Objectives: Post-surgical hypoparathyroidism (PoSH) is a common long-term complication after thyroid surgery. The reported median incidence rates of temporary and permanent PoSH was 27% and 1% respectively.
Methods and results: We retrospectively analyzed the files of 552 patients who underwent thyroidectomy in our surgery department between 2015 and 2017 with the aim to assess the prevalence of PoSH and to identify patient and disease related factors associated with postoperative hypocalcemia.
Results: 171 (30.97%) patients [153 women (89.5%), median(IQR) age 49(22) years] developed PoSH (88.37% transient). The median(IQR) duration of postoperative hypocalcemia was 60 (67.5) days. Compared to 39 age and sex matched patients without PoSH, patients with PoSH presented the same prevalence of thyroid pathology that recommended thyroidectomy: multinodular goiter 55.6% vs 46.2%, Graves disease 12.9% vs 17.9%, thyroid carcinoma 31.6% vs 35.9% (P=0.52). Preoperative biological parameters (calcemia, PTH, 25-hydroxyvitamine D, phosphatemia, alkaline phosphatase, creatinine, TSH, FT4, TPOAb) were the same in both groups; yet, median(IQR) magnesemia was significantly higher in PoSH group [2.04(0.17) vs. 1.89(0.28) mg/dl, P=0.005]. Preoperative ultrasound characteristics, surgical protocols and pathological data were similar in the two groups. The patients with thyroid cancer that developed PoSH compared to controls had a longer median duration of thyroid surgery [135(60) vs. 110(43) min, P=0.02]. In patients with PoSH, median postoperative calcemia was significantly higher in patients with reported difficult surgery [8.2(0.2) vs. 7.9(0.6) mg/dl, P=0.043] and the mean calcemia decrease was higher in patients with cervical neck dissection and lymphadenectomy (1.94±0.59 vs. 1.68±0.56 mg/dl, P=0.033).
Conclusions: Our data show a high prevalence of PoSH that is likely to increase given the rising number of thyroid surgeries being performed. Further research is needed in order to better define this condition, to establish appropriate treatment and preventive measures.