title: Moderate-to-Severe Iodine Deficiency in the "First 1000 Days" Causes More Thyroid Hypofunction in Infants Than in Pregnant or Lactating Women.
abstract: Background:Iodine deficiency early in the life cycle-the "first 1000 days"-can cause hypothyroidism and irreversibly impair neuromotor development. However, the relative vulnerability among women and infants during this critical period is unclear, making it difficult for country-based programs with limited resources to prioritize their iodine interventions.Objective:Our aim was to determine the prevalence of thyroid hypofunction in women and infants living in an area of moderate-to-severe iodine deficiency.Methods:In a cross-sectional survey in Morocco, we measured urinary iodine concentrations (UICs) and concentrations of thyroid-stimulating hormone (TSH) and total or free thyroxine (TT4 or fT4, respectively) in women of reproductive age (n= 156), pregnant women (n= 245), and lactating women (n= 239) and their young infants (n= 239). We calculated daily iodine intakes and measured iodine concentrations in breast milk and household salt. We compared the incidence of hypothyroidism between the 3 groups of women and with the infants.Results:Women of reproductive age, pregnant women, and lactating women had median (IQR) UICs of 41 (29-63), 32 (17-58), and 35 (19-62) μg/L; and estimated iodine intakes were ∼60%, 22%, and 26% of Recommended Nutrient Intakes (RNIs). The infants' median UIC was 73 (28-157) μg/L, which was greater than for all 3 groups of women (P< 0.001), and their dietary intakes were 27% of the RNI. The prevalence of hypothyroidism was not significantly different between the 4 groups, whereas the prevalence of hypothyroxinemia was higher in infants (40%) than in the 3 groups of women (11-14%) (P< 0.001). The median breast-milk iodine concentration was 42 (26-81) μg/L. Only 6% of salt samples were adequately iodized to a concentration of ≥15 ppm; 54% were inadequately iodized and 40% contained no measurable iodine.Conclusions:In an area of moderate-to-severe iodine deficiency, the prevalence of thyroid hypofunction is ∼4-fold higher in young infants compared with the 3 groups of women, suggesting that, in the "first 1000 days," infants are more vulnerable than their mothers and that programs should prioritize iodine prophylaxis for this group.
authors.affiliation: Laboratory of Human Nutrition, Institute of Food, Nutrition and Health, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland; sara.stinca@hest.ethz.ch michael.zimmermann@hest.ethz.ch.
authors.forename: Sara
authors.initials: S
authors.lastname: Stinca
authors.affiliation: Laboratory of Human Nutrition, Institute of Food, Nutrition and Health, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.
authors.forename: Maria
authors.initials: M
authors.lastname: Andersson
authors.affiliation: Laboratory of Human Nutrition, Institute of Food, Nutrition and Health, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Herter-Aeberli
authors.affiliation: Mohammed VI University Hospital, Marrakesh, Morocco; and.|Medical and Pharmaceutical Faculty, University Cady Ayyad, Marrakesh, Morocco.
authors.forename: Laila
authors.initials: L
authors.lastname: Chabaa
authors.affiliation: Laboratory of Human Ecology, Faculty of Sciences Semlalia, and.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Cherkaoui
authors.affiliation: Mohammed VI University Hospital, Marrakesh, Morocco; and.|Medical and Pharmaceutical Faculty, University Cady Ayyad, Marrakesh, Morocco.
authors.forename: Nawal
authors.initials: N
authors.lastname: El Ansari
authors.affiliation: Mohammed VI University Hospital, Marrakesh, Morocco; and.|Medical and Pharmaceutical Faculty, University Cady Ayyad, Marrakesh, Morocco.
authors.forename: Abdelmounaim
authors.initials: A
authors.lastname: Aboussad
authors.affiliation: Laboratory of Human Nutrition, Institute of Food, Nutrition and Health, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.
authors.forename: Sandra
authors.initials: S
authors.lastname: Weibel
authors.affiliation: Laboratory of Human Nutrition, Institute of Food, Nutrition and Health, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland; sara.stinca@hest.ethz.ch michael.zimmermann@hest.ethz.ch.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Zimmermann
mesh_terms: D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007455:Iodine / Q000008:administration & dosage* / Q000737:chemistry / Q000172:deficiency* / Q000652:urine; D007774:Lactation; D008297:Male; D008895:Milk, Human / Q000737:chemistry; D011247:Pregnancy; D012965:Sodium Chloride / Q000737:chemistry; D013959:Thyroid Diseases / Q000209:etiology*; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*
chemical_list: D012965:Sodium Chloride; D013972:Thyrotropin; D007455:Iodine; D013974:Thyroxine
keywords: breast-milk iodine concentration; first 1000 days; hypothyroidism; iodine deficiency; lactating women; pregnant women; thyroid-stimulating hormone; thyroxine; urinary iodine concentration; women of reproductive age