Endocrine Abstracts

Objective: Postoperative hypocalcemia is one of the major concerns following total thyroidectomy as well as the most frequent cause of prolonged hospital stay. The first purpose of this study was to evaluate the relationship between body composition parameters and symptomatic hypocalcemia following total thyroidectomy. In addition, the effects of disease- and patient-related factors on hypocalcemia were investigated.

Methods: In this cohort study, a total of 144 patients were included prospectively between March 2014 and September 2017. Demographics, preoperative biochemical parameters including serum calcium, albumin, parathyroid hormone (PTH), vitamin D, and thyroid function tests, ultrasonographic features of the dominant nodule, placement of the thyroid gland, and histopathological findings were recorded. The body composition measurements including weight, height, body mass index (BMI), total body water, free fat mass, fat mass, body fat range, muscle mass, bone mass, degree of obesity, and visceral fat rating were obtained using a bioelectrical impedance analyzer. Patients who underwent total thyroidectomy were divided into two groups according to the presence or absence of hypocalcemic symptoms. Subsequently, the relationship between body composition parameters and symptomatic hypocalcemia were evaluated.

Results: Postoperative symptomatic hypocalcemia occurred in 28 patients (19.4%). Permanent hypocalcemia was not encountered in any patient in the 12-month follow-up period. Patients with hypocalcemic symptoms were more likely to have a dominant nodule larger than 40 mm (39.3% vs. 17.2%, P=.011), retrosternal goiter (25.0% vs. 7.8%, P=.017), and parathyroid autotransplantation (28.6% vs. 3.4%, P<.001) compared with those without symptoms. However, no differences were observed for body composition parameters between symptomatic and non-symptomatic patients. In addition to these findings, when evaluated separately, patients with a BMI ≥25 kg/m² had a similar operative time (117.8 min vs. 117.4 min; P=0.693) and length of hospital stay (32.7 h vs. 31.0 h; P=0.461) to patients with a BMI <25 kg/m². On multivariate analysis, lower preoperative PTH levels (OR 1.05, 95% CI 0.93−1.00, P=.028), presence of retrosternal goiter (OR 5.26, 95% CI 1.45−19.16, P=.012), and parathyroid autotransplantation (OR 16.85, 95% CI 3.68−77.11, P < .001) were the independent predictors of symptomatic hypocalcemia.

Conclusion: This study demonstrates that patients with lower preoperative PTH levels, retrosternal goiter, and parathyroid autotransplantation are at increased risk of developing postoperative hypocalcemia. Body composition parameters have no effect on the incidence of symptomatic hypocalcemia after total thyroidectomy.