On the occasion of the Krakow Declaration,1 the Área de Conocimiento del tiroides de la Sociedad Española de Endocrinología y Nutrición (TiroSEEN) [Thyroid Knowledge Area of the Spanish Society of Endocrinology and Nutrition] called attention to the iodine intake needs of the population.2 One of the measures this document recommends is the routine use of iodised salt to ensure that the majority of the population consumes adequate iodine and to put in place an epidemiological surveillance system to check that prevention measures are being complied with and are effective.1
Adequate iodine intake is known to ensure proper thyroid function, and is essential during pregnancy and breastfeeding. Most foods lack iodine, so dietary iodine supplementation is key.3,4 Unlike in other countries where the use of iodised salt is mandatory by law, in Spain it is not.5 There is also no regulation on iodised salt fortification of processed foods. As iodine deficiency is a global and easily preventable problem, TiroSEEN has provided guidelines on the subject.3 Fortunately, thanks to these efforts, iodine nutrition in Spain has improved in recent years, but target levels have not yet been reached.3
In order to assess compliance with European and TiroSEEN recommendations, we set out to analyse iodised salt consumption among patients attending the high-resolution thyroid nodule clinic at our hospital from April 2016 to October 2021; patients were asked about iodine consumption as part of their medical history. As our hospital is a referral centre, patients come from many different parts of Spain, although the majority of the sample comes from neighbouring areas. A total of 274 patients were interviewed. The results were grouped into three cohorts: regular users (RU), non-users (NU) and don't know if they use it (DK). In terms of baseline disease, there were patients with multinodular goitre (162), thyroid nodules (63) and cysts or thyroiditis without structural lesion (49) (Table 1).
Iodised salt consumption in patients seen in a thyroid nodule clinic.
| N (%) | Age (years; mean ± SD) | RU | NU | DK | |
|---|---|---|---|---|---|
| Total | 274 | 49.4 ± 13.7 | 107 (39.1) | 156 (56.9) | 11 (4.0) |
| Female | 199 (72.6) | 49.2 ± 13.9 | 84 (42.2) | 109 (54.7) | 6 (3.0) |
| Male | 75 (27.4) | 49.9 ± 13.2 | 23 (30.6) | 47 (62.6) | 5 (6.6) |
| Regions of origin | |||||
| Navarra | 59 | 28 (47.4) | 30 (50.8) | 1 (1.7) | |
| Basque Country | 42 | 17 (40.5) | 23 (54.7) | 2 (4.7) | |
| La Rioja | 28 | 13 (46.4) | 15 (53.6) | – | |
| Madrid Region | 18 | 2 (11.1) | 16 (88.8) | – | |
| Zaragoza | 9 | 6 (66.6) | 3 (33.3) | – | |
| Burgos | 9 | 3 (33.3) | 6 (66.6) | – | |
| Asturias | 7 | 1 (14.2) | 6 (85.7) | – | |
| Other | 102 | 37 (36.2) | 57 (55.8) | 8 (7.8) | |
DK: do not know if they use iodised salt; NU: non-regular iodised salt users; RU: regular iodised salt users; SD: standard deviation.
The conclusion was that, despite the recommendations of the SEEN and international scientific societies on the advisability of regular consumption of iodised salt, the rate for regular use among patients with nodular thyroid disease was around 40%. This proportion is higher among women, and there are probably significant differences between Spain's autonomous regions. Greater efforts are still needed to get the message across to the general population of the benefits of consuming iodine.