HOW SERIOUS IS IODINE DEFICIENCY IN EUROPE ?
Francois Delange, MD, PhD
Past Executive Director and Past Regional Coordinator for Europe of the International Council for Control of Iodine Deficiency Disorders (ICCIDD)
|| printed version
The disorders induced by iodine deficiency (Iodine Deficiency Disorders,
IDD) belong to the history of Europe as all countries, including the Scandinavian
countries with the exception of Iceland, have been exposed in the past to
this medical and socioeconomic scourge. And yet, only limited attention
has been paid to IDD in Europe, probably because of the impact of the outstanding
efficient program of salt iodization in Switzerland (1) and also perhaps
because legislations on iodized salt became available in many additional
countries. The exhaustive review on IDD in the world, including in Europe,
published in 1960 by WHO (2) was followed in the late 1980’s by a
report by the European Thyroid Association which clearly indicated that,
with the exception of the Scandinavian countries, Austria and Switzerland,
most of the European countries or at least certain areas of these countries
were still affected, especially in the Southern part of the continent (3).
A next crucial evaluation of IDD in Europe took place during the international
workshop entitled « Iodine deficiency in Europe : a continuing concern
» held in Brussels in 1992 (4), during which one representative from
each European country summarized the latest IDD data from his country, including
the preventive measures.
In 1997, a follow-up meeting entitled « Elimination of Iodine Deficiency
Disorders (IDD) in Central and Eastern Europe, the Commonwealth of Independent
States and the Baltic States » was organized in Munich (5). This meeting
emphasized the severity of the problem in many parts of Eastern Europe,
including recurrence of goiter and occasionally of endemic cretinism in
some countries such as Russia after interruption of former programs of salt
The objective of the present paper is to provide updated information on
the status of iodine nutrition in the European region. This report is based
on an extensive report on the status of iodine nutrition in Western and
Central Europe (6), on the preliminary results of an ETA-ICCIDD Satellite
meeting to the 28th Annual Meeting of the ETA held in Göteborg in October
2002 (7) and on an exhaustive report on the IDD status in the countries
of the Commonwealth of Independent States (CIS) and Central Asia (8).
|1. IDD in Western and Central Europe
review by Delange (6) has been based mostly on the compilation of publications
in peer reviewed journals and occasionally on information kindly provided
as personal communications by prominent personalities in the field of
IDD in the different European countries. This paper also provided updated
information on the regulations governing the use of iodized salt and market
shares of iodized household salt. For this part, the information has been
largely collected by Mr. Bernard Moinier, Secretary of the European Salt
Producers Association, ESPA, and by Professor Hans Bürgi. This review
paper provided essentially clinical data collected during the past 10
years on the prevalence of goiter and on urinary iodine concentrations.
Thus, it evaluated the present status of iodine nutrition. It concluded
that a country could be considered as iodine sufficient if, based on a
national survey, the prevalence of goiter in the country was below 5 %
and the median urinary iodine was within the normal range, i.e. between
100 and 200 µg/L (9). This report was unable to state that iodine
deficiency had been eliminated in a given country as the criteria proposed
by WHO, UNICEF and ICCIDD for reaching this conclusion are more exhaustive,
including a proportion of households using adequately iodized salt above
90 %, a frequency of urine samples with an iodine concentration of 100
µg/L iodine lower than 50% and the fulfilment of at least 8 of 10
programmatic indicators dealing essentially with the administrative and
political aspects of the organization of the programs at country level
Western and Central Europe include 32 countries, plus Andora, San Marino
and Lichtenstein for which no data are available. National surveys on
the status of iodine nutrition have been conducted during the past 10
years in 17 of these 32 countries. The outcome of these surveys in terms
of prevalence of goiter and urinary iodine concentrations are detailed
in the recent review of the region (6). They cannot be reported in details
here. The global outcome of this European review in terms of status of
iodine nutrition is summarized in the Table :
|Table. Status of iodine nutrition in Western and Central Europe
in early 2003, based on urinary iodine concentrations.
|Iodine sufficiency was unquestionably reached in 14 countries and probably
reached in 5 additional countries, namely Greece, Poland, Portugal, Serbia,
and the United Kingdom. Iodine deficiency, varying from mild to severe,
persisted in an additional 12 countries and no data were available from
the last European country, namely Albania, which is most probably affected.
Some countries deserve particular consideration : in Germany, a national
survey of 3065 school-aged children performed in 2000 reported a national
median of 148 µg/L indicating iodine sufficiency. However, iodine
deficiency continues in some areas with median urinary iodine of 88µg/L.
In Poland, the latest published national survey conducted in 1999 showed
a mean urinary iodine of 96 µg/L indicating an almost complete correction
of iodine deficiency which might have been achieved since. However, the
national program could be in danger if the national authorities interrupt
their support to the national program. Iodine sufficiency has been reached
in Serbia but not in Montenegro. Portugal used to be affected in several
areas but is probably almost close to iodine sufficiency. United Kingdom
is often considered as iodine sufficient but recent national data are missing
and at least pockets of iodine deficiency persist, for example in Scotland
(10). National surveys performed in 1999 in Bosnia and Herzegovina showed
a median urinary iodine of 77.6 µg/L while the figure was 127 µg/L
in the Republika Srpska (7).
|Public health consequences.
The state of mild to severe iodine deficiency persisting in many European
countries has important public health consequences on all age groups
but especially during pregnancy, in the neonates and young infants,
with impairment of the intellectual development as the most significant
In adults, the frequency of simple goiter is elevated and the cost of
therapy of thyroid problems resulting from iodine deficiency is enormous.
For example, in Germany, endemic iodine-deficiency goiter causes economic
costs of approximately one billion US$ or Euros per year (11). Elevated
thyroidal uptake due to iodine deficiency aggravates the risk of thyroid
irradiation and the development of thyroid cancer in case of a nuclear
accident. Thyroid function is frequently altered during pregnancy with
a progressive decline in serum free T4 and consequently an elevation
of serum TSH resulting in the development of goiter in about 10 % of
pregnant women. The alterations are still more marked in neonates than
in their mothers and in Europe, as in other parts of the world, the
results of neonatal thyroid screening for a congenital hypothyroidism
can be used as a sensitive tool for monitoring iodine deficiency and
its control. Another consequence of longstanding iodine deficiency in
the adult is the development of hyperthyroidism, especially in the elderly
with multinodular autonomous goiters. The evidence of this side effect
of iodine deficiency has been the main reason why a country such as
Denmark initiated an efficient program of salt iodization while it was
the last European country in which salt iodization was forbidden up
A key issue is that clinically euthyroid schoolchildren born and raised
in moderately iodine deficient regions of Europe exhibit subtile or
even overt neuropsychointellectual deficits when compared to iodine-sufficient
controls living in otherwise identical ethnic, demographic, nutritional
and socioeconomic populations. These deficits are of the same nature,
although less marked, than those found in schoolchildren in areas with
severe iodine deficiency and endemic mental retardation.
As already indicated, the most important and frequent alterations of
thyroid function due to iodine deficiency in Europe occur in neonates
and very young infants with a high frequency of transient hyperTSHemia
and primary hypothyroidism. The hypersensitivity of neonates to the
effects of iodine deficiency is their low iodine content of the thyroid
with an extremely fast turnover rate of intrathyroidal iodine.
Prevention and therapy.
Seventeen of the 32 countries in the region have a legislation on
iodized salt but which is implemented in only 11 of them. The level
of salt iodization recommended varies from 5 to 70 ppm and the figures
for the market share of iodized packed salt sold to the households vary
from 1 % in Portugal to at least 90 % in Austria, Bulgaria, Croatia,
The Czech Republic, Finland, Macedonia and Poland.
|2. IDD in Eastern Europe, Central Asia and the Baltic States
Doctor Gerasimov recently produced an extensive report with
comprehensive bibliography on the IDD status, control program and salt
iodization in 15 countries of Eastern Europe and Central Asia, including
12 countries of the Commonwealth of the Independent States (CIS) and the
three Baltic States (8).
In the past 5 years, significant information has been collected on the
extent of iodine deficiency in the region. National and sub-national IDD
surveys were conducted in Armenia, Azerbaijan, Belarus and Uzbekistan.
The quite impressive outcome of this survey is that, with the exception
of Armenia where iodine deficiency appears as currently under control
with a median urinary iodine above 100 µg/L, but with persisting
goiter prevalence up to 30 %, iodine deficiency persists in all other
countries, varying from mild to severe ; generally mild in the Baltic
countries, especially Estonia and Lithuania up to mostly severe in Tajikistan
where a survey performed in 1999 reported a prevalence of goiter varying
from 33 to 90 %. Russia never had a national IDD survey on its enormous
territory but several regional assessments conducted from 1998 to 2001
concluded that iodine deficiency persists in most of the administrative
regions. An IDD survey performed in Ukraine in 2000 indicated that significant
iodine deficiency was present not only in the Northern area close to the
Tchernobyl nuclear station but also nationwide.
The iodized salt production was extremely limited in almost all countries
in the region until 1997. Since then, significant efforts by the salt
industry, with international support, have made iodized salt now available
in all countries, and production is scaling up. For example, Russia increased
its iodized salt production from 10,000 ton in 1997 to 120,000 ton in
2001. Most countries in the region adopted harmonized levels of salt iodization
at 40 ±15 ppm and shifted from potassium iodide to the more stable
|Discussion and conclusion
This review underlines
major improvement of iodine nutrition in Europe, as compared to the situation
described in details in 1993 for Western and Central Europe and in 1997
for Eastern Europe, Central Asia and the Baltic States.
In Western and Central Europe, the 1993 report (4) indicated that only
5 countries had reached iodine sufficiency, namely Switzerland, Austria,
Norway, Finland and Sweden. The present figure is 14 countries plus 5
additional countries which have almost reached the goal. In 1999, WHO,
UNICEF and ICCIDD reported that 18 countries in Western and Central Europe
were still affected by iodine deficiency (12). But data from the literature
indicate that three additional countries were also affected, namely Denmark,
France and Ireland (6), which makes a total of 21 affected countries in
this part of the continent. This figure has now been decreased to 12 countries
plus Albania for which no firm data are available but where iodine deficiency
is very likely.
In Eastern Europe, the countries have made substantial progress in evaluation
of IDD status and in expanded production, supply and use of iodized salt.
However, the goal of sustainable elimination of IDD has not yet been reached,
especially in Eastern Europe where only Armenia, and to a lesser extend
Turkmenistan, are close to virtual elimination of iodine deficiency (8).
In 1999, Europe was the less efficient region in the world in terms of
access to iodized salt at the household level in iodine deficient countries
(12). In spite of the progress achieved since, further efforts have to
be developed in order to ensure the recommended daily intake of iodine
for all ages in all inhabitants of Europe, i.e. 90 µg/day from 0
to 59 months, 120 µg/day between 6 and 12 years, 100 µg/day
in adolescents and adults and 200 µg/day in pregnant and lactating
women (9). This has to be achieved principally through implementation
of efficient programs of salt iodization without undue concern to the
possible side effects of the increase of iodine intake (13,14).
The main impact of iodine deficiency is on pregnant and lactating women
and young infants due to role of maternal, fetal and neonatal hypothyroxinemia
in the development of brain damage resulting in irreversible mental retardation
(15-17). As a reply to the famous editorial by Peter Laurberg in 1994
(18): « Iodine intake. What are we aiming at ? », the reply
is clearly that the correction aims not only at increased access to properly
iodized salt and normalization of urinary iodine but mostly at the correction
of the thyroid function during the critical period of brain development
and, consequently, at the prevention of brain damage (19). Iodine deficiency
remains the leading cause of potentially preventable mental retardation
in childhood (14).
The iodine nutrition of Western and Central Europe differs in several
ways from that in other parts of the world (7). Most Western European
countries have iodized salt available but in about half its use is only
voluntary. As in the United States and Canada, most dietary salt comes
from processed food, so the amount of salt added at table and cooking
at home is a relatively minor component of salt intake. Therefore, table
salt is a less important source of iodine nutrition than in developing
countries and the iodization of salt for the baker and for the food industry
are particularly important. National responsibility for iodine nutrition
and its prophylaxis is much weaker in most Western European countries
than in Eastern Europe and in developing countries. The laws and practices
relating to iodized salt vary widely among the countries of Western and
Central Europe and additional efforts to educate the government, the citizens
and even the health professionals have to be markedly increased.
In conclusion, more than half of the people in Western and Central Europe
and a large majority of the people in Eastern Europe and Central Asia
still live in conditions of iodine deficiency. In Western Europe, in contrast
to developing countries, governmental programs to deal with iodine nutrition
are weak or non existent. Consequently, much of the responsibility for
optimal iodine nutrition must be shouldered by others, especially thyroidologists,
academic institutions and the salt industry. In Eastern Europe where national
programs are much stronger, additional efforts are needed especially in
the field of quality control in monitoring the programs. In Europe as
a whole, as long as USI (the Universal salt Iodisation efforts launched
in 1992) is not systematically implemented, special attention has to be
devoted to the protection of the two main target groups to the effects
of iodine deficiency, i.e. pregnant and nursing women, neonates and young
infants. If iodine deficient, these age groups should be supplemented
with physiological quantities of iodine for example by including iodine
to the multivitamins prepared for them or by using iodized oil. Moreover,
the iodine content of formula milk should be increased in Europe to the
presently recommended level of 10 µg/dl milk for fullterms and 20
µg/dl for preterms (4).
The elimination of iodine deficiency is within reach and would constitute
an unprecedented public health success in the field of non communicable
diseases. Additional efforts have to be developed in Europe in order to
reach the goal and, in this part of the world, thyroidologists and their
scientific societies should play a leading role in this direction.
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HOW SERIOUS IS IODINE DEFICIENCY IN EUROPE ?
Title: Hot Thyroidology; Abbreviated key title: Hot Thyroidol.; Online ISSN: 2075-2202
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