Transcript Iodine deficiency disorders - Homepage — Universiteit Gent

Iodine deficiency disorders
Iodine is an essential component in thyroid
hormone production
Thyroid hormone regulates basic metabolism
:energy consumption, cellular activity, growth
and in particular brain development.
Hypothyroidism: slow, cold, sluggish brain
function, short stature, mental and motor
development delayed or slowed. In extremes
general neurological development delayed.
Hormone
regulation
Hypothamalus
TSHRF
- Somatostatin
Hypofysis
T4
T3
TSH
T3 T4
I pool
Hormones and iodine deficiency
Spectrum of disease
Table 1. The Spectrum of Iodine Deficiency Disorders, IDD.
Fetus Abortions
Stillbirths
Congenital anomalies
Increased perinatal mortality
Endemic cretinism
Neonate Neonatal goiter
Neonatal hypothyroidism
Endemic mental retardation
Increased susceptibility of the thyroid gland
to nuclear radiation
Child and Goiter
adolescent (Subclinical) hypothyroidism
Impaired mental function
Retarded physical development
Increased susceptibility of the thyroid gland
to nuclear radiation
Adult Goiter with its complications
Hypothyroidism
Impaired mental function
Spontaneous hyperthyroidism in the elderly
Iodine-induced hyperthyroidism
Increased susceptibility of the thyroid gland
to nuclear radiation
Adapted from Hetzel (1), Laurberg et al. (52, 171) and Stanbury et al. (158).
Importance of the problem
Prevalence
1 billion persons exposed
200 million persons affected (goitres)
26 million cases of mental problems
6 million cases of cretinism
Goitre
 Increase in size four to five times distal phalanx
of the thumb
 Aesthetic
 Compression
 Related hypothyroidism: is not a compensation
 cancer
Iod Basedow (hyperthyroidism) due to
hyperstimulation, mutation autonomous nodules
Iodine deficiency and the foetus
Brain development fast between 3-5 months
pregnancy and from third trimester till end of
second year
Maternal T4 essential for first 24 weeks
Foetal T4 starts at 24 weeks
30% cord blood is of maternal origin
Iodine and the neonate
Perinatal mortality
Infant mortality
Low birth weight
Brain development needs T4
Iodine deficiency mental retardation, retarded
motor development.
General IQ decrease of 15 Points
Iodine deficiency and adults
Lack of energy
apathy, slow brains
goitre and mechanical complications
Nodular thyroid
hyperthyroidism
Pregnancy and cretinism
Aethiology
Low iodine uptake. Soil dependent
erosion, wash away: deltas
Goitrogens
Manioc: linnamarin thiocyanate
Blocs uptake of Iodine at the thyroid, competitive
inhibition
Traditional preparations
Konzo
Brassica family
polutants
IDD and selenium deficiency
Se part of peripheral type I de-Iodinase (kidney
and liver)
Se deficiency: slower T4 to T3 metabolisation
Se part of Glutathion peroxidase : protector of
H2O2 damage Thyroid damage, disfunction of
thyroid
Cerebral de-iodinase is not Se dependent
Glutathion peroxidase stimulates T4 production
Iodine needs
RECOMMENDED INTAKE
ug/day
0 - 6 months
35
6 - 12 months
1 - 10 years
>= 11 years
pregnancy – lactation
45
60 – 100
100 - 115
125 - 150
8 ug/kg
5 ug/100ml of milk
7 ug/100 kcal
Diagnosis of endemicity
Prevalence of goitre
Dosage of urinary iodine
TSH dosage
Prevalence of cretinism
Prevalence of goitre
Class
Description
0
Absence of goitre
Ia
Detectable goitre only by palpation and invisible, even when the
head is stretched. More voluminous thyroid than usual, the lobes
have a volume that is at least equal to the volume of the last
phalanx of the subject’s thumb.
Ib
Palpable and visible goitre when the head is stretched. Also all the
cases where there is a nodule - even when there is no goitre.
II
Visible goitre when the head is in a normal position.
III
Very big goitre, visible from a distance
IODE DEFICIENCY
SEVERE
MODERATE
MILD
> 50 %
> 10 %
20-49 % 10-19 %
5-9 %
1-5 %
Number of cases of
goitre among the
school children (6-12)
visible goitre
total goitre
Urinary Iodine
Reflects directly intake
Is best to follow up programme response, goitre
takes time to decrease in size
Samples needed are smaller
Technique is simple and not expensive
Samples can be taken easily, cheap, acceptable
and don’t need conservation techniques
Table 5. Epidemiological criteria for assessing iodine nutrition
based on median urinary iodine concentrations in schoolaged children
Median
Iodine intake
Iodine nutrition
urinary
(µg/L)
iodine
< 20
Insufficient
Severe iodine deficiency
20-49
Insufficient
Moderate iodine deficiency
50-99
Insufficient
Mild iodine deficiency
100-199
Adequate
Optimal
200-299
More than adequate Risk of iodine-induced
hyperthyroidism within 5-10 years
following introduction
of iodized salt in susceptible
> 300
Excessive
Risk of adverse health consequences
(iodine-induced hyperthyroidism,
autoimmune thyroid diseases)
From WHO/UNICEF/ICCIDD (2)
Endemic cretinism
Neurological
Severe motor and mental deficit
cerebral palsy
deafness, mutism
euthyroid
Myoedematous
Severe mental deficit
Hypothyroid, destruction of the thyroid
Iodine deficiency combined with goitrogens and Se
deficiency
Control strategies
Supplementation: injections, oral
Fortification
changing food habits
Supplementation
Need to start early in pregnancy
supplement women of child bearing age
Operational difficulties
Injections and hepatitis and HIV
Covers need for about 4 years injections
Oral covers needs for one year
Fortification
Add iodine to a vehicle: salt or water
Additive must be stable, not change the carrier
No by-pass, centralised production
Need for a comprehensive approach
Packaging, evaporation
Access of all the population to the fortified food
Policy and protection of the market
Who pays?
Success story of Iran
Food habits
Very limited approach, food reflects iodine soil
content
Control complications
Need for intensive follow up
Changing consumption patterns in salt
Variations in salt consumption
Transient hyperthyroidism