| Hammer et al., Bochum, Germany, measured thyroid function parameters in 177 consecutive patients with first manifestations of atrial fibrillation in 1999 and 2000 and compared results with 336 matched controls without a history of atrial fibrillation. They found a serum TSH <0.01 mU/l in 7.3% of patients and in 3.3% of controls. These results indicate a 2.5-fold increased risk for atrium fibrillation in patients with subclinical hyperthyroidism as serum T4 and T3 were normal in subjects with low TSH. (Comment: The results of this study confirm earlier results published several years ago by Sawin et al., NEJM 1944;331: 1249. Furthermore, in a recent report Parle et al., Lancet 2001;358:861, showed that in persons =60 year, mortality from all causes is increased in particular mortality due to circulatory and cardiovascular diseases. In my mind there is no doubt that (elderly only?? I don't think so!) persons with subclinical hyperthyroidism should be treated effectively). Czarkowski et al., Warsaw, Poland, measured non-invasively arterial resistance in hyperthyroid patients with Graves' disease. They used a technique based on ultrasound that could measure vascular input impedance. Twenty-four patients were investigated and results were compared with 22 controls. They found that arterial resistance is depressed not only by a lowered tone of the arterioles but also a lowered resistance of the arteries. Changes in peripheral resistance were closely related to plasma thyroid hormone concentrations. Plazinska et al., Warsaw, Poland, studied the effect of lithium carbonate on thyroid uptake and biological- and effective half-life of administered 131I, in 128 patients with hyperthyroidism and a 24h 131-I uptake of <30%. They found that administration of lithium carbonate, started 3 days before uptake measurement and continued for 5 days, did increase 131I uptake in 106/128 patients, but irrespective of the effect on uptake, increased the biological- ( 5.8 to 267 days, p<0.001) and effective half-life of 131-I (6 to 7.8 days, p<0.001) in all 128 subjects. They found this effect to be present in subjects with Graves' disease, toxic adenoma and toxic multinodular goiter. The authors suggest that especially in patients with hyperthyroidism and low iodine uptake, administration of lithium carbonate enhances efficacy of iodine of 131-I treatment. Ogilvie et al., Cape Town, South Africa, randomly allocated 58 patients with untreated Graves' disease to treatment with carbimazole alone in reducing titrated doses and 48 patients to combined treatment of 40 mg carbimazole and thyroxine sufficient to suppress TSH. Both groups were treated for 12 months. In both treatment groups the relapse rate after one year was high (around 50%) and also in both groups risk to relapse was especially great if thyroid volume did not decrease during treatment. Zimmermann-Belsing et al., Copenhagen, Denmark, evaluated prospectively the insulin-like growth axis before and after 12 months of treatment of 24 female patients with Graves' hyperthyroidism. They did the study as patients with Graves' disease often complain of cognitive impairment, depression, severe fatigue and changes in body composition several months or years after obtaining euthyroidism, while these symptoms are often also seen in patients with growth hormone deficiency. They found that IGF-1, IGF-2 en IGFBP-3 decreased from levels in the high normal range before treatment, to the lower end of the normal range after treatment. Both total lean body mass and total bone mineral content were positively related to these parameters in the thyrotoxic state but not so after 12 months of antithyroid drug treatment. The authors conclude that the activity of the insulin-like growth axis is decreased in patients with Graves' disease after treatment resembling mild growth hormone deficiency (Comment: obviously it would be interesting to know if this decreased activity persist in subjects remaining euthyroid after treatment). |
