Clinical problems in thyroid surgery

Background: Thyroid surgery is the most common endocrine surgical operation and is considered by many to be at the zenith of endocrine surgery. A good hemostasis is mandatory during a thyroid operation and many new devices have been available during the last two decades. Total thyroidectomy, (TT) is now by many surgeons considered the method of choice when treating Graves´ disease (GD) and multinodular goitres (MNG) surgically. Hypocalcaemia is the most common adverse event after thyroid surgery and the reported frequency ranges from 4-55 %. It is difficult to identify and predict patients at risk for developing postoperative hypocalcaemia. Previously described risk factors for transient hypocalcaemia are extent of surgery, lymph node dissection, GD, bone hunger and the number of parathyroid glands identified peroperatively and parathyroid autotransplantation. Aims: To compare two different operation techniques for patients with GD undergoing TT and the risk of hypocalcaemia after TT for patients with MNG and GD, respectively. To identify risk factors for postoperative hypocalcaemia after TT in patients with GD and to predict risk factors for permanent hypocalcaemia after TT. Methods: In Paper I we compared in a prospective randomised controlled trial, a conventional operation technique vs. ultracision (Harmonic Scalpel(HS)) when performing TT. In Paper II, we compared the risk for hypocalcaemia between patients with GD and MNG undergoing TT. In Paper III, data were extracted from the Scandinavian Quality Register for Thyroid and Parathyroid Surgery (SQRTP) and patients with GD undergoing TT during year 2004 – 2008 in 23 surgical departments in Sweden were studied. In Paper IV, risk factors of permanent hypoparathyroidism after TT from a prospective database at the same surgical department was analysed. Results: 27 patients were randomised to the HS group and 24 patients to the conventional group (knot tying). Operation time was significantly shorter in the HS group (I). Patients with GD (n=129) were younger than patients with MNG (n=81). Symptoms of hypocalcaemia were more common in patients with GD but there were no other differences between the two groups (II). Risk factors for i.v. calcium after TT in patients with Graves´ disease were low hospital volume, operative time, university hospital and reoperation due to postoperative hematoma. Risk factors for treatment with vitamin D at discharge increased with operative time, weight of the specimen, parathyroid autotransplantation and reoperation. Risk factors for treatment with vitamin D at first follow up at 6 weeks were weight of the specimen, preoperative treatment with beta blockers. At 6 months follow up, risk factors for treatment with vitamin D were weight of the specimen and reoperation (III). There were 519 patients, median follow up (range) was 2.7 years (1.2 – 10.3). The rate of permanent hypoparathyroidism was 1.9 %. Parathyroid autotransplantation was performed in 90/519, 17.3 % and none of these developed permanent hypoparathyroidism, as did no patient with normal PTH level on day one postoperatively. Conclusion: Patients with GD undergoing TT performed with Harmonic Scalpel® had a significantly shorter operation time, without an increased risk for complications. Patients with GD were younger and experienced more often symptoms of hypocalcaemia after TT compared to patients with goitres, but there were no biochemical differences. Risk factors for medically treated hypocalcaemia after TT in patients with Graves´ disease are multifactorial and vary over follow-up time. A low PTH level early after TT is associated with a high risk of permanent hypoparathyroidism. Normal levels of PTH postoperatively exclude long term hypoparathyroidism. Parathyroid autotransplantation seems to be warranted as a way of minimizing the risk of permanent hypoparathyroidism