Abstract. In the treatment of endemic goitre, the concept of giving levothyroxine in combination with iodine offers a promising therapeutic approach by influencing not only TSH secretion but also intrathyroidal iodine content. However, little is known about the doses of iodine necessary to correct intrathyroidal iodine deficiency. To get more information on this important issue, we conducted a prospective, double-blind study on the effect of a monotherapy with 500 μg iodide/day and a combined treatment with 100 μg levothyroxine and 100 μg iodide/day on thyroid iodine concentration as measured by fluorescence scintigraphy. In a group of 12 patients, a 4-month treatment with 100 μg levothyroxine and 100 μg iodide/day did not significantly affect thyroid iodine concentration (0.35±0.14 vs 0.37±0.11 mg/g). The application of 500 μg iodide/day in these patients during a second 4-month period resulted in a sharp increase in thyroid iodine concentration from 0.37±0.11 to 0.61±0.14 mg/g (p<0.01). Another group of 8 patients first treated with 500 μg iodide/day also showed a significant increase in iodine concentration from 0.35±0.14 to 0.65±0.20 mg/g (p<0.01). After switching to the combination regimen during a second 4-month period, thyroid iodine concentration slightly decreased, particularly in those patients with high iodine concentrations after monotherapy with iodide (0.65±0.20 vs 0.50±0.12 mg/g, p<0.05). In conclusion, treatment with 500 μg iodide/day could sharply increase thyroid iodine concentration in patients with endemic goitre. In contrast, a combination of 100 μg levothyroxine and 100 μg iodide/day had no significant effect on thyroid iodine concentration.
The aim of this study was to assess the results of high-dose radioiodine therapy given to 43 patients with recurrent hyperthyroidism due to Graves' disease between 1986 and 1992. We chose an intrathyroidal absorbed dose of 300 Gy and determined the applied activity individually, which ranged from 240 to 3120 MBq with a median of 752 MBq. Hyperthyroidism was eliminated in 86% of cases after 3 months and in 100% after 12 months. No patient required a second radioiodine treatment. The incidence of hypothyroidism was 63% after 3 months and 93% after 18 months. Neither the pretherapeutic thyroid-stimulating immunoglobulin level nor the degree of co-existing endocrine ophthalmopathy was correlated with the time at which hypothyroidism developed. Patients with previous radioiodine therapy developed hypothyroidism earlier than patients with previous thyroid surgery. The results show that ablative radioiodine therapy with a 300-Gy absorbed dose is a very effective treatment of hyperthyroidism in Graves' disease, but it should be restricted to patients with recurrent hyperthyroidism combined with severe co-existing disorders or episodes of unfavourable reactions to antithyroid drugs.
Using the 133Xe-DSPECT technique, quantitative measurements of regional cerebral blood flow (rCBF) were performed before and after provocation with acetazolamide (Diamox) i. v. in 32 patients without evidence of brain disease (normals). In 6 cases, additional studies were carried out to establish the time of maximal rCBF increase which was found to be approximately 15 min p. i. 1 g of Diamox increases the rCBF from 58 ±8 at rest to 73±5 ml/100 g/min. A Diamox dose of 2 g (9 cases) causes no further rCBF increase. After plotting the rCBF before provocation (rCBFR) and the Diamox-induced rCBF increase (reserve capacity, Δ rCBF) the regression line was Δ rCBF = −0,6 x rCBFR +50 (correlation coefficient: r = −0,77). In normals with relatively low rCBF values at rest, Diamox increases the reserve capacity much more than in normals with high rCBF values before provocation. It can be expected that this concept of measuring rCBF at rest and the reserve capacity will increase the sensitivity of distinguishing patients with reversible cerebrovascular disease (even bilateral) from normals.
Radioiodine therapy (RITh) is an effective mode of treatment of different types of hyperthyroidism (immunogenic, IH; nonimmunogenic, NIH). The aim of this study was to evaluate the risk of thyroid storm after RITh. For this purpose a systematic determination of thyroid hormones (TT3, TT4) 5 and if possible 12 days after RITh was performed in 416 patients with borderline or overt hyperthyroidism. Additional antithyroid medication after RITh was necessary in 20 patients. Among the remaining 396 patients 48% had been pretreated with antithyroid drugs because of more severe clinical symptoms. This medication was canceled 10 to 5 days before RITh in all cases. After RITh the mean TT3 and TT4 levels of the subgroups, with and without antithyroid premedication, decreased nearly in parallel course. The whole group of 396 patients presented a significant decrease in TT3 levels with a mean from 1.9 to 1.4 ng/ml. In 18 cases (5%) an increase in TT3 level (greater than or equal to 0.5 ng/ml) was detected without requiring antithyroid therapy. No case of thyroid storm was observed in the entire patient group. TT3 decrease appeared to be more pronounced in patients with higher pretreatment levels. TT4 showed a significant decrease only in case of elevated levels. Post-therapeutic hormone levels were not dependent on the etiology of hyperthyroidism (IH, NIH). The decrease of TT3 levels in the IH group was more pronounced after application of 150 Gy compared with 60 Gy. The additional medication with propranolol (greater than or equal to 60 mg/day) enforced the TT3 decrease. Accompanying glucocorticoid medication had no influence on the hormone levels.(ABSTRACT TRUNCATED AT 250 WORDS)
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