Current status of iodine intake in Croatia--the results of 2009 survey

In 1996, due to persistence of mild to moderate iodine deficiency, new law on obligatory salt iodination with 25 mg of potassium iodide (KI) per kg of salt was implemented in Croatia. Along with a new law, a new program for monitoring of iodine prophylaxis was implemented. Investigations of goiter and iodine intake performed in 2002, demonstrated sufficient iodine intake in Croatia with overall median of urinary iodine concentration (UIC) for schoolchildren in Croatia of 140 microg/L. In 2002, thyroid volumes (TV) measured by ultrasound in schoolchildren from all four geographic regions of Croatia were for the first time within the normal range according to ICCIDD reference values. Nowadays, Croatia is internationally recognized as iodine sufficient country. The aim of the present study was to assess current status of iodine intake in Croatia. The investigation was carried out in 2009. A total of 386 schoolchildren aged 7-10 years from all four major geographic regions of Croatia, 103 euthyroid pregnant women and 36 women of child-bearing age from Zagreb, the capital, were included in the survey. Urinary iodine concentration (UIC) was measured in all participants. Thyroid volumes were measured by ultrasound in schoolchildren from the capital of Zagreb (N = 101) and the village of Rude (N = 56). In the time period 2002-2009, the content of KI was analyzed in 384 salt samples from Croatian salt plants and samples of imported salt. An overall median UIC for schoolchildren in Croatia was 248 microg/L. Median UIC in pregnant women was 159 microg/L, with 50% of samples below and under 150 microg/L. Median UIC in women of child-bearing age was 136 microg/L. Thyroid volumes in schoolchildren were within the normal range according to the new reference values. Mean value of KI/kg of salt in samples from Croatian salt plants was 25.5 mg/kg and 24.9 mg/kg in samples of imported salt. A total of 72/384 (18.8%) of salt samples didn't corresponded to the Croatian law on obligatory salt iodination. Presented data indicate sufficient iodine intake of the Croatian population. Current medians of UIC in schoolchildren in Croatia are significantly higher than medians measured in 2002. This indicates that other potential sources of iodine are present in Croatian diet that may contribute to overall iodine intake. Due to rising medians of UIC in schoolchildren in Croatia, it is important to conduct nutrition studies to identify potential sources of "silent prophylaxis" in order to avoid iodine excess.

Postoperative use of radioiodine (131-I): review of recommendations and guidelines

In the management of large number of patients with differentiated thyroid cancer, the radioactive iodine (131-I) administration plays an important role. The guidelines of numerous international and national medical societies regarding the issue of postoperative 131-I administration have been published and updated in the last few years. The guidelines differ in the shape and content, and contain some specific features. The different methods for evaluation and analysis of clinical evidence level and resulting grades of recommendations have been used in line with the very guidelines. The postoperative 131-I administration refers to the radioiodine ablation as a form of adjuvant treatment and radioiodine therapy in the management of patients with recurrent cancer, persistent disease and regional or distant metastases. According to the indications for the postoperative 131-I administration, the patients could be divided into the three risk groups: the very low risk group in which there is no indication for the postoperative 131-I administration, the low risk group in which the indication could be considered, and the high risk group in which there is a clear indication for the 131-I administration. The different criteria for distribution of patients into these three groups are expressed in a certain guidelines. There are different opinions about the necessary dosage of 131-I for the efficient ablation in the low risk group. Moreover, the opinions are also divided regarding the conduction of postoperative (preablative or pretherapeutic) scintigraphy with 131-I. As regards the instructions on preparation of patients for the radioiodine ablation and therapy, all the guidelines recommend the low iodine diet and endogenous or exogenous stimulation of TSH. The endogenous stimulation is accomplished by the withdrawal of thyroid hormones, whereas the recombinant human TSH (rhTSH) is used for exogenous stimulation. For conducting the therapy with 131-I the level of TSH has to be > 25-30 mU/L.

[Radioiodine versus surgery in the treatment of Graves' hyperthyroidism]

The most common etiologic cause of thyrotoxicosis in children and adults is autoimmune Graves' (Basedow's) disease. Antithyroid medications, surgery and radioactive iodine have been used in the treatment of Graves' hyperthyroidism for more than six decades. The use of antithyroid drugs is the most common therapeutic approach. However, long-term remission with antithyroid drugs can be expected in 20-50% of adults and 20-30% of children. The methods for definitive treatment of Graves' hyperthyroidism are iodine-131 (radioiodine) and surgery. Both treatment modalities have benefits and risks and the decision is made according to the age, patient preference and the presence of other co-morbidities, individual characteristics of patients and the availability of certain treatment modality. Radioiodine is simple, safe, effective and economic procedure for definitive treatment of Graves' hyperthyroidism. It is administered ambulatory and can be given to the patient in thyrotoxicosis. Due to many benefits, radioiodine is preferred in most of the adult patients with Graves' hyperthyroidism while only small proportion of patients is sent to surgery. Radioiodine is especially the treatment of choice in elderly patients and patients with heart disease. In these patients radioiodine is indicated immediately after reaching euthyroidism with antithyroid drugs. Surgery is mainly indicated in younger patients, in the case of patient preference or in special indications. Clear indications for surgical treatment of Graves' hyperthyroidism are: suspected or confirmed malignancy, coexisting pathology that demands surgical treatment, pregnancy and breastfeeding, large goiter (> 80 grams) or goiter with symptoms and signs of compression, severe toxic side effects of antithyroid medications, requirement for immediate control of disease, age younger than 5 years and active ophtalmopathy. The risk of surgical treatment is negatively correlated with the surgeon's experience and nowadays, total or near-total thyroidectomy is preferred surgical approach. End point of both treatment modalities is usually hypothyroidism that should not be considered as the consequence of treatment. Moreover, due to thyroid hormones replacement therapy equilibrium can be easily achieved.

Thyroid nodularity--true epidemic or improved diagnostics

The incidence of thyroid nodules has been rising steadily during the last 30 years, since the introduction of new diagnostic methods such as ultrasonography and computerized tomography, thus posing a real challenge in determining the best approach strategy for treatment of this new 'epidemic'. We analyzed and compared data from several studies showing the prevalence of thyroid nodules on autopsy, palpation and ultrasonography to be 13%-60%, 0.5%-6.5% and 13.4%-46%, respectively. This demonstrates that thyroid ultrasonography is a very sensitive and accurate diagnostic tool the use of which, however, entails an increased number of incidentally discovered thyroid nodules without clinical significance. Therefore, ultrasonography of the thyroid should not be performed without clinical indication determined by thyroid specialist.

Iodine supplementation in pregnancy

People of all ages can be affected by iodine deficiency, however, pregnant women and children are especially at a high risk. Because of changes that occur in maternal thyroid hormone economy during pregnancy and the potential unfavorable effects of iodine deficiency on the offspring, an adequate dietary iodine intake throughout the pregnancy is highly important. Therefore, the World Health Organization, United Nations Children's Fund and International Council for the Control of Iodine Deficiency Disorders have proposed that dietary intake of iodine during pregnancy should be 200-300 microg/day to compensate for the augmented T4 requirements in pregnant women. It has been shown that in countries with a longstanding and well-established universal salt iodination program where iodine sufficiency has been reached, there is a fraction of pregnant women that still have low median urinary iodine concentration, which indicates insufficient dietary iodine. Studies performed in such countries emphasize that pregnant women should use multivitamin and/ or mineral tablets specifically prepared for the needs of pregnancy and containing iodine supplements. Only the United States of America and Canada have official recommendations concerning iodine supplementation. In other countries, no such firm decisions have yet been made by medical community and public health authorities. In Croatia, an iodine sufficient country, the situation is the same. There is a need to collect adequate data on iodine supplementation and urinary iodine during pregnancy, along with the universal salt iodination program, so that definitive conclusions can be made.