Download Iodine nutrition during pregnancy

H. Delshad M.D
Endocrinologist
Research Institute For Endocrine Sciences
What is Iodine ?
● Iodine is a chemical element
(as are Oxygen,Hydrogen,Iron)
● Iodine is an essential trace element for the
human
● Iodine is an essential part
of the chemical structure of
thyroid hormones
Total quantity present in body is
(15-20 mg) Mostly in thyroid gland
Discovery of Iodine
● Bernard Courtois discovered Iodine in 1811
● Like most other discoveries, the discovery of Iodine
was a fortuitous
accident.
● While most scientists discovered something when
trying to help people
to save their lives, Courtois discovered Iodine when
4
he was trying to
kill people.
TSH
T3
T4
Iodine
Thyroid Hormone Synthesis
Iodine nutrition and thyroid function
• Iodine is an essential component of
thyroid hormone.
• In turn, thyroid hormone is critical
for neurological development both in
utero and in early life.
Thyroid hormone
• Brain Maturation Stimulate:
– Genes for myelin
– Neurotrophins and their receptors
– Cytoskletone components
– Transcription factors
– Matrix proteins
– Adhesion molecules
– Intracellular signaling molecules
– Mitocondrail gens
– Cerebellar gens
Thyroid hormone
• Mediates growth
•
•
•
•
Body growth
Cell differentiation
Bone maturation
Chondrocyte differentiation
• Brown Fat Thermogenesis
• Non shivering thermogenesis to keep desired body
temperature
Importance of iodine in
brain development
• 50,000 brain cells
produced/second
in developing
fetal brain
• 100 billion brain cells in
adult
• One million billion
connections between
these brain cells:
Determine IQ
Importance of iodine in
brain development
●
90 % of human brain development occurs
between 3rd month of pregnancy & 3rd year of life
● Maternal T4 essential for first 24 weeks
● Foetal T4 starts at 24 weeks
Recommended daily intake
of iodine
Preschool children
90 g
Schoolchildren (6-12 y)
120 g
Adult (>12 y)
150 g
Pregnant
women
&
Lactating
250 g
12
Iodine Requirement (g/day)
During pregnancy
Basal
150
40-50 % increased T4 requirements
50-100
Transfer of T4 and I from mother to fetus
50
Increased renal clearance of I
?
250-300
During lactation
Basal
150
0.5-1.1 L milk/day x 150-180 gI/L
225-350
Delange: Int.J. Endocrinol. Metab. 2: 1, 2004
75-200
Physiologic Changes in Thyroid Function During
Pregnancy
• Thyroid binding globulin (TBG) increases due
to reduced hepatic clearance and estrogenic
stimulation of TBG synthesis
• The test results that change in pregnancy are
influenced by changes in TBG concentration
• Plasma iodide levels decrease due to fetal
iodide use and increased maternal clearance > leads to notable increase in gland size in
15% of women (without abnormal TFTs)
The spectrum of IDD
Fetus
Abortions
Stillbirths
Congenital anomalies
Increased perinatal mortality
Neurologic creatinism
Psychomotor defects
Neonate
Neonatal goiter
Neonatal hypothyroidims
Child & adolescent
Goitrous juvenile hypothyroidism
Impaired mental function
Retarded physical development
Adult
Goiter with its complications
Hypothyroidism
Impaired mental function
16
• The adverse effects of iodine deficiency in
populations (decreased IQ, goiter,
hypothyroidism, and hyper-thyroidism) are
easily corrected with salt iodisation.
• Adequate iodine nutrition in the general
population is shown by a median urinary
iodine concentration for school-age children
(aged 6–12 years) of 100–299 μg/L
• Adequate iodine nutrition in pregnant women
is shown by a median urinary iodine
concentration between 150 and 499 μg/L
Iodine nutrition and thyroid function
• Mild –moderate iodine deficiency has reemerged in countries previously believed to
be iodine sufficient.
• Lately, there has been increasing concern that
even mild-to-moderate iodine deficiency has
adverse clinical outcomes.
• Iodine nutrition during pregnancy has become
an important public health concern
Author
Country
pregnant women
( n)
Median UIC µg/L
% UIC < 150 µg/L
( IQR )
Katz PM
2013
Canada
Toronto
142
221
( 142 – 397 )
29.6
Lindorfer H
2015
Austria
Viena
246
87
86.2
Granfors M
2015
Sweden
459
98
( 57 – 148)
100
Fuse Y
2011
Japan
934
219
16.1
Bath SC
2015
UK
230
56.8
98
Bath SC
2014
South East UK
100
85.3
86
Knight BA
2016
South West UK
308
88
( 54.3 – 157.5)
73
Kirkegeard
2016
Denmark
240
Iodine user : 118
( 79 – 196 )
Non-users: 82
( 41 – 122)
Author
Country
pregnant women
( n)
Median UIC µg/L
% UIC < 150 µg/L
( IQR )
Kasap B
2016
Turkey
135
222
( 141 – 397 )
28.1
Ferreiya SM
2014
Brazil
191
137.7
(132.9 – 155.9 )
92
Bilek R
2016
Czech
Republic
532
82
71.2
De Zoysa E
2016
Sri Lanka
425
105
(67 – 153)
98
Konrad I
2015
Latvia
696
69.4
(53.9 – 92.6 )
100
Raverot V
2012
French
Lyon
228
81
( 8 – 832 )
77
Choyy
2016
Korea
344
427.3
-
‫• هدف ‪ :‬بر رس ی وضعيت دريافت يد و عملکرد غده تيروئيد زنان‬
‫باردار کشور‬
‫• روش کار ‪ :‬در طی يک بر رس ی مقطعی ملی تعداد ‪ 1200‬زن باردار در‬
‫تريمستر های مختلف بارداری از ‪ 12‬استان کشور از آبان ماه تا‬
‫بهمن ماه سال ‪ 1392‬وارد مطالعه شدند‬
‫• شاخص ها ‪ :‬ميانه يد ادرار ‪T4, T3RU, FT4I, TSH,‬‬
‫تيروگلوبولين و آنتی تيروئيد پر اکسيداز سرم مورد اندازه گيری‬
‫قرار گرفتند‪.‬‬
Mean ±SD age of the cohort : 27 ± 7.2 years.
Mean ±SD gestational age:20.7 ± 10.0 weeks.
Min.
‫نتايج کلی‬
UIE (µg /L)
) ‫( میانه ید ادرار‬
T4 (µg/dl)
TSH mIU/L
20
4.92
0.01
:
Max. Preliminary
400 Results
23.92
Mean
Median
114
87.3
14.05
11.19 2.20
10.88
1.95
‫میانه ید ادرار کمتر از ‪100‬‬
‫میانه ید ادرار بين ‪ 100‬و ‪150‬‬
‫نتیجه گیری‬
‫نتایج این مطالعه نشان داد که‬
‫عليرغم دریافت ید کافی جامعه ایرانی‬
‫جمعیت قابل توجه ای از زنان باردار‬
‫ایرانی دچار کمبود متوسط ید بوده‬
‫که نیاز به مکمل ید رسانی در این‬
‫زمان دارند‪.‬‬
Conclusion
• Pregnant women living in mild-moderate
iodine deficient areas are at particularly high
risk of being iodine deficient.
Clinical question
Iodine supplementation in pregnancy-
is it time?
How big is the problem?
• 32 countries ( 1/3 of the global population)
still have inadequate iodine intake.
• In Europe:
►21 countries are iodine deficient in
pregnancy
►10 countries are iodine sufficient
►In 23 countries no data are available
What is the evidence for benefit from iodine
supplementation in pregnancy in mild-moderate iodine
deficiency?
• Avon Longitudinal Study of Parents and
Children ( ALSPAC) study in UK
• 1040 mother-child pairs
• mild-to-moderate iodine deficiency
(UIC < 150 µg/l ) in the first trimester of
pregnancy : odds of offspring IQ being in the
lowest quartile
OR = 1.43; 95%CI 1.04-1.98; P=0.03
• Hynes et al. from Australia
Mild iodine deficiency during pregnancy is
associated with reduced educational
outcomes in the offspring: 9-year follow-up of
the gestational iodine cohort. JCEM 2013
• Taylor et al.
Impact of iodine supplementation in mild-tomoderate iodine deficiency: systematic review and
meta-analysis. Eur J Endo. 2014
• These studies imply there are
potentially substantial benefits
from correcting/ preventing
even mild iodine deficiency in
pregnancy.
Summary of relevant national and societal guidelines
Guideline
Guidance
ATA
Australian Department of Health
ETA
US Teratology Society
Endocrine Society
All women who are planning to be pregnant
or are pregnant or breastfeeding should
supplement their diet with a daily oral
American Academy of Pediatrics
Spanish Endocrine Society
World Health Organization
UK Department of Health
British Thyroid Association
supplement of 150
µg of iodine
(Endocrine Society : 150 - 200µg )
Pregnant and lactating women should take a
supplement containing adequate iodine to
achieve a total of 250 µg iodine / day.
No specific guidance on iodine intake
Key message
• It is probable that, in mild-moderate
iodine deficient countries, iodine
supplementation during pregnancy
and lactation may have substantial
obstetric and offspring benefits and
is economically advantageous.