Long term thyroid function after subtotal thyroidectomy for Graves' disease

Recurrence of Graves' disease in thyroglossal duct remnants: relapse after total thyroidectomy

BACKGROUND

Ectopic thyroid tissue can be found anywhere between the foramen cecum and the normal position of the thyroid gland, most commonly located in the anterior cervical area, the region of the thyroglossal duct. Although thyroid cancer has been described frequently in thyroglossal duct remnants, thyroid dysfunction related to this tissue is rare. We report a patient with recurrent Graves' disease arising in a thyroglossal duct remnant.

SUMMARY

A 40-year-old woman with a history of total thyroidectomy for Graves' disease, presented with a slowly enlarging midline neck mass in association with clinical signs of hyperthyroidism. Serum-free triiodothyronine (6.6 pg/mL) and serum-free thyroxine (2.2 ng/dL) were elevated (normal range, 2.3-4.2 pg/mL and 0.9-1.8 ng/dL, respectively), and thyroid-stimulating hormone was suppressed (<0.01 mIU/mL; normal range, 0.35-5.50 mIU/mL). Neck ultrasonography showed a solid mass, localized at the infrahyoid area; radionuclide scanning confirmed an increased uptake at the same level. A 4 cm solid mass was removed by the Sistrunk technique. Microscopic examination revealed marked follicular hyperplasia, with tall cells, small follicles, scant, and scalloped colloid, in association with patchy lymphocytic infiltrate consistent with Graves' disease.

CONCLUSIONS

There appears to be no reason why thyroid cells within thyroglossal duct remnants should not be influenced by the thyroid-stimulating immunoglobulins of Graves' disease. Thyrotoxicosis resulting from this must be very rare, however, as were unable to find reports of patients with thyrotoxicosis due to Graves' disease in thyroglossal duct remnants. Although some thyroid tissue can be found within the thyroglossal duct in 1.6% to 40% of normal adults, the risk of thyroid dysfunction from this is far too low to justify new therapeutic approaches.

Surgical management of Graves' disease -10-year prospective trial at a single institution

The extent of thyroidectomy in Graves' disease is still controversial. In our institution, long term euthyroidism without thyroxine replacement therapy has been aimed and, thus, subtotal thyroidectomy has been employed. We prospectively studied whether the surgical outcome was improved by a strategy of leaving smaller thyroid remnants. Between 1989 and 1998, 1897 patients with Graves' disease were treated by subtotal thyroidectomy and their thyroid function could be determined 2 to 3 years after thyroidectomy. The 10-year period was divided into 3 parts, '89-'91 (Period 1, n = 690), '92-'94 (Period 2, n = 587) and '95-'98 (Period 3, n = 620). Different maximum thyroid remnant sizes were prospectively established for each period: up to 7 g left in Period 1, up to 6 g in Period 2 and up to 5 g in Period 3. Thyroid function 2 to 3 years after thyroidectomy and the occurrence of surgical complications were compared among the three groups. The relapse rate for Period 1, Period 2, and Period 3 was 14.1%, 12.6%, and 10.9%, respectively, and the rate of euthyroidism decreased and rate of hypothyroidism increased from period to period. Surgical complications increased in Periods 2 and 3. For preventing relapse, the strategy of reducing the thyroid remnant is effective. Subtotal thyroidectomy leaving 3-4 g remnant tissue is a suitable surgical option for Graves' disease.

[Prognostic factors of thyroid function following surgical therapy in Graves-Basedow's disease]

BACKGROUND

The goals of this work are to describe late thyroid function and to determine predictive factors of permanent hypothyroidism following surgery in Graves-Basedow's disease.

PATIENTS AND METHOD

From 1979 to 1999, 107 patients with hyperthyroidism due to Graves-Basedow's disease underwent subtotal thyroidectomy. We performed life-table analysis and calculated the cumulative incidence of hypothyroidism by means of the Kaplan-Meier's method. Survival (euthyroidism)within patients groups was compared using the Mantel-Cox method. Variables influencing long-term thyroid function were determined by estimating the Odds ratio with a logistic regression model.

RESULTS

The probability of euthyroidism among all 107 patients at 240 months was 51.4%.Age, gender, duration of both hyperthyroidism and antithyroid therapy and weight of resected thyroid tissue did not influence the eventual outcome. The weight of thyroid remnant was 5.4 (1.5)g and the conditional logistic regression analysis showed that weight of thyroid remnant was the only variable influencing long-term thyroid function. Hyperthyroidism relapsed in 5 patients.

CONCLUSIONS

In our experience,surgery represents a definitive alternative treatment with a risk of hypothyroidism within the first 2 years of 43.9%. The weight of thyroid remnant is the only variable influencing long-term thyroid function.

The efficacy of thyroidectomy for Graves' disease: A meta-analysis

BACKGROUND

Surgery for Graves' disease was largely replaced in the mid-1900s by radioiodine and antithyroid drugs, due to the belief that they were more safe and effective. Since then, thyroid surgery has improved with preoperative drug therapy and modern operative techniques. Recent clinical studies of thyroidectomy for Graves' disease may not reflect outcomes accurately because of small sample size, especially when estimating ideal thyroid remnant size. The purpose of this study was to combine modern clinical trials and use meta-analysis to determine the overall efficacy of both total (TT) and subtotal thyroidectomy (ST) for Graves' disease, compare thyroid function and complications rates of TT and ST, and determine ideal thyroid remnant size.

METHODS

Meta-analysis was performed on published studies in which patients underwent either TT or ST for Graves' disease. Meta-analysis was performed by weighted least-squares linear regression. P < 0.05 was considered significant.

RESULTS

There were 35 studies comprising 7241 patients. Mean follow-up was 5.6 years. Overall, persistent or recurrent hyperthyroidism occurred in 7.2% of patients. TT was performed on 538 patients and hypothyroidism occurred in all cases. ST was performed in 6703 patients, 59.7% of whom achieved euthyroidism, 25. 6% became hypothyroid, and 7.9% had either persistent or recurrent hyperthyroidism. Permanent recurrent laryngeal nerve injury occurred in 0.9% of TT patients and 0.7% of ST patients (P = NS). Permanent hypoparathyroidism occurred in 1.6% of TT patients and 1.0% of ST patients (P = NS). There was an 8.9% decrease in hypothyroidism and 6.9% increase in euthyroidism for each gram of thyroid remnant (P < 0.0001 each).

CONCLUSIONS

Overall, thyroidectomy successfully treated hyperthyroidism in 92% of patients with Graves' disease. There were no cases of hyperthyroidism following TT. ST achieved a euthyroid state in almost 60% of patients with an 8% rate of persistent or recurrent hyperthyroidism. There was no significant difference in complication rates between TT and ST.

Results of subtotal thyroidectomy for Graves' disease

The objective of this study was to find the factors responsible for hypothyroidism after subtotal thyroidectomy for Graves' disease. Two hundred five patients who were operated on from July 1989 to December 1997 were studied. The mean age of patients was 33.4+/-11.0 (mean +/- SD) years, and 175 (85.4%) were female. Patients were prepared with an antithyroid drug and Lugol's solution preoperatively. Triiodothyronine (T3), thyroxine (T4), thyrotropin (TSH), thyrotropin-binding immunoglobulins (TBII) antimicrosomal antibodies (AMA = 100x 4(M-1)), and antithyroglobulin antibodies (ATA = 100x4(T-1)) were measured 1 week before patients were operated on. Operations were performed according to the standard procedure with 2.5x1x1 cm of thyroid tissue remaining on each side before approximating the thyroid capsule and pretracheal fascia. Hypothyroidism was defined by patients with overt hypothyroidism in laboratory data, and or with T4 to maintain T3 and T4. Two hundred two patients were checked 3 months after being operated on. Latent hyperthyroidism was found in 22, euthyroidism in 55, latent hypothyroidism in 91, hypothyroidism in 34 (16.8%) and none were in overt hyperthyroidism. After a follow-up period of 26.9+/-15 (mean +/- SD) months, 199 patients were reevaluated. Overt hyperthyroidism was found in 2 patients, latent hyperthyroidism in 12, euthyroidism in 97, latent hypothyroidism in 72, and hypothyroidism in 16 (8%). Factors having possible effects on hypothyroidism after longterm follow-up were analyzed. Patient's age, gender, body surface, premedicative T3 and T4, preoperative ATA, and TBII, and the weight of removed thyroid had no effect on the occurrence of hypothyroidism. Preoperative AMA levels, and finding more than 10 lymphoid infiltrations per 10 low-power fields (x40) were significantly different between the hypothyroid and nonhypothyroid groups. A high level of preoperative AMA was the only factor independently causing overt hypothyroidism in the follow-up period. Patients with high preoperative AMA levels have a higher risk of hypothyroidism if only 2.5x1x1 cm remnants are left on each side.

Factors affecting thyroid function after subtotal thyroidectomy for Graves' disease: case control study by remnant-weight matched-pair analysis

In order to determine whether there are any predictive factors, other than the amount of remnant thyroid tissue, for subsequent thyroid function after subtotal thyroidectomy for Graves' disease, thyroid function was assessed in 329 patients 3 years after surgery, and a case control study was carried out in euthyroid, hyperthyroid, and hypothyroid groups by remnant-weight matched-pair analysis. Factors that affected thyroid function 3 years after surgery were thyroid gland infiltration by lymphocytes and the thyrotropin binding inhibiting immunoglobulin (TBII) value in the hyperthyroid and euthyroid groups, and the free triiodothyronine (FT3) value at the time of surgery and lymph follicle formation in the thyroid gland in the hypothyroid and euthyroid groups. It is concluded that no single factor studied at surgery, other than the amount of remnant tissue, can predict thyroid function after subtotal thyroidectomy for Graves' disease.

Early recurrence of hyperthyroidism in patients with Graves' disease treated by subtotal thyroidectomy

Prerequisites for surgical treatment of Graves' disease are that it can be done safely and that it is associated with a low incidence of recurrent hyperthyroidism. Early recurrence is especially undesirable. We studied 728 patients with Graves' disease treated by subtotal thyroidectomy using multivariate analysis in order to determine the factors related to early recurrence. The following factors were analyzed: age, sex, duration of medical treatment, weight of resected thyroid tissue, thyroid remnant size, preoperative level of thyroid-stimulating hormone (TSH) binding inhibitory immunoglobulin (TBII), and antimicrosomal hemagglutination antibody (MCHA). "Early recurrence" was defined as TSH suppression observed within the first year after surgery and continuing for at least 6 months. A total of 106 patients (14.6%) had early recurrence. Statistical analyses were performed by the chi-square test for univariate analysis and a logistic model for multivariate analysis. Significant factors were thyroid remnant size, MCHA, and TBII. These results indicated that TBII and MCHA are related to early recurrence of hyperthyroidism, and smaller remnant size is recommended for patients with a high MCHA titer or a high TBII level (or both) in order to avoid early recurrence.

Management of recurrent hyperthyroidism in patients with Graves' disease treated by subtotal thyroidectomy

If the aim of surgical treatment for Graves' disease is not permanent hypothyroidism, it is difficult to avoid recurrent hyperthyroidism completely. The management of recurrent hyperthyroidism, however, is neither easy nor obvious. Improvement in the sensitivity of TSH assay has allowed the diagnosis of latent hyperthyroidism. Little is known about the clinical course of latent hyperthyroidism. We studied the management and outcome of recurrent hyperthyroidism in patients with Graves' disease treated by subtotal thyroidectomy. Between January 1988 and August 1991, 1115 patients with Graves' disease were treated by surgery. Postoperative thyroid function was evaluated by free T3, free T4 and TSH measurements. One hundred seventy-five patients with suppressed TSH secretion for at least 6 months were categorized as having recurrent hyperthyroidism. Eighty patients (45.1%) also had elevated thyroid hormone levels, (group 1). The remaining 95 patients (54.9%) had normal thyroid hormone levels with suppressed TSH values (group 2). In group 1, 58 patients were treated with antithyroid drug (ATD), 12 with iodine and 10 with radioiodine (RI). Remission of Graves' disease was obtained in 22 patients (11 by ATD, 1 by iodine and 10 by Ri). On the other hand, patients in group 2 were followed up without medication, and spontaneous remission was observed in 21 of theln (22.1%). It was difficult to induce remission of overt recurrent Graves' disease by ATD or iodine. In contrast spontaneous remission could be obtained in some patients with postoperative latent hyperthyroidism.

Follow-up evaluation of patients with Graves' disease treated by subtotal thyroidectomy and risk factor analysis for post-operative thyroid dysfunction

Eight-year follow-up evaluation and analysis of factors related to postoperative thyroid dysfunction were made in 216 patients with Graves' disease treated by subtotal thyroidectomy. The postoperative status of thyroid function were as follows according to hypersensitive TSH level: 65 patients (30.1%) were euthyroid, 25 (11.5%) had overt hyperthyroidism requiring treatment, 14 (6.5%) had subclinical hyperthyroidism with normal thyroid hormone and suppressed TSH, 21 (9.8%) were overt hypothyroid requiring thyroid hormone replacement and 91 (41.1%) had latent hypothyroidism without hormone replacement. In order to know factors related to postoperative thyroid function, age, sex, preoperative levels of TSH receptor antibody (TRAb), thyroid antibody titers, degree of lymphocyte infiltration, duration of medical treatment, weight of the resected thyroid tissue and weight of the remnant thyroid tissue were determined. No factor except thyroid remnant and antimicrosomal antibody titer was related to postoperative thyroid function. The weight of remnant should be less than 6 g to avoid recurrent hyperthyroidism. As recurrence of hyperthyroidism was observed more than 5 yr after surgery, long follow-up is needed.

Retrospective analysis of prognostic factors affecting the thyroid functional status after subtotal thyroidectomy for Graves' disease

To determine the factors causing thyroid dysfunction after surgery for Graves' disease, we studied 321 patients who underwent subtotal thyroidectomy during the 7-year period from 1981 to 1987. Thyroid functional status was evaluated biochemically and the patients were divided into four categories: recurrent hyperthyroidism, euthyroidism, latent hypothyroidism, and hypothyroidism. The following factors were analyzed: sex, age at onset of the disease, indication for surgery, serum titer of antimicrosomal hemagglutination antibody (MCHA), weight of resected thyroid tissue, size of remnant thyroid relative to body surface area, pathological findings of lymphoid follicles, and lymphocytic infiltration in the thyroid tissue. Probabilities of failure (recurrent hyperthyroidism and hypothyroidism) were estimated by the Kaplan-Meier method. Prognostic factors for failure were identified by using Cox's proportional hazards model. The incidence of hyperthyroidism and hypothyroidism 5 years after subtotal thyroidectomy was 16.2% and 9.6%, respectively. Significant factors for hyperthyroidism were relatively large thyroid remnant, high serum titer of MCHA (greater than or equal to 1:3200), and age at onset of the disease less than 20 years. The significant factor for hypothyroidism was severe lymphocytic infiltration. The level of postoperative thyroid stimulating hormone (TSH)-binding inhibition immunoglobulins (TBII) in patients with recurrence was significantly higher than in patients in remission. It is reasonable to determine the amount of remnant thyroid tissue in relation to patient body surface area. Although subtotal thyroidectomy can induce immunological remission by reduction of antigen, if the remission disappears, that is if TBII increases, recurrence of hyperthyroidism may develop even in patients without the unfavorable factors.

Natural course of Graves' disease after subtotal thyroidectomy and management of patients with postoperative thyroid dysfunction

The Natural course of Graves' disease after subtotal thyroidectomy was studied in 67 patients who had subtotal thyroidectomy for Graves' disease and did not receive any medical treatment for 8 to 12 years after surgery. Postoperative thyroid status was determined by serum free thyroxine (T4), free triiodothyronine (T3), and thyrotropin (TSH) levels in the first period (1 year after surgery), second period (3.9 +/- 1.0 years), and third period (8.8 +/- 1.5 years). Serum thyroid stimulating antibody (TSAb) and TSH binding inhibitor immunoglobulin (TBII) activities were also measured. A total of 53 patients (79%) changed thyroid status during the observation period. One year after surgery, 50 percent of euthyroid subjects developed abnormal thyroid function in the next period. Reversible latent hypothyroidism was the most common type of thyroid dysfunction seen in up to 46% of patients. Interestingly, hyperthyroidism and hypothyroidism that developed in the postoperative period were temporary disorders in most cases. Serum TSAb and TBII activities did not help predict the postoperative changes of thyroid status. Our study indicates that the instability of the thyroid function is common after subtotal thyroidectomy.