Correspondence

Persistence of Differences in Iodine Status in Newborns after the Reunification of Berlin

N Engl J Med 1995; 333:1429-1430November 23, 1995

Article

To the Editor:

Iodine deficiency persists in the former Federal Republic of Germany, including West Berlin, where the use of iodized salt is voluntary. In contrast, iodine supplementation of all household salt and of pig and cattle food was mandated in the former German Democratic Republic in 1986. Subsequently, there was a decrease in thyroid size in newborns and a lower recall rate in the screening program for neonatal hypothyroidism.1 However, since the reunification of Berlin in 1990, iodine supplementation is no longer mandated.

After unification and centralization of laboratory facilities, a large difference in the frequency of high blood thyrotropin concentrations (>15 mU per liter) was noted between neonates in West Berlin and those in East Berlin (0.7 percent vs. 0.1 percent), which was probably due to a difference in iodine supply.2 Therefore, we carried out a prospective study of thyroid function and urinary iodine excretion on the fifth day of life in 761 randomly selected newborns from the two parts of the city in 1991 and 1993. There was no history of perinatal iodine contamination in any infant.3 Serum thyrotropin and thyroxine concentrations were measured by sensitive fluoroimmunoassays, and the iodine concentration of a random urine sample was measured according to the Sandel–Kolthoff method. In both 1991 and 1993 urinary iodine concentrations were higher and serum thyrotropin concentrations were lower in the infants born in East Berlin than in those born in West Berlin (Table 1Table 1Urinary Iodine Excretion and Serum Thyrotropin and Thyroxine Concentrations in Neonates from West Berlin and East Berlin in 1991 and 1993.), whereas the serum thyroxine concentrations were similar in the two groups. These results indicate that infants born in West Berlin were more iodine-deficient than those born in East Berlin. It is unlikely that the difference in urinary iodine excretion was due to greater postnatal intake of iodine in the infants born in the eastern parts of the city, and this would be an even less likely explanation for the differences in serum thyrotropin concentrations.

The historically unique situation created by the reunification of Berlin offered the opportunity to study newborn infants with similar genetic and geographic backgrounds, but with substantial differences in terms of the supply of iodine from their mothers. The results demonstrate that, although the problem of iodine deficiency is well known in Germany, the voluntary intake of iodized salt by pregnant women is not sufficient to protect the fetus and newborn from iodine deficiency. National supplementation programs similar to those in the former German Democratic Republic and other countries are more likely than voluntary programs to eradicate iodine deficiency.

A. Grüters, M.D.
K.P. Liesenkötter, M.D
University Children's Hospital Virchow Klinikum, D-14059 Berlin, Germany

H. Willgerodt, M.D.
University Children's Hospital Leipzig, D-04173 Leipzig, Germany

3 References

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   Willgerodt H, Stach B, Keller E. Die Jodversorgung von Neugeborenen und Erwachsenen nach Einführung der Jodprophylaxe in der ehemaligen DDR -- ein Zwischenbericht und Vergleich mit Neugeborenen in Prag/CSFR. Z Klin Med 1991;46:965-968
   

2. 2

   Delange F, Dodion J, Wolter R, et al. Transient hypothyroidism in the newborn infant. J Pediatr 1978;92:974-976
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   Gruters A, l'Allemand D, Heidemann PH, Schurnbrand P. Incidence of iodine contamination in neonatal transient hyperthyrotopinemia. Eur J Pediatr 1983;140:299-301
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Citing Articles (2)

Citing Articles

1. 1

   Michael B Zimmermann. (2007) The impact of iodised salt or iodine supplements on iodine status during pregnancy, lactation and infancy. Public Health Nutrition 10:12A,
   CrossRef

2. 2

   François Delange. (2007) Iodine requirements during pregnancy, lactation and the neonatal period and indicators of optimal iodine nutrition. Public Health Nutrition 10:12A,
   CrossRef