One hundred and eighty euthyroid pregnant women were selected at the end of the first trimester of gestation on the basis of biochemical criteria of excessive thyroid stimulation, defined as supranormal serum thyroglobulin (TG > 20 micrograms/L) associated with a low normal free T4 index (< 1.23) and/or an increased T3/T4 ratio (> 25 x 10(-3)). Women were randomized in a double blind protocol into three groups and treated until term with a placebo, 100 micrograms potassium iodide (KI)/day, or 100 micrograms iodide plus 100 micrograms L-T4/day. Parameters of thyroid function, urinary iodine excretion, and thyroid volume were monitored sequentially. Neonatal thyroid parameters, including thyroid volume by echography, were also assessed in the newborns from mothers of the three groups. In women receiving a placebo, the indices of excessive thyroid stimulation worsened as gestation progressed, with low free T4 levels, markedly increased serum TG and T3/T4 ratio. Serum TSH doubled, on the average, and was supranormal in 20% of the cases at term. Urinary iodine excretion levels were low, around 30 micrograms/L at term. The thyroid volume increased, on the average, by 30%, and 16% of the women developed a goiter, confirming the goitrogenic stimulus associated with pregnancy. Moreover, the newborns of these mothers had significantly larger thyroid volumes at birth as well as elevated serum TG levels. In both groups of women receiving an active treatment, the alterations in thyroid function associated with pregnancy were markedly improved. The increase in serum TSH was almost suppressed, serum TG decreased significantly, and changes in thyroid volume were minimized (group receiving KI) or almost suppressed (group receiving KI combined with L-T4). Moreover, in the newborns of the mothers in the two groups receiving an active treatment, serum TG was significantly lower, and thyroid volume at birth was normal. The effects of therapy were clearly more rapid and more marked in the group receiving a combination of T4 and KI than in the women receiving KI alone. The differences could be partly attributed to the slightly higher amount of iodine received by women in the combined treatment. However, the main benefits of the combined treatment were almost certainly attributable to the hormonal effects of the addition of L-T4. Furthermore, the study demonstrated that the administration of T4 did not hamper the beneficial effect of iodine supplementation. In conclusion, the present work emphasizes the potential risk of goitrogenic stimulation in both mother and newborn in the presence of mild iodine deficiency.(ABSTRACT TRUNCATED AT 400 WORDS)

The volume of the thyroid gland was determined by ultrasonography in 256 euthyroid subjects aged 0-20 years in Brussels, an area with borderline iodine intake (median urinary iodine: 6.8 micrograms/dl). The volume of each lobe was calculated separately using the formula of an ovoid (Depth x Length x Width x pi/6). The total thyroid volume was obtained by summation of the volume of both lobes. In neonates, mean volume (SD) was 0.84 (0.38) ml and the distribution was asymmetric, skewed towards elevated values (median: 0.76 ml); the volume was best correlated with body surface area (P less than 0.01). Thyroid volume significantly increased (P less than 0.001) until the age of 8 without being influenced by sex and thereafter varied widely: it increased from 2.7 (0.8) ml in prepubertal subjects aged 8-11 years to 11.6 (4.4) ml in late pubertal aged greater than 17 years. This increase was significantly correlated not only with chronological age but also with pubertal stage and seemed to happen early, with the onset of the first clinical signs of puberty. At all ages, the volume of the right lobe was slightly higher than the left lobe but the difference was not significant.

Objective: Interpretation of thyroid ultrasonography for assessing goiter prevalence requires valid reference criteria from iodine-sufficient populations. Reports have suggested the current reference criteria for thyroid volume (T vol ) of WHO/ICCIDD (International Council for the Control of Iodine Deficiency Disorders) may be too high. Our objective was to determine if inter-observer and/or interequipment variability contributes to the disagreement in sonographic T vol in children reported from iodine-sufficient areas. Design: A 2-day workshop in which four experienced ultrasound examiners from around Europe measured T vol in 45 6±12-year-old Swiss schoolchildren using four different portable ultrasound machines. One of the participating examiners (observer A) had generated the T vol data in European children that are the basis for the WHO/ICCIDD reference criteria. Methods: Sonographic T vol was measured in each child by all four examiners on all four machines. Six hundred and eighty-four examinations were completed, with examiners having no knowledge of one another's results. Inter-observer and inter-equipment variation was calculated. Results: Mean inter-equipment variation in T vol was 15.2% (95% CI: 14.1, 16.3%). There were no significant differences in T vol between equipment P 0X51X For all observers, the mean interobserver variation in T vol was 25.6% (95% CI: 23.9, 27.2%). At all ages and all body surface areas, there was a large systematic measurement bias (+30% volume) between the mean T vol of observer A and the mean T vol of observers B, C and D. Reanalysis using data from observers B, C and D reduced the mean inter-observer variation in T vol to 13.3% (95% CI: 11.9, 14.7%). A correction factor for the systematic difference of operator A for the P50 and P97 of T vol was estimated using analysis of covariance. When applied to the WHO/ICCIDD reference data, it sharply reduced the discrepancy between the WHO/ICCIDD criteria and those from other iodine-sufficient children around the world. Conclusions: Inter-equipment error contributes minimally to reported differences in sonographic T vol . Even among experienced examiners, inter-observer variation in sonographic T vol in children can be high, and probably contributes to the current disagreement on normative values in iodine-sufficient children. A systematic bias at least partially explains why the WHO/ICCIDD reference data differ from those reported from other iodine-sufficient children around the world. The findings argue strongly for the standardization of methods used for sonographic measurement of T vol in children.

Summary. The influence of maternal smoking during pregnancy on the function and the echographic volume of the neonatal thyroid gland was examined in an area of borderline iodine intake (median maternal urinary iodine: 315 range 79–1558 nmol/l). There was a positive correlation (P<0.001) between cord serum thiocyanate (SCN) concentrations used as an index of maternal smoking and the maternal smoking habits. The thyroid volume/birthweight ratio increased significantly as a function of SCN values (P<0.005): this increase was secondary to a decrease in birthweight as well as to an increase in thyroid volume. There was also a positive correlation between cord serum thyroglobulin (Tg) and SCN levels (P = 0.001). Serum thyroid‐stimulating hormone (TSH) and free thyroxine (FT4) values remained within the normal range for age in all newborn infants and were not significantly correlated with SCN values. These results show that smoking during pregnancy in areas with borderline iodine intake may be a significant cause of thyroid enlargement in the newborn.