Determination of the iodine status in pregnant women in the Netherlands.
Are current iodine intake recommendations still adequate?

Adequate dietary iodine intake is essential to thyroid hormone synthesis, which
is key for normal growth, development and metabolism. During pregnancy,
maternal iodine needs are increased and iodine deficiency during pregnancy
might lead to pregnancy complications and can affect brain and cognitive
development of the foetus. Despite iodine fortification programs, it has been
shown that iodine intake in the Netherlands is declining, implicating that also
pregnant women are at risk for iodine deficiency. Low median urinary
concentrations of iodine (81-124 ug/L) in pregnant women have been shown in
several other Western European countries (i.e. Belgium, U.K., Sweden, Denmark
and Austria). However, except for a small pilot study in Groningen that
indicated a high prevalence of iodine deficiency during pregnancy (83%), no
data on iodine intake during pregnancy are available in the Netherlands.
Notably, most studies collected spot-urine samples whereas the golden standard
for determination of iodine status is lacking. Therefore, here we propose to
detemine iodine deficiency during pregnancy in a larger Dutch population, using
the golden standard technique of a 24h urine collection combined with serum
thyroglobulin concentrations.

To determine iodine deficiency in pregnant women in the Netherlands.

This is an observational study to detemine the iodine status of pregnant women
in The Netherlands.
To this end, we will measure the 24h median urinary iodine concentration
corrected for urinary volume and creatinin levels in pregnant women, and
compare these values with Thyroglobulin (Tg)-concentrations in serum (as
measure for iodine intake over a longer period of time). To collect thes data,
women will visit the research center for a single blood draw (15ml), collect
urine for 24h at home and fill out a food-intake questionnaire specific for
iodine-rich foods/supplements.

Data collection includes a single blood collection (max 15 ml), which might
cause some discomfort at the needle insert. A small bruise around the site of
insertion might occur, which will disappear within 1-2 days. The 24h urine
collection is not related to any health risk. Collecting all urinary samples
during 24 hours requires some effort and dedication of the participants.
Materials will be provided including a decent shopper/bag for discretely
carrying around of urine containers. Questionnaires on demographics and food
intake specific for iodine-rich food items and are not considered to be
burdensome.