Iodized salt improves the effectiveness of L-thyroxine therapy after surgery for nontoxic goitre: a prospective and randomized study.
ABSTRACT 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.
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.
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.
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.
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ABSTRACT: Preliminary clinical studies and recent in vitro investigations suggest that iodine administration may be an effective alternative in the treatment of the diffuse euthyroid goitre of iodine deficiency. Therefore a 12-month multicentre study was initiated in which 166 patients were randomly assigned to take either 150 micrograms levothyroxine day-1 (group A, n = 61), 400 micrograms iodine day-1 (group B, n = 50), or a combination of 75 micrograms levothyroxine and 200 micrograms iodine day-1 (group C, n = 55) for 8 months with follow-up examinations at 4 and 8 months as well as 4 months after cessation of treatment. Initially, thyroid volume, as determined by ultrasound, was not significantly different in the three groups. In all three groups, during treatment a significant and comparable mean decrease in goitre size was documented (-32.1% in group A, -37.3% in group B, -38.7% in group C). After cessation of treatment in group A mean thyroid volume again increased to near the baseline value (-12.0% compared to the initial investigation), while the therapeutic effect was sustained in group B (-32.5%). In group C, only a slight rebound effect was observed (-26.3% vs baseline volume). Total thyroxine (T4) increased sharply and significantly in group A from 7.8 +/- 1.9 to 10.9 +/- 2.8 micrograms dl-1 after 8 months (P less than 0.001), but only slightly, although significantly in group B (from 7.8 +/- 1.5 micrograms dl-1 to 8.9 +/- 1.6 micrograms dl-1; P less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)European Journal of Clinical Investigation 01/1990; 19(6):527-34. · 3.37 Impact Factor
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ABSTRACT: To review evidence about thyroxine suppressive therapy in patients with thyroid nodules, including the clinical importance and natural history of nodules and the effects and potential side effects of thyroxine therapy. English-language articles published from 1986 to December 1996 were identified through searches of the MEDLINE database, selected bibliographies, and personal files. Randomized, controlled trials and nonrandomized trials of thyroxine suppressive therapy for solitary and predominantly solid thyroid nodules were reviewed. In most studies, nodule cytology was evaluated by fine-needle aspiration biopsy. Therapy was considered suppressive if suppression was documented by thyroid-stimulating hormone-releasing hormone tests or sensitive thyroid-stimulating hormone assays. Response was defined as a decrease of 50% or more in nodule size or volume; most recent studies measured nodule size by ultrasonography. The evidence suggests that thyroxine suppressive therapy fails to shrink most nodules: Only 10% to 20% of nodules responded to this treatment. Fine-needle aspiration biopsy is more reliable in distinguishing benign from malignant nodules. Recent studies suggest that spontaneous decrease in size with complete disappearance of thyroid nodules is not uncommon. No data show that thyroxine therapy arrests further growth in most existing nodules or prevents the emergence of new nodules. Postoperative thyroxine therapy does not seem to prevent recurrence of thyroid nodules except in patients with a history of radiation therapy. Potential adverse effects of long-term suppressive therapy include osteoporosis and heart disease. Patients with cytologically benign nodules are best followed without thyroxine treatment. Most benign nodules remain stable in size and remain benign when monitored for a long time. For nodules that increase in size, biopsy should be done again or surgery should be performed.Annals of internal medicine 04/1998; 128(5):386-94. · 13.98 Impact Factor
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ABSTRACT: To study the long-term outcome after thyroidectomy, 113 sporadic non-toxic goitre patients who underwent thyroidectomy in our hospital in the period 1974-1983, were studied. Five patients complained of recurrent goitre; a goitre was found on inspection and palpation in these five and in 15 others. There were no differences between the 20 patients with goitre and the 93 patients without goitre with regard to sex, age, duration of goitre, indication and type of thyroidectomy, postoperative thyroid hormone medication, period of follow-up, and T4, T3, or TSH plasma values at the time of follow-up examination. Twenty-three patients complained of voice changes since thyroidectomy. In a case control study, included in this follow-up study, 19 patients with goitre, i.e. thyroid size I and II as estimated by inspection and palpation (cases), and 16 patients without goitre, i.e. thyroid size OA and OB (controls), were studied in more detail. No difference between cases and controls was found in any of the above mentioned parameters that could explain the recurrence of goitre. Thyroid volume (median) was greater in the cases (34.1 ml, range 7.9-83.4) than in the controls (10.3 ml, range 2.5-48.7) (P less than 0.001), although a considerable overlap between the two groups was observed. One or more thyroid nodules were found in 89.5% of the cases and in 62.5% of the controls (NS). Serum thyroid growth stimulating immunoglobulin (TGI) was present both in cases (68%) and controls (50%). TGI was present in high titres in all five patients who complained about recurrent goitre.(ABSTRACT TRUNCATED AT 250 WORDS)Clinical Endocrinology 09/1989; 31(2):193-9. · 3.40 Impact Factor