Ability of the rhTSH stimulation test to predict relapse in patients with differentiated thyroid carcinoma, after long-term follow-up.

The analysis of serum thyroglobulin (Tg) following thyroid-stimulating hormone (TSH) stimulation (sTg) has been recommended in the follow-up of differentiated thyroid carcinoma (DTC) patients, however, its routine use remains controversial. The aim of the current study was to evaluate the accuracy of sTg testing following recombinant human (rh) TSH stimulation in DTC patients, with a follow-up of 12.4 years. Retrospective studies were conducted of 125 DTC patients, who underwent rhTSH stimulation testing between 1999 and 2002. The exclusion criteria were: Patients with anti-Tg antibodies, Tg levels >1 ng/ml under TSH suppression and the absence of radioactive iodine (RAI) ablation therapy following surgery. In total, 49 patients were included in the study and all had been previously treated with total or near total thyroidectomy (with or without central neck dissection) and RAI, postoperatively. The Tg functional sensitivity was 1.0 ng/ml. The follow-up for patients was performed annually. During the median follow-up of 12.4 years after the rhTSH stimulation test, nine patients exhibited recurrence (18.4%). Of the nine patients, six exhibited sTg levels >2 ng/ml (positive result) and three exhibited levels <2 ng/ml (negative result). Relapse occurred at a mean of 5.9 years following the rhTSH stimulation test. The positive predictive value and negative predictive value (NPV) of positive sTg were 50 and 91.9%, respectively, with a sensitivity of 66.6% and a specificity of 85.0%. The rhTSH-stimulated Tg levels have a high NPV, allowing the identification of the patients who are free of the tumour. These results are consistent with the previously published data; however, to the best of our knowledge, this is the study with the longest follow-up duration after rhTSH stimulation.

[Iodine intake in Portuguese school children]. / Aporte do Iodo nas Crianças das Escolas em Portugal.

OBJECTIVE: The aim of the present study was to evaluate iodine intake in portuguese school children in order to inform health authorities of eventual measures to be implemented. INTRODUCTION: Iodine is the key element for thyroid hormone synthesis and its deficiency even mild, as found in other European countries, may have deleterious effects in pregnancy resulting in cognitive problems of offsprings. In Portugal there are no recent data on iodine intake in schoolchildren. POPULATION AND METHODS: 3680 children aged 6-12 years of both sexes, from 78 different schools were studied. Iodine intake was evaluated trough urine iodine (UI) determinations using a colorimetic method. RESULTS: The global median UI value was 105.5 µg/L; the percentage of children with UI <100 µg/L was 47.1%, corresponding to 41% of the studied schools. The percentage of values <50 µg/L was 11.8%. The male gender, the south region of the country and the distribution of milk in school were significantly linked with a higher iodine elimination. DISCUSSION: Our global results point to a borderline/ mildly insufficient iodine intake in the portuguese school population. However 47% of the children had UI under 100 µg /L. The comparison of our results with the available data from 30 years ago, point to a considerable improvement, due to silent prophylaxis. Male gender, geographical area and milk distribution influenced positively iodine intake.The importance of milk has been referred in numerous papers. CONCLUSIONS: The study of UI in the Portuguese school population points to a borderline iodine intake. However, in 47% of children iodine intake was inadequate. Compared with data from the eighties, a considerable increase in iodine elimination was found. Taking into account the potencial deleterious effects of inadequate iodine intake, a global prophylaxis with salt iodization has to be considered.

Serum vascular endothelial growth factor levels in patients with medullary thyroid carcinoma.

BACKGROUND: High levels of vascular endothelial growth factor (VEGF) have been reported in patients with cancers of different origins. There are no data comparing serum VEGF levels of medullary thyroid carcinoma (MTC) patients with that of the healthy subjects. OBJECTIVE: We tried to assess whether serum VEGF concentration in MTC patients is correlated with tumour extension and whether this marker might be used to further refine the selection of candidates for future therapies with receptor tyrosine kinase inhibitors. METHODS: Sera from 57 individuals divided into five groups: group I, healthy individuals (n=14); group II, MTC patients in remission (n=10); group III, MTC patients with residual disease (n=12); group IV, MTC patients with loco-regional disease (n=11) and group V, MTC patients with distant metastases (n=10) were analysed for serum VEGF and calcitonin (CT) levels. RESULTS: Analysis of serum VEGF did not disclose significant differences among the five groups. Mean serum VEGF level of patients with distant metastases was not significantly different from that observed in healthy individuals (319.4+/-49.78 vs 313.7+/-43.13 ng/l). Serum VEGF levels correlated positively with serum CT (r=0.4891; P=0.0394) for CT values below 2500 ng/l whereas there was no correlation for CT values above this threshold. CONCLUSIONS: Serum VEGF levels in MTC patients are not significantly different from those found in healthy individuals and did not correlate with the extension of disease.

In vitro assays to test the interference of anti-thyroglobulin antibodies on thyroglobulin measurement.

OBJECTIVE: To assess the interference of anti-thyroglobulin antibodies (TgAb) on serum thyroglobulin (Tg) measurement by in vitro experiments. Design Re-evaluation of Tg concentration after dilution with different TgAb-positive sera. On a first step, dilutions of the same Tg with different TgAb sera were performed and on a second step, different Tgs were diluted with the same TgAb serum. METHODS: Tg measurements were performed using an immunometric (IMA) chemiluminescence assay. TgAb measurements were performed using two methods: immunoflurimetric assay (UNICAP 100) and IMA chemiluminescent assay (IMMULITE 2000). RESULTS: Dilution of a known concentration of Tg with different TgAb-positive sera resulted in a variation of the final concentration of Tg ranging from -24 to -79%. A weak correlation was observed between the TgAb concentration and the percentage of the Tg deviation. Dilution of different Tgs with the same TgAb-positive serum illustrated how the same TgAb positive serum may determine a high interference or a neutral effect. CONCLUSIONS: Present results suggest that the interference on Tg measurement observed in the presence of TgAb may result not only from the anti-thyroglobulin antibodies, but also from the thyroglobulin itself.