Incidence Of Postoperative Hypoparathyroidism Research Articles

Incidence of Post-Thyroidectomy Hypoparathyroidism and Associated Preoperative and Intraoperative Risk Factors.

Thyroidectomy technique and extent are related to parathyroid injury and hypoparathyroidism. Total thyroidectomy is one of the most commonly performed endocrine surgeries, and the majority of patients recover completely without any complications. However, persistent hypoparathyroidism is the most prevalent long-term consequence following total thyroidectomy. While it is seldom deadly, it can cause severe morbidity for the patient and raise healthcare expenses. This retrospective cohort study was conducted at King Abdulaziz Medical City, Jeddah, Saudi Arabia. We included all confirmed thyroid cancer cases that underwent thyroidectomy with or without neck dissectionbetween July 2016 and August 2022. The data was collected from a chart review of the electronic medical record system (BEST-care), and a data collection sheet was utilized. SPSS version 26 was used to analyze the data. A total of 192 patients undergoing thyroid surgery were enrolled. One hundred forty-three (74.5%) were females and the mean age of participants was 45.29 ± 16.88 years. Most patients, 170 (88.5%), had a papillary histological type, and total thyroidectomy was performed in 150 (78.1%). A significant association was found between the type of surgery and postoperative hypoparathyroidism (p=<0.05*). In addition, hypocalcemia was seen in 147 (76.6%) of the patients. Postoperative hypoparathyroidism was significantly higher among patients who had asymptomatic postoperative hypocalcemia and those who received IV calcium gluconate (p=<0.05*). Moreover, postoperative hypocalcemia, hypomagnesemia, and hyperphosphatemia were significantly associated with postoperative hypoparathyroidism (p=<0.05*). The incidence of postoperative hypoparathyroidism is significantly higher among patients who underwent total thyroidectomy and had a normal level of preoperative parathyroid hormone (PTH) and magnesium (Mg) levels. Identifying these factors is a crucial step to minimize the occurrence of such complications.

Primary hyperparathyroidism in patients with multiple endocrine neoplasia type 1: Impact of genotype and surgical approach on long-term postoperative outcomes

BackgroundProtein-truncating germline pathogenic variants in the N- and C-terminal exons (2, 9, and 10) of the MEN1 gene may be associated with aggressive pancreatic neuroendocrine tumors. However, the impact of these variants on parathyroid disease is poorly understood. We sought to investigate the effects of genotype and surgical approach on clinical phenotype and postoperative outcomes in patients with multiple endocrine neoplasia type 1 (MEN1)-related primary hyperparathyroidism. MethodsWe identified patients with MEN1 evaluated at our institution from 1985 to 2020 and stratified them by genotype, (truncating variants in exons 2, 9, or 10, or other variants), and index surgical approach, (less-than-subtotal parathyroidectomy [<SPTX], SPTX, or total parathyroidectomy). We analyzed baseline characteristics, persistent/recurrent disease rates, and incidence of postoperative hypoparathyroidism. ResultsOf the 209 patients we identified, primary hyperparathyroidism was diagnosed in 194 (93%) and at a younger median age in those with truncating exon 2, 9, or 10 variants compared with other variants (27 years vs 31 years; P = .006). Median disease-free survival was significantly worse in patients who underwent <SPTX (60 months) than those who underwent <SPTX (152 months; P = .0005) or total parathyroidectomy (210 months; P = .04). Patients with truncating exon 2, 9, or 10 variants who underwent <SPTX had significantly shorter median disease-free survival than those with other variants (30 vs 84 months; P = .007). Prolonged hypoparathyroidism rates after final surgery were highest after total parathyroidectomy (40%), followed by <SPTX (9%) and SPTX (7%). ConclusionThe MEN1 genotype may affect the age of onset of primary hyperparathyroidism and the time to recurrence after surgery. <SPTX at index operation should be performed with caution, especially in patients with truncating MEN1 variants in exons 2, 9, or 10, as the higher risk of recurrence is not offset by a decreased incidence of permanent hypoparathyroidism compared to upfront SPTX.

A Personalized 3D-Printed Model for Preoperative Evaluation in Thyroid Surgery.

The anatomic structure of the surgical area of thyroid cancer is complex. It is very important to comprehensively and carefully evaluate the tumor location and its relation with the capsule, trachea, esophagus, nerves, and blood vessels before operation. This paper introduces an innovative 3D-printed model establishment method based on computerized tomography (CT) DICOM images. We established a personalized 3D-printed model of the cervical thyroid surgery field for each patient who needed thyroid surgery to help clinicians evaluate the key points and difficulties of the surgery and select the operation methods of key parts as a basis. The results showed that this model is conducive to preoperative discussion and the formulation of operation strategies. In particular, as a result of the clear display of the recurrent laryngeal nerve and parathyroid gland locations in the thyroid operation field, injury to them can be avoided during surgery, the difficulty of thyroid surgery reduced, and the incidence of postoperative hypoparathyroidism and complications related to recurrent laryngeal nerve injury reduced too. Moreover, this 3D-printed model is intuitive and aids communication for the signing of informed consent by patients before surgery.

Impact of Enhanced Parathyroid Autofluorescence on post-operative Hypoparathyroidism in thyroid cancer surgery

Background: Hypoparathyroidism (HypoPT) is one of the most common complications after thyroid surgery. In a recent meta-analysis by Edafe et al, the incidence of temporary and permanent hypoPT following thyroidectomy ranged from 19% to 38% and 0% to 3%, respectively. These rates are higher when surgery is offered for thyroid cancer when additional nodal dissection is performed. The visual identification of parathyroid gland is difficult because of its small size and appearance that is commonly confused with lymph node, fat or sometimes even thyroid tissue and to add to this is variability in its location. In 2011, Paras et al demonstrated parathyroid glands possess intrinsic autofluorescence (AF). By exploiting the inherent autofluorescence nature of parathyroid by use of Near infra-red imaging, the identification rates during surgery can be improved and by corollary, the incidence of hypocalcemia can be reduced post operatively. This study attempts to assess the Impact of Parathyroid Autofluorescence (both enhanced and non-enhanced) on parathyroid identification and in the incidence of post-operative hypoparathyroidism after thyroid cancer surgery.

Clinical application of parathyroid autotransplantation in endoscopic radical resection of thyroid carcinoma

PurposeThis study aimed to examine the effect of selective inferior parathyroid gland autotransplantation on central lymph node dissection(CLND) and incidence of postoperative hypoparathyroidism in patients undergoing endoscopic radical resection of thyroid carcinoma.MethodsThe data of 310 patients undergoing endoscopic radical resection of thyroid carcinoma will be retrospectively analyzed. The patients will be divided into the experimental group and the control group according to whether they combined with parathyroid autotransplantation. Statistics of the incidence rate of postoperative hypoparathyroidism, the concentration of PTH and Calcium in the systemic circulation at different time points in the two groups, the concentration of PTH in the cubital fossa vein in the transplantation region in the experimental group, and the number of central lymph nodes and positive lymph nodes dissection will be carried out.ResultsThe incidence rate of temporary and permanent hypoparathyroidism in the experimental group was 33.75% and 0.625%, respectively, and in the control group was 22% and 5%, respectively; its difference was statistically significant (X2 = 10.255, P=0.006). Parathyroid autotransplantation increased incidence of transient hypoparathyroidism (OR, 1.806; Cl, 1.088-2.998; P=0.022), and lower incidence of permanent hypoparathyroidism (OR, 0.112; Cl, 0.014-0.904; P=0.040). The diameters of thyroid cancer nodules was not associated with the occurrence of transient hypoparathyroidism (OR, 0.769; Cl, 0.467-1.265; P=0.301) or permanent hypoparathyroidism (OR, 1.434; Cl, 0.316-6.515; P=0.641). Comparison of systemic circulation PTH, between the two groups showed that the PTH of patients in the experimental group was higher than that in the control group from 1 week to 12 months after the operation, and the difference was statistically significant (P<0.05). In the experimental group, from 1 week to 12 months after surgery, PTH concentrations was significantly higher in the cubital fossa of the transplantation side than in the contralateral side, and the differences were statistically significant (P<0.05). The mean number of central lymph node dissected per patient was significantly higher in the experimental group (7.94 ± 3.03 vs. 6.99 ± 2.86; P <0.05); The mean number of positive nodes per patient was significantly higher in the experimental group (3.16 ± 1.86 vs. 2.53 ± 1.59; P <0.05).ConclusionsIn endoscopic radical resection of thyroid carcinoma, parathyroid autotransplantation is more beneficial to postoperative parathyroid glands function recovery, effectively preventing postoperative permanent hypoparathyroidism and realizing more thorough CLND.

Autofluorescence of parathyroid glands during endocrine surgery with minimally invasive technique.

Accidental injury to the parathyroid glands (PTGs) is common during thyroid and parathyroid surgery. To overcome the limitation of naked eye in identifying the PTGs, intraoperative autofluorescence imaging has been embraced by an increasing number of surgeons. The aim of our study was to describe the technique and assess its utility in clinical practice. Near-infrared (NIR) autofluorescence imaging was carried out during open parathyroid and thyroid surgery in 25 patients (NIR group), while other 26 patients underwent traditional PTG detection based on naked eye alone (NO-NIR group). Primary variables assessed for correlation between traditional approach and autofluorescence were number of PTGs identified and incidence of postoperative hypoparathyroidism (hypoPT). 81.9% of PTGs were detected by means of fluorescence imaging and 74.5% with visual inspection alone, with an average of 2.72 PTGs visualized per patient using NIR imaging versus approximately 2.4 per patient using naked eye (p = 0.38). Considering only the more complex total thyroidectomies (TTs), the difference was almost statistically significant (p = 0.06). Although not statistically significant, the observed postoperative hypoPT rate was lower in the NIR group. Despite the limitations and technical aspects still to be investigated, fluorescence seems to reduce this complication rate by improving the intraoperative detection of the PTGs.

Indocyanine green fluorescence for parathyroid gland identification and function prediction: Systematic review and meta-analysis.

To evaluate the diagnostic accuracies of indocyanine green (ICG) fluorescence for identifying parathyroid glands during surgery and predicting the postoperative function. From six databases, 21 studies were finally included in the study. True-positive, true-negative, false-positive, and false-negative data were extracted for the analysis. The quality of each study was analyzed using the QUADAS-2 tool. The sensitivity of ICG-based parathyroid gland identification was 0.9380 (95% CI [0.9003, 0.9621]). The diagnostic odds ratio for ICG-based prediction of parathyroid gland function was 54.5652 [13.2059, 225.4570]. The area under the summary receiver operating characteristic curve was 0.909. Fluorescence intensity-based prediction presented higher diagnostic accuracy than that of score-based prediction. The incidence of postoperative hypoparathyroidism was higher in the group with a zero ICG score compared to the high scored group. Identification of parathyroid gland and prediction of postoperative function using ICG are valuable to patients undergoing thyroidectomy or parathyroidectomy.

Tissue dissection with saline injection: application in thyroid surgery.

Postoperative hypoparathyroidism is a thyroidectomy complication. The effect of this complication cannot be accurately quantified. The incidence of hypoparathyroidism after total thyroidectomy has high variability in the literature, between 7 and 37%. Data from 78 patients who underwent total thyroidectomy with Tissue Dissection with Solution Injection (TDSI group) from December 2018 to August 2019 were retrospectively reviewed. These patients were compared with 78 patients to whom the technique was not applied (non-TDSI group), and they were treated from January 2018 to September 2018. All thyroidectomies were performed by the same surgeon. The mean duration of a thyroidectomy was 1 hour. The reduction of the incidence of postoperative hypoparathyroidism in the group of patients was applied in respect of the technique of tissue dissection with saline injection. TDSI technique paves the way for further application to other tissues and surgeries.

Assessment of Inter-Institutional Post-Operative Hypoparathyroidism Status Using a Common Data Model.

Post-thyroidectomy hypoparathyroidism may result in various transient or permanent symptoms, ranging from tingling sensation to severe breathing difficulties. Its incidence varies among surgeons and institutions, making it difficult to determine its actual incidence and associated factors. This study attempted to estimate the incidence of post-operative hypoparathyroidism in patients at two tertiary institutions that share a common data model, the Observational Health Data Sciences and Informatics. This study used the Common Data Model to extract explicitly specified encoding and relationships among concepts using standardized vocabularies. The EDI-codes of various thyroid disorders and thyroid operations were extracted from two separate tertiary hospitals between January 2013 and December 2018. Patients were grouped into no evidence of/transient/permanent hypoparathyroidism groups to analyze the likelihood of hypoparathyroidism occurrence related to operation types and diagnosis. Of the 4848 eligible patients at the two institutions who underwent thyroidectomy, 1370 (28.26%) experienced transient hypoparathyroidism and 251 (5.18%) experienced persistent hypoparathyroidism. Univariate logistic regression analysis predicted that, relative to total bilateral thyroidectomy, radical tumor resection was associated with a 48% greater likelihood of transient hypoparathyroidism and a 102% greater likelihood of persistent hypoparathyroidism. Moreover, multivariate logistic analysis found that radical tumor resection was associated with a 50% greater likelihood of transient hypoparathyroidism and a 97% greater likelihood of persistent hypoparathyroidism than total bilateral thyroidectomy. These findings, by integrating and analyzing two databases, suggest that this analysis could be expanded to include other large databases that share the same Observational Health Data Sciences and Informatics protocol.

Near-Infrared Autofluorescence Imaging May Reduce Temporary Hypoparathyroidism in Patients Undergoing Total Thyroidectomy and Central Neck Dissection.

Background: Near-infrared autofluorescence (NIRAF) imaging is known to reduce the incidence of post-thyroidectomy hypocalcemia. However, there are no studies on how much NIRAF imaging affects the serum parathyroid hormone (PTH) level after surgery. We investigated the changes of the serum PTH level and ionized calcium (iCa.) in patients undergoing total thyroidectomy with central neck dissection (CND). Materials and Methods: This retrospective study with historical control enrolled 542 patients who underwent total thyroidectomy with CND. Patients were divided into two groups: the NIRAF group (261 patients) and the control group (281 patients). PTH and iCa. levels were measured at the hospital stay, 1, 3, and 6 months after surgery. In addition, the number of identified parathyroid glands (PGs), autotransplanted PGs, and the inadvertent resection rate of PGs was evaluated. Results: The incidence of postoperative hypoparathyroidism (PTH <15 pg/mL) was significantly lower in the NIRAF group during the hospitalization (88 patients: 33.7% vs. 131 patients: 46.6%; p = 0.002) and at 1 month postoperatively (23 patients: 8.8% vs. 53 patients: 18.9%; p = 0.001). There was no difference in the permanent hypoparathyroidism rate (6 months after surgery) between the NIRAF group and the control group (4.2% vs. 4.6%; p = 0.816). There was no difference in the incidence of hypocalcemia (iCa. <1.09 mmol/L) (during hospitalization: 6.5% vs. 10.0%; 1 month: 2.3% vs. 2.5%; 3 months: 0.8% vs. 0.7%; 6 months after surgery: 1.1% vs. 1.1%) between the two groups. The number of inadvertently resected PGs was significantly lower in the NIRAF group (18:6.9% vs. 36:12.8%; p = 0.021). Conclusions: These results suggest that NIRAF imaging may reduce temporary hypoparathyroidism and the risk of inadvertent resection of PGs in patients undergoing total thyroidectomy with CND.

Development of a Rapid Intraoperative Point-of-Care Method Using Tissue Suspension to Differentiate Parathyroid Tissue: A Possible Substitute for Frozen Sections.

We reported that aspartate aminotransferase (AST)/lactate dehydrogenase (LDH) ratio of a tissue suspension can precisely differentiate normal and hyperfunctioning parathyroid tissue (PT) from other tissues. However, in these studies, LDH and AST were measured using the standard method for blood samples, with a turnaround time of approximately 1h, hampering clinical application. Here, we developed a rapid and robust method to differentiate PT instead of using frozen sections. Excised specimens from 28 patients (n = 69) who underwent thyroid or parathyroid surgery between October 2019 and April 2020 were analyzed. AST and LDH were measured in suspensions of PT or other tissues, using both the standard method in the in-facility laboratory and a point-of-care testing device (NX500, Fujifilm, Japan). A good correlation was found between the standard method and NX500 for AST and LDH levels >10IU/L. In the analyses using 52 specimens with ≥ 10IU/L of both AST and LDH measured using the NX500, PT was distinguished with 100% sensitivity and specificity using an optimal cutoff AST/LDH ratio of 0.48. The turnaround time was estimated to be less than 10min. This method could be a cost- and labor-effective alternative to frozen sections to reduce the incidence of postoperative hypoparathyroidism and improve the outcome of primary hyperparathyroidism in low-resource areas.

Total Thyroidectomy with Central Node Dissection is a Valuable Option in Papillary Thyroid Cancer Treatment.

SUMMARYIntroductionPapillary thyroid cancer is one of the cancers with favorable prognosis, although the long-term recurrence rate in the paratracheal region is reported to be as high as 30%. The use of 131I is considered to be a reliable treatment option for lymph node metastases in the paratracheal region. According to the majority of internationally accepted guidelines, it is not recommended to perform central node dissection (CND) routinely. Total thyroidectomy (TT) remains an adequate treatment for these patients. According to many studies, CND is associated with higher rates of hypoparathyroidism. However, CND improves staging.MethodsWe performed a retrospective study. We included 248 patients treated for papillary thyroid cancer during a 20-year period. Data were collected on patient (age, sex) and tumor (size, focality) characteristics, presence of metastases in the central neck compartment, incidence of postoperative hypoparathyroidism, and locoregional failure. We divided patients into two groups based on pathological analysis: those without positive lymph nodes (N0) and those with positive paratracheal lymph nodes (N1). We compared patient and tumor characteristics and risk of recurrence between the two groups. Results: There were 39.5% patients with central neck metastases in our series. In the central neck dissection specimen, 5.5 nodes were found on average. Hypoparathyroidism was found in 23.4% of patients and remained permanent in 3.2% of patients. Female and older patients had a lower chance of central compartment metastases, as did patients with smaller and unifocal tumors. Recurrence risk was doubled for the N1 group. All tested differences between the groups reached statistical significance.Discussion and conclusionIn our hands, CND was a safe and effective surgical procedure. It improved staging and postsurgical management. Efforts should be made to improve the preoperative work-up in order to more accurately identify high-risk patients.

The effectiveness of parathyroid gland autotransplantation in preserving parathyroid function during thyroid surgery for thyroid neoplasms: A meta-analysis

ObjectiveWe conducted this meta-analysis to assess the effectiveness of parathyroid gland autotransplantation in preserving parathyroid function during thyroid surgery for thyroid neoplasms.MethodsWe conducted a search by using PubMed, Embase, and the Cochrane Library electronic databases for studies that were published up to January 2019. The reference lists of the retrieved articles were also reviewed. Two authors independently assessed the methodological quality and extracted the data. A random-effects model was used to calculate the overall combined risk estimates. Publication bias was evaluated with a funnel plot using Egger’s and Begg’s tests.ResultsA total of 25 independent studies involving 10,531 participants were included in the meta-analysis. Compared with patients who did not undergo parathyroid gland autotransplantation, the overall pooled relative risks for patients who underwent parathyroid gland autotransplantation were 1.75 (95% CI: 1.51–2.02, p<0.001) for postoperative hypoparathyroidism, 1.72 (95% CI: 1.45–2.05, p<0.001) for protracted hypoparathyroidism, 1.06 (95% CI: 0.44–2.58, p = 0.894) and 0.71 (95% CI: 0.22–2.29, p = 0.561) for biochemical hypoparathyroidism and biochemical hypocalcemia at 6 months postoperatively, respectively, and 1.89 (95% CI: 1.33–2.69, p<0.001) and 0.22 (95% CI: 0.09–0.52, p = 0.001) for biochemical hypoparathyroidism and biochemical hypocalcemia at 12 months postoperatively, respectively. The pooled relative risks for patients who underwent one parathyroid gland autotransplantation and patients who underwent two or more parathyroid gland autotransplantations were 1.71 (95% CI: 1.25–2.35, p = 0.001) and 2.22 (95% CI: 1.43–3.45, p<0.001) for postoperative hypoparathyroidism, 1.09 (95% CI: 0.59–2.01, p = 0.781) and 0.55 (95% CI: 0.16–1.87, p = 0.341) for hypoparathyroidism at 6 months postoperatively compared with those of patients who did not undergo parathyroid gland autotransplantation.ConclusionsParathyroid gland autotransplantation is significantly associated with increased risk of postoperative and protracted hypoparathyroidism, and the number of autoplastic parathyroid glands is positively correlated with the incidence of postoperative hypoparathyroidism.

Risk factors for hypoparathyroidism after thyroidectomy

To investigate the risk factors for hypoparathyroidism after thyroidectomy. Methods: Clinical data of 492 patients, who underwent thyroidectomy from April 2015 to December 2016 from Xiangya Hospital of Central South University, were studied retrospectively. Chi-square test and multivariable logistic regression were performed to find the risk factors for postoperative hypoparathyroidism. Results: The incidence of postoperative hypoparathyroidism was 43.5%, and the incidence of temporary and permanent hypoparathyroidism was 43.1% and 0.4%, respectively. Univariate analysis showed that tumor pathology, thyroidectomy types, the extent of lymph node dissection, application of carbon nanoparticles, and merged Hashimoto's thyroiditis were risk factors for postoperative hypoparathyroidism (all P<0.01). Logistic regression analysis showed that: thyroidectomy types (OR=0.149, 95% CI 0.078 to 0.28), the extent lymph node dissection (OR=0.779, 95% CI 0.617 to 0.983) and application of carbon nanoparticles (OR=1.729, 95% CI 1.067 to 2.801) were independent risk factors for postoperative hypoparathyroidism (all P<0.05). Conclusion: Hypoparathyroidism is a common complication after thyroidectomy. The incidence of postoperative hypoparathyroidism is significantly increased in patients underwent total thyroidectomy and cervical lymph node dissection. Application of carbon nanoparticles intraoperatively can reduce the incidence of postoperative hypoparathyroidism.

In situ preservation of parathyroid glands during thyroid surgery for prevention of hypoparathyroidism

Background: Hypoparathyroidism (HPT) is one of the most frequent and severe complications of thyroid surgery. It is caused by intraoperative damage, devascularization or accidental removal of the parathyroid glands (PTG). The incidence of postoperative HPT is directly proportional to surgery extent and surgeon’s experience. However, it can be significantly reduced by excellent surgical technique. The authors present original technique of in situ preservation of PTGs during thyroid surgery and 40-years-experience results in postoperative HPT.

Post-operative Transient Hypoparathyroidism: Incidence and Risk Factors

Background : There is limited data on the incidence and risk factors for developing postoperative hypoparathyroidism (POHP) in the South African setting. Objectives : This study aims to calculate the incidence of postoperative hypoparathyroidism in a South African tertiary setting, and to compare local risk factors for POHP to international published data. Methods : All patients who underwent a total or completion thyroidectomy at an academic referral center from January 2010 to December 2015 were included. Data reviewed included post-operative parathyroid hormone (iPTH) level, demographics, type of operation and lymphadenectomy, size of thyroid glands resected, final histology, extra capsular extension of carcinomas, number of lymph nodes resected, and the number of parathyroid excised. Results : Postoperatively, 29% of patients were diagnosed with hypoparathyroidism. Overall, there was no association between POHP and age or gender. In patients with benign histology, size was significantly associated with higher rates of POHP. In patients with thyroid carcinoma, lymphadenectomy and the number of lymph nodes resected were associated with higher rates of POHP. Conclusion : The incidence of immediate postoperative hypoparathyroidism is within international standards. Standardized postoperative follow up is necessary, and strategies to improve POPH such as auto transplantation in locally identified high-risk subgroups should be considered. Key words : Postthyroidectomy, Hypocalcaemia, Hypoparathyroidism

Natural History, Treatment, and Course of Papillary Thyroid Carcinoma*

We have analyzed the course of papillary thyroid carcinoma in 269 patients managed at the University of Chicago, with an average follow-up period of 12 yr from the time of diagnosis. Patients were categorized by clinical class; I, with intrathyroidal disease; II, with cervical nodal metastases; III, with extrathyroidal invasion; and IV, with distant metastases. Half of the patients had a history of thyroid enlargement known, on the average, for over 3 yr. In 15% of patients given thyroid hormone, the mass decreased in size. The peak incidence of cancer was when subjects were between 20-40 yr of age. Tumors averaged 2.4 cm in size; 21.6% had tumor capsule invasion, and 46% of patients had multifocal tumors. Sixty-six percent of the patients had near-total or total thyroidectomy. The overall incidence of postoperative hypoparathyroidism was 8.4%, but the incidence was zero in 83 near-total or total thyroidectomies carried out by 1 surgeon. Twenty-five percent of the patients had continuing or recurrent disease, and 8.2% died from cancer. Deaths occurred largely in patients with class III or IV disease. Cervical lymph nodes were associated with increased recurrences, but not increased deaths. Extrathyroidal invasion carried an increased risk of 5.8-fold for death, and distant metastases increased this risk 47-fold. Age over 45 yr at diagnosis increased the risk of death 32-fold. Tumor size over 3 cm increased the risk of death 5.8-fold. Surgical treatment combining lobectomy plus at least contralateral subtotal thyroidectomy was associated, by Cox proportional hazard analysis, with decreased risk of death in patients with tumors larger than 1 cm and decreased risk of recurrence among all patients, including patients in classes I and II, compared to patients who underwent unilateral thyroid surgery or bilateral subtotal resections. By chi 2 analysis, 131I ablation of residual thyroid tissue after operation was associated with decreased risk of recurrence in tumors larger than 1 cm and decreased risk of death in patients in classes I and II with tumors more than 1 cm in size. The data strongly support the use of more extensive initial surgery in class I and II patients with tumors more than 1 cm in size as well as postoperative radioactive 131I ablation of thyroid remnant tissue.