol showed no difference in patients with POD1 PTH <1 and ≥1 pmol/L.
Conclusion: Relative decrease of PTH >70% is a significant risk factor for SxH in post-thyroidectomy. The decreasing percent of PTH ≤70% ensures discharge on POD1, but longer hospitalization was advocated for patients with decreasing percent of PTH >70%, who needed extra calcitriol supplement when POD1 PTH <1 pmol/L.
Keywords: parathyroid hormone, PTH, relative change, thyroidectomy, calcitriol, discharge