Preventive effect of levothyroxine in patients operated for non-toxic goitre: a randomized trial of one hundred patients with nine years follow-up

Long-Term Effects of 0.1 mg Recombinant-Human-Thyrotropin-Stimulated Fixed-Dose Radioiodine Therapy in Patients with Recurrent Multinodular Goiter after Surgery

(1) Background: After thyroid malignancy is ruled out, treatment options for multinodular goiter patients include surgery, levothyroxine suppressive therapy, and 131-I therapy. Surgery effectively reduces goiter size but carries risks of surgical and anesthetic complications. 131-I therapy is the only nonsurgical alternative, but its effectiveness diminishes with goiter size and depends on iodine sufficiency. This study aimed to assess the efficacy and safety of 0.1 mg rhTSH as an adjuvant to a fixed dose of 131-I therapy in patients with a recurrence of large multinodular goiter, several years after the initial thyroidectomy. (2) Methods: 14 patients (13 females and 1 male), aged 59.14 ± 15.44 (range, 35-78 years) received 11mciu of 131-I, 24 h after the administration of 0.1 mg rhTSH. The primary endpoint was the change in thyroid volume (by ultrasound measurements) as well as in the diameter of the predominant nodule during a follow-up period of 10 years. Secondary endpoints were the alterations in thyroid function and potential adverse effects. (3) Results: A significant decrease in the volume of initial thyroid remnants (32.16 ± 16.66 mL) was observed from the first reevaluation (at 4 months, 23.12 ± 11.59 mL) as well as at the end of the follow-up period (10 years, 12.62 ± 8.76 mL), p < 0.01. A significant reduction in the dominant nodule was also observed (from 31.71 ± 10.46 mm in the beginning to 26.67 ± 11.05 mm). (4) Conclusions: Further investigation is needed since this approach could be attractive in terms of minimizing the potential risks of reoperation in these patients.

Which Is the Ideal Treatment for Benign Diffuse and Multinodular Non-Toxic Goiters?

Patients with large benign goiters often present local compressive symptoms that require surgical treatment, including dysphagia, neck tightness, and airway obstruction. In contrast, patients with such goiters who remain asymptomatic may be observed after exclusion of malignancy. The use of levothyroxine (LT4) to reduce the volume of the goiter is still a controversial treatment for large goiters, and the optimal surgical procedure for multinodular goiter is still debatable. Radioiodine is a safe and effective treatment option when used alone or in combination with recombinant human TSH. This review discusses current therapeutic options to treat diffuse and multinodular non-toxic benign goiters.

Histopathological evaluation of recurrent goiter

The recurrent goiter is the regrowth of thyroid tissue after thyroidectomy. An inadequate surgical removal of the thyroid gland, lack of substitution therapy and pathological stimulation of the thyroid growth can all promote the recurrence. The aim of this study was to find the connection between the histopathological findings during the first and second operation and the recurrence of goiter. The study group consisted of 29 women and 1 man. The mean time to recurrence was 15 years. The most frequent histopathological finding during the first and second operation was struma nodosa. According to our observations different histopathological findings were found in 63.4% cases after primary and secondary thyroidectomy. Some genetic investigations showed that nodules in recurrent goiters did not derive from nodules left during the first operation but from a group of cells which had high growth potential. Thus, not only the operation technique and substitution after operation are key factors of successful therapy of goiter, but also other factors which stimulate the re-growth of thyroid tissue.

Levothyroxine therapy in preventing nodular recurrence after hemithyroidectomy: a retrospective study

AIM

To determine the effect of levothyroxine (L-T4) therapy on the recurrence rate of nodular disease in patients previously treated with lobectomy for benign nodular goiter.

METHODS

Two hundred and thirty-tree patients (38 males, 195 females; age 49.9+/-13.1 yr) with no post-surgical evidence of nodular disease in the remnant, were followed- up yearly with serum TSH and ultrasound (US). Nodular recurrence was defined as a lesion of at least 5 mm at US. Patients were divided in 2 groups based on whether or not they had been treated with L-T4 after surgery: Group 1 (45 patients) who did not receive any L-T4, and Group 2 (188 patients) treated with L-T4. Group 2 was further subdivided in Group 2a (123 patients) receiving L-T4 substitutive therapy (TSH>or=0.5 and <or=3 mUI/l) and Group 2b (65 patients) receiving L-T4 at TSH-suppressive dose (TSH<0.5 mUI/l).

RESULTS

Mean observation period was 5.8+/-4.7 yr. Overall, 71 out of 233 (30.5%) patients experienced recurrence of thyroid nodular disease: 29 patients (64.4%) in Group 1, 24 (19.5%) patients in Group 2a, and 18 (27.7%) patients in Group 2b. The recurrence rate was significantly lower (p<0.001) in Group 2 compared with Group 1, but no significant difference was observed between Groups 2a and 2b.

CONCLUSION

In patients who have undergone hemithyroidectomy for benign monolobar nodular disease, L-T4 therapy may prevent recurrence of nodular disease. TSH suppression may not be required for prevention of recurrence in the remnant thyroid tissue.

Radioiodine treatment for benign thyroid diseases

Radioiodine has been in use for over 60 years as a treatment for hyperthyroidism. Major changes in clinical practice have occurred with the realization that accurate dosimetry is incapable of avoiding the risks of hypothyroidism, while more accurate assessment of the risks of other adverse effects of radioiodine such as ophthalmopathy and carcinogenesis have become available. More is also known of the potential for pretreatment with an antithyroid drug to affect the outcome of radioiodine treatment. However, we are still uncertain of the benefits of radioiodine treatment in subclinical hyperthyroidism. During the last two decades there has been wider acceptance of radioiodine as a safe and effective therapy for benign, nontoxic goitre, coupled with waning enthusiasm for the use of levothyroxine, as the risks and benefits of this option have become more apparent. The use of recombinant TSH offers the prospect that radioiodine treatment of nontoxic goitre can be simplified and improved, although more studies of this strategy are urgently required.

Detecting and defining hypothyroidism after hemithyroidectomy

BACKGROUND

The incidence of hypothyroidism after hemithyroidectomy for benign thyroid disease remains uncertain. This study examines the incidence, natural history, and the factors contributing to hypothyroidism after hemithyroidectomy.

METHODS

A retrospective review of patients undergoing hemithyroidectomy over 37 months was performed. The incidence of postoperative hypothyroidism was based on thyrotropin values and clinical symptoms. The relationship between hypothyroidism and lymphocytic infiltration of the removed gland was investigated using stepwise logistic regression.

RESULTS

Twelve of 66 patients (18%) became biochemically hypothyroid postoperatively. Four of the 12 patients (33%) subsequently became euthyroid without intervention. Of the remaining 8 patients, 4 (50%) had significant lymphocytic infiltration in the resected gland compared with 10 (19%) of the 54 euthyroid patients. Lymphocytic infiltration was associated with hypothyroidism but was age dependent.

CONCLUSIONS

A minority of patients become hypothyroid after hemithyroidectomy. Some patients with biochemical hypothyroidism will become euthyroid without intervention. The impact of lymphocytic infiltrate on hypothyroidism after hemithyroidectomy is age dependent.

Comparison of the complications of subtotal, near total and total thyroidectomy in the surgical management of multinodular goitre

Purpose of the study is to compare complication rates of bilateral subtotal (BST), near total (NTT) and total thyroidectomy (TT) in a cohort of patients undergoing surgery for benign multinodular goitre (MNG). Seven hundred and fifty patients undergoing surgery for MNG were studied with a median follow-up of 53 months (range 18-102). There was no operative mortality in this group and no patients required urgent re-exploration for haematoma. After BST 14 patients (14/170 - 8.2%) developed transient hypocalcaemia and 4 patients (4/170 - 2.4%) had transient and one permanent (1/170 - 0.6%) recurrent laryngeal nerve (RLN) palsy. In NTT group 39 patients (39/320 - 12.2%) developed transient hypocalcaemia and 2 patients (0.6%) transient voice disturbances. None of the patients in this group experienced permanent complications. However, in TT group 78 patients had (78/260 - 30%) transient hypocalcaemia whereas only one patient (1/260 - 0.4%) suffered permanent hypoparathyroidism and 5 patients (5/260 - 1.9%) had temporary RLN injury but none of them remained permanent. There are only 2 (2/170 - 1.2%) recurrences and those patients are in BST group. All of the patients in BST group required at least 100 microg of thyroxine supplementation following the operation. These results demonstrate low permanent complication rates following thyroid surgery. Although the incidence of transient hypoparathyroidism increases with the extent of the resection, permanent complication rates are similar for all three surgical procedures. Even with short follow-up, there is a risk of recurrence with BST and therefore NTT or TT may be the operation of choice for MNG.

Risk factors for recurrent nodular goiter after thyroidectomy for benign disease: case-control study of 244 patients

Surgery for recurrent nodular goiter is associated with a significant risk of parathyroid and recurrent laryngeal nerve (RLN) morbidity. Total thyroidectomy for benign disease is assessed. The aim of this study was to evaluate the risk factors for recurrence and the morbidity associated with reoperation. From 1969 to 1996 a total of 4334 thyroidectomies were performed, of which 122 were for recurrent nodular goiter (group I: 116 women, 6 men). A matched case-control study of 122 patients operated on for nonrecurrent multinodular goiter was performed (group II: 112 women, 10 men). Age, family history, initial surgery, pathology, and morbidity were compared in the two groups by chi2 test, Fisher's exact test, and the Mantel-Haenszel test. The mean age was 39.88 years in group I and 47.89 years in group II. There was no statistical difference in relation to the extent of thyroidectomy or morbidity after initial surgery. Statistical differences were identified regarding age (p = 0.000002) and the multinodular nature of the initial goiter (p = 0.005). Bilaterality and family history were less significant (p = 0.09 andp = 0.08, respectively). Temporary RLN palsy and temporary hypoparathyroidism were higher in group I (12.3% vs. 5.7%,p = 0.0737; 10.6% vs. 1.7%, p = 0.00337). Permanent RLN palsy was found in 0.8% in group I and in none in group II (p = 0.5, NS). Young age and multiple nodules at initial surgery are risk factors for recurrence. A higher rate of temporary morbidity was demonstrated after surgery for recurrent goiter. Total thyroidectomy for multinodular goiter is advisable.

Predictive factors for recurrence after thyroid lobectomy for unilateral non-toxic goiter in an endemic area: Results of a multivariate analysis

BACKGROUND

The aim of the study was to identify the factors that are predictive of recurrence after thyroid lobectomy for unilateral non-toxic thyroid goiter in an endemic region through a multivariate analysis.

METHODS

Two hundred sixty-eight consecutive patients who underwent thyroid lobectomy and who were evaluated by the same endocrinologist were included. Univariate and multivariate analysis analyzed the relationship between sex, age, preoperative thyroid-stimulating hormone, duration of disease, duration of levothyroxine (LT4) preoperative therapy, cytologic results, histologic results, resected thyroid weight, numbers and diameters of thyroid nodules, morphologic alterations of the remnant lobe, follow-up length, postoperative LT4 therapy, ultrasonographic evidence of recurrence, and reoperation.

RESULTS

The incidence of recurrence was 33.9% (91/268 patients) after a mean follow-up time of 79.9 months (range, 12-251 months), female sex ( P = .016), multiple nodules ( P = .017), and lack of postoperative LT4 therapy ( P = .0009) were predictive factors of recurrence. Reoperation was performed in 20 patients (7.4%); factors that were predictive of reoperation were the presence of multiple nodules ( P = .008), resected thyroid weight ( P = .00006), and lack of postoperative hormonal therapy ( P = .0005).

CONCLUSIONS

Thyroid lobectomy for unilateral non-toxic goiter, when combined with suppressive or substitutive thyroxin therapy, resulted in a low rate of recurrence and reoperation in an endemic area.

Management of simple nodular goiter: current status and future perspectives

The simple nodular goiter, the etiology of which is multifactorial, encompasses the spectrum from the incidental asymptomatic small solitary nodule to the large intrathoracic goiter, causing pressure symptoms as well as cosmetic complaints. Its management is still the cause of considerable controversy. The mainstay in the diagnostic evaluation is related to functional and morphological characterization with serum TSH and (some kind of) imaging. Because malignancy is just as common in patients with a multinodular goiter as patients with a solitary nodule, we support the increasing use of fine-needle aspiration biopsy (cytology). Most patients need no treatment after malignancy is ruled out. In case of cosmetic or pressure symptoms, the choice in multinodular goiter stands between surgery, which is still the first choice, and radioiodine if uptake is adequate. In addition to surgery, the solitary nodule, whether hot or cold, can be treated with percutaneous ethanol injection therapy. If hot, radioiodine is the therapy of choice. Randomized studies are scarce, and the side effects of nonsurgical therapy are coming into focus. Therefore, the use of the optimum option in the individual patient cannot at present be based on evidence. However, we are of the view that levothyroxine, although widely used, should no longer be recommended routinely for this condition. Within a few years, the introduction of recombinant human TSH and laser therapy may profoundly alter the nonsurgical treatment of simple nodular goiter.

Iodized salt improves the effectiveness of L-thyroxine therapy after surgery for nontoxic goitre: a prospective and randomized study

OBJECTIVE

To investigate whether the addition of iodized salt to daily diet in thyroidectomized patients for nontoxic goitre could influence the effectiveness of nonsuppressive L-thyroxine (L-T4) therapy on thyroid remnant size, during 12 months' follow-up after thyroid surgery.

DESIGN AND PATIENTS

A consecutive series of selected 139 patients (26 males, 113 females; median age 45 years, range 30-69 years) living in a moderate iodine-deficient area, and undergoing thyroid surgery for nontoxic multinodular goitre, was enrolled. Patients were assigned randomly to two different therapeutic regimens: 70 patients received L-T4 therapy alone (Gr. L-T4), while the remaining 69 patients took iodized salt on a daily basis in addition to L-T4 treatment (Gr. L-T4 + I). In both groups, the initial L-T4 dose was 1.5 microg/kg/day, which, in our experience, has been shown to be intermediate between suppressive and replacement doses. To avoid the risks of mild thyrotoxicosis and to limit the excessive TSH stimulation of the thyroid remnant, the L-T4 dose was adjusted in those patients with serum TSH levels outside the lowest two-thirds of the normal range (0.3-2.5 mU/l). An ultrasound evaluation of thyroid remnant size was performed after thyroid surgery and 12 months later.

RESULTS

After surgery, the median thyroid remnant volume was 3.5 ml (range 0.4-13.9 ml) in Gr. L-T4 and 4.6 ml (range 0.5-12.7 ml) in Gr. L-T4 + I (P = 0.06). After 1 year of follow-up, the patients treated with L-T4 + I obtained a remnant volume reduction (-39.7%, range -87.0% to +91.2%) significantly (P = 0.006) greater than that observed in patients assuming L-T4 alone (-10.2%, range -89.4% to +85.0%). However, the percentage of patients showing an increase in remnant size in the months following surgery was higher in Gr. L-T4 than in Gr. L-T4 + I (22/60 vs. 9/66; P = 0.01). In Gr. L-T4 patients the thyroid remnant volume variation throughout 12 months of treatment was correlated significantly with the size of the thyroid remnant found at the first ultrasound evaluation (R(2) = 0.3; P < 0.001). No such correlation was found in Gr. L-T4 + I patients, for whom the therapy maintains a similar effectiveness in patients with either a large or a small postsurgery thyroid remnant. In patients treated with L-T4 alone, the remnant volume variation was correlated significantly with the median serum TSH values attained in the course of treatment (R2 = 0.4; P < 0.001). The highest reduction in remnant volume was observed only by lowering the serum TSH concentrations. In patients treated with L-T4 plus iodine, instead, the thyroid remnant volume reduction occurred independently of the plasma TSH levels attained in the course of treatment.

CONCLUSIONS

Our short-term prospective and randomized study leads us to conclude that, in patients living in a moderate iodine-deficient area and undergoing thyroid surgery for nontoxic goitre: (1) the iodine prophylaxis improves the effects of postsurgery nonsuppressive L-T4 therapy on thyroid remnant size. (2) In patients treated with L-T4 alone the therapeutic effectiveness decreases in the presence of a large postsurgery thyroid remnant. With the addition of iodine, the L-T4 maintains a similar efficacy in patients with either a large or a small remnant. (3) During treatment with L-T4 alone the highest therapeutic effectiveness is attained by lowering the plasma TSH concentration. With the addition of iodized salt to the daily diet the effects of L-T4 on remnant size are relevant independently of the TSH levels.

Long-term follow-up of contralateral lobe in patients hemithyroidectomized for solitary follicular adenoma

OBJECTIVES

Since there are no available conclusive studies on the long-term evolution of remnant thyroid tissue after hemithyroidectomy in patients who undergo surgery for solitary follicular adenomas, we searched for such cases in our records to elucidate this issue.

DESIGN

Search criteria were as follows: (i) presence of a single palpable thyroid nodule with the remainder of the gland normal on palpation; (ii) clinically euthyroid status at the time of surgery; (iii) histological diagnosis of nodule as follicular adenoma; (iv) a hemithyroidectomy operation, sparing the contralateral lobe; (v) normal macroscopic aspect of the contralateral lobe at the time of surgery; and (vi) at least 4 years of postoperative follow-up.

PATIENTS

Only 47 female cases were found to meet above criteria, with a mean age of 45.9 years (range: 23-79) at the time of surgery and a mean follow-up of 7.2 years (range: 4-32). Besides evaluating the presence or absence of antithyroid antibodies and the extranodular histology of tissue removed during surgery, a preoperative TRH test also allowed patients to be classified into two groups: normal extranodular thyroid (NET) (n = 32) and abnormal extranodular thyroid (AET) (n = 15).

RESULTS

Eleven of the 15 patients with AET had thyroid autoimmunity, with or without overt histological thyroiditis, and the remaining four had subclinical hypothyroidism with negative antithyroid antibody titres. In the entire study population, only 28 patients received treatment with L-T4 immediately after surgery, none of whom had any alterations in the contralateral lobe. However, six of the nineteen patients not treated with T4 (31.6%) developed overt abnormalities in the contralateral lobe, including the only three with AET who had not received L-T4 treatment. The remaining three were two patients with NET, who showed postoperative TSH hyper-responsiveness to TRH (peak TSH > 25 mU/l), and one who developed a new follicular adenoma 32 years later. To date, none of the patients with NET, who had a normal TRH test after surgery, have developed any kind of alterations in the contralateral lobe, even those who received no L-T4 prophylactic treatment.

CONCLUSIONS

The findings of this study suggest that: (i) there is a higher risk of follicular adenomas developing in a gland affected by thyroid autoimmunity than in a previously normal gland; (ii) L-T4 therapy may prevent the formation of new nodules or the development of goitre in the contralateral lobe; and (iii) in the absence of prophylactic treatment after surgery, the contralateral lobe of subjects with thyroid autoimmunity and/or previous subclinical hypothyroidism develops morphological abnormalities.

Postintervention serum TSH levels may be useful to differentiate patients who should undergo levothyroxine suppressive therapy after thyroid surgery for multinodular goiter in a region with moderate iodine deficiency

Recent studies have raised doubts about the efficacy of the postoperative use of levothyroxine (LT4) suppressive doses in patients who underwent thyroid surgery for multinodular goiter. The purpose of this retrospective study was to examine the efficacy of different doses of LT4 in preventing postsurgical recurrences of simple multinodular goiter and to identify a marker that could be useful in discriminating patients with a higher risk of developing recurrence. Two hundred thirty-two patients (57 male, 175 female) operated for nontoxic multinodular goiter were divided into two groups: (I) patients with normal postsurgery thyrotropin (TSH) levels (0.25 to 4.5 mU/L) and (II) patients with elevated postsurgery TSH levels (>4.5 mU/L). All patients were subjected to replacement (1.3 microg LT4/kg/day) or suppressive (1.7 microg LT4/kg/day) doses of LT4, and they were followed for a median period of 6 years (range 2 to 12). No statistical difference was found for sex, age, and postsurgery serum TSH between patients submitted to suppressive and replacement therapy. The ultrasound (US) detection of new postsurgery nodules of at least 0.5 cm maximum diameter was considered a recurrence of disease and was found in 10% of the cases studied. Patients with normal postsurgery serum TSH showed a high recurrence rate (30.4%) when submitted to lower daily doses of LT4. In patients with elevated postsurgery serum TSH, the rate of nodular goiter recurrence did not vary with different types of LT4 therapy. In conclusion, our results suggest that the postsurgical serum TSH is useful for prediction of nodular goiter recurrence, as it reflects the amount of residual functioning thyroid tissue in the cervical area. It may also be indicative of patients who might benefit from LT4 suppressive therapy.

Thyroid nodules: pathogenesis, diagnosis and treatment

Thyroid nodules are very frequently found and their prevalence steadily increases with age. The discovery of such lesions by high-resolution radiological imaging procedures that have been performed for other indications raises the problem of how incidentally discovered thyroid nodules should be investigated in a cost-effective manner to identify the rare patient with a clinically significant malignancy. In this review the clinical criteria that prompt the evaluation of thyroid nodules are discussed, as is the currently recommended diagnostic approach, which principally relies on fine needle aspiration biopsy. The clinical implications of the different cytological diagnoses are discussed, with a special emphasis on the management of indeterminate, microfollicular lesions. Finally, the evidence for and against suppressive thyroid hormone therapy for benign thyroid nodules and multinodular goitres is discussed, with particular consideration of high-risk patients with prior external radiation therapy to the neck region.

Multinodular goitre: 'much more to it than simply iodine deficiency'

For over a century, multinodular goitre (MNG) has been looked upon as the simple consequence of iodine deficiency. This view is now no longer tenable. Indeed, many characteristics of MNG do not fit with the iodine deficiency concept. For example, nodular goitre is a frequent disease even in those countries where the population is never exposed to iodine shortage. Moreover, neither multinodularity, nor the proverbial heterogeneity of growth and function or the autonomous, thyroid stimulating hormone (TSH)-independent growth of many goitres are compatible with the iodine deficiency concept, let alone subclinical or overt thyrotoxicosis which often complicates the course of a MNG. Recent investigations have led to the conclusion that MNGs are true benign neoplasias that are due to the high intrinsic growth potential of a variable, genetically predetermined fraction of all thyrocytes. Gross and heritable metabolic and functional differences between the individual thyrocytes, from which new follicles are generated during goitrogenesis, are the cause of the often spectacular functional and structural heterogeneity of MNG. Superimposed iodine deficiency changes the epidemiology, but not the basic mechanisms of goitrogenesis. These new pathogenetic concepts have a profound impact on the clinical management of MNG.

Hypothyroidisim following hemithyroidectomy: incidence, risk factors, and management

BACKGROUND

The purpose of this study was to characterize the hypothyroidism that occurs following hemithyroidectomy.

METHODS

The records of all euthyroid patients who underwent hemithyroidectomy from 1992 to 2000 were reviewed to determine the frequency of postsurgical hypothyroidism and the predisposing factors. All patients were evaluated for age, gender, serum thyrotropin (TSH) levels, weight of resected thyroid tissue, and associated thyroiditis. Hypothyroid patients were evaluated for symptoms, timing of diagnosis, and treatment doses of levothyroxine (L-T(4)).

RESULTS

Hypothyroidism was diagnosed in 25 (35%) of 71 patients, subclinical in 16 and overt in 9 with a mean postoperative TSH level of 8.51 +/- 6.53 microIU/L. The mean preoperative TSH level was 1.94 +/- 1.00 microIU/L in hypothyroid compared with 1.10 +/- 0.74 microIU/L in euthyroid patients (P <.05). Lymphocytic thyroiditis was present in 10 (40%) of 25 hypothyroid compared with 10 (22%) of 46 euthyroid patients (P = not significant). There were no significant differences in age, gender, or weight of resected thyroid tissue. The average therapeutic dose of L-T(4) was 1.3 microg/kg (range, 0.5 to 1.9 microg/kg). All but 2 hypothyroid patients were diagnosed within 2 months of operation.

CONCLUSIONS

Hypothyroidism following hemithyroidectomy occurs in patients with higher preoperative TSH levels, is usually mild and asymptomatic, and can be treated with reduced doses of L-T(4).

Postoperative Suppressive Therapy for Thyroid Adenomas

Thyroid adenoma is a common disease. If partial thyroidectomy is performed, postoperative suppression therapy is often given to avoid nodule development in the remaining thyroid. It is unclear whether this treatment is warranted. Patients who underwent a partial thyroidectomy with a histologic diagnosis of follicular thyroid adenoma from January 1985 until February 1998 were studied retrospectively. Patients were analyzed on the basis of postoperative therapy, new thyroid nodule growth, and costs. Seventy-six patients were identified with a recurrence rate of 4 per cent (3/76). Sixty-one per cent (46/76) were treated with postoperative thyroid suppression therapy, and no difference in new nodule development was noted with at least 6 months of follow-up ( P = 0.274). No patients required reoperation. A large cost saving was shown for patients who were not treated with levothyroxine. We conclude that postoperative thyroid suppression may not be routinely indicated. A prospective, randomized study would be necessary to answer this question conclusively.

Determinants of longterm outcome of radioiodine therapy of sporadic non-toxic goitre

OBJECTIVE

Radioiodine treatment is effective in reducing the size of sporadic nontoxic goitre, albeit at the expense of a high incidence of postradiation hypothyroidism. The decrease in goitre size, however, is not observed in all subjects, and little is known about recurrent goitre growth after 131I therapy. The aim of the present study was to evaluate which factors determine the longterm outcome of 131I treatment in patients with sporadic nontoxic nodular goitre, in terms of changes in both thyroid size and thyroid function.

STUDY DESIGN

Retrospective follow-up study.

PATIENTS

Fifty patients with sporadic nontoxic nodular goitre were evaluated who had been treated in our institution with 131I (mean dose 4.4 MBq/g thyroid) in the period 1988-95. Nine patients received a second dose of 131I and one a third. Median follow-up time was 41 months (range 24-115).

MEASUREMENTS

Thyroid function was assesed by TSH and FT4 index, and thyroid volume by ultrasound in 46 patients, by scintiscan using the Himanka formula in three and by CT-scan in one. The response to treatment was defined as a decrease in thyroid volume of greater than 13% (i.e. the mean + 2SD of the coefficient of variation of volume measurements), and recurrent goitre as an increase in thyroid volume greater than 13% after an initial response.

RESULTS

Goitre size decreased from a median value of 82 ml (range 17-325) to 37 ml (range 6-204) two years after 131I treatment, a median reduction of 49%. The decrease in goitre size was directly related to the dose of 131I (r = 0.50, P = 0.0003) and indirectly to baseline goitre size (r = - 0.35, P = 0.006). Seven patients (14%) were nonresponders, and four (8%) experienced recurrent goitre growth after 3-5 years. These 11 patients (22%) when compared to the remaining 39 responders (78%) had larger goitres with more often a dominant nodule, and had received a lower 131I dose. The efficacy of a second dose of 131I (median reduction in goitre size 37%) was comparable to the first dose. Hypothyroidism occurred in 24 patients (48%), mostly in the first two years after treatment; 11 had overt and 13 subclinical hypothyroidism. Kaplan Meier statistics indicated a probability of 58% for developing hypothyroidism after 8 years. Hypothyroid patients had a smaller initial goitre size and a higher prevalence of TPO antibodies and a family history of thyroid disease than the patients who remained euthyroid; the 131I dose did not differ between the two groups.

CONCLUSIONS

The size of sporadic nontoxic goitres is reduced on average by 50% after a single dose of 4.77 MBq 131I/g thyroid. Independent determinants of the relative decrease in thyroid volume are administered 131I dose and initial goitre size. Nonresponders (14%) and those with late recurrence of goitre growth (8%) have larger goitres and more often dominant nodules than responders. Determinants of postradioiodine hypothyroidism (cumulative risk 58% after 8 years) are the presence of TPO antibodies, a family history of thyroid disease and a relatively small goitre. The implications of these findings are that the efficacy of a given 131I dose can be enhanced when administered at an earlier stage when the goitre is still smaller, albeit at the expense of an increased risk for developing hypothyroidism.

Thyroid nodules in recurrent multinodular goiters are predominantly polyclonal

Not only thyroid adenomas and carcinomas, but also the majority of single and well delimited goiter nodules, even if morphologically heterogeneous, are of clonal origin. However, it is still unknown whether the nodules of rapidly growing, recurrent goiters are clonal or polyclonal. We investigated by PCR-based analysis of exon 1 of the human androgen receptor gene clonality of nodules grown in recurrent multinodular goiters (MNG) of 14 female patients. The total goiter volume varied widely between 15 ml and 170 ml. The mean age of patients undergoing surgery for recurrent goiter at the time of their first operation was significantly lower with 34.6 +/- 10.9 yr in comparison to 50 consecutive patients who were operated for MNG for the first time (53.7 +/- 13.5 yr). The interval between first and recurrent operation was 18 +/- 8.5 yr. The mean volume of well circumscribed nodules selected for the present investigation was 3.8 +/- 1.4 ml. Assessment of clonality in at least 2 samples of each lesion revealed a polyclonal pattern in 10 out of 14 nodules, whereas only 3 nodules were clonal and in one case the result remained unclear. The unexpected finding that most nodules within MNG, that had re-grown after a first subtotal thyroidectomy, were of polyclonal rather than clonal composition, suggests that these lesions are generated by de novo-proliferation of cohorts of differing thyrocytes sharing the common trait of an exceedingly high intrinsic growth rate or alternatively, by unknown growth stimulating molecular events acting focally on clusters of cells derived from different ancestors. In addition, the relatively young age of patients with recurrent MNG at the time of their first surgery and the comparatively short interval between first and second operation point to a genetic element in the occurrence of growth-prone thyrocytes.