Iodine deficiency disorders (IDD) is a public health
problem in India. Out of 282 districts surveyed, 241 have been found to
be endemic for IDD(1-3). The deficiency of iodine not only leads to
goiter but also to a spectrum of health consequences(4). It is generally
presumed that iodine deficiency does not exist in desert areas. However,
earlier studies conducted in Rajasthan, a desert state, have documented
a Total goiter rate (TGR) of 23%, 14% and 11 % in the districts of
Bikaner (1990), Kota (1987) and Udaipur (1989), respectively(5). A ban
on the sale of uniodised salt for household consumption has been
introduced in the state since 1992. The present study was conducted in
district Bharatpur, Rajasthan with the objective to assess the
prevalence of iodine deficiency disorders in school children (6-12
years) as no data is available on this aspect.
Subjects and Methods
The study was conducted on 6-12 years old school
going children of Bharatpur District, Rajasthan. Keeping in view the
anticipated prevalence of 15%, a confidence interval of 95%, relative
precision of 15% and with a design effect of 3, a total sample size of
2904 children was calculated(6). Thirty schools were selected using PPS
cluster sampling methodology(7). The identified schools were contacted
and children were briefed about the objectives of the study and informed
consent was undertaken. The date and time for the survey was decided as
per the convenience of the school. In each identified school unit
(cluster), 96 children were enrolled for the study. If the sample could
not be covered from one school, the adjoining school was included to
complete the minimum sample size.
The clinical examination of each child was conducted.
The grading of goiter was done according to the criteria recommended by
the joint WHO/UNICEF/ICCIDD Consultation. When in doubt, investigators
recorded the immediate lower grade. Intra and Inter-observer variation
was controlled by repeated training and random examinations of goiter
grades by the first author. The results were recorded in a pre-designed
questionnaire. The sum of grades I and II provided the TGR of the study
population(6).
On-the-spot urine samples were collected in wide
mouthed screw capped plastic bottles from 10% of the enrolled subjects
randomly. A drop of toluene was added in each bottle to inhibit
bacterial growth and to minimize odor. Urinary Iodine Excretion (UIE)
levels were estimated in the urine samples utilizing the standard Wet
Digestion method(8).
Salt was collected from 35% of the school children
included in the study. Every third child was requested to bring about 20
g of salt that was routinely being consumed in his/her respective home.
The children were provided with auto-seal polyethylene pouches to bring
the salt samples. The iodine content of salt was estimated utilizing the
Spot Testing Kit(9).
Results
A total of 3072 schoolchildren were studied
comprising of 1787 (58.2%) males and 1285 (41.8 %) females. Table I
shows the distribution of children according to their various grades of
goiter. 92.8% subjects were normal i.e., had grade 0 goiter, 7.0%
and 0.2% of the children had grade I and grade II goiter, respectively.
The Total Goiter Rate (TGR) i.e., sum of percentages of goiter
grade I and II was found to be 7.2% indicating an existence of public
health problem of mild degree. Iodine nutriture/requirement is not
dependent on gender for children in the age group of 6-12 years(5).
Thus, separate analysis for boys and girls was not done.
Table I– Distribution of Children According to Various Grades
of Goiter (n = 3072)
Goiter
Grade
|
Males
n(%)
|
Females
n(%)
|
Total
n(%)
|
0
|
1640 (91.8)
|
1212 (94.3)
|
2852 (92.8)
|
I
|
142 (7.9)
|
73 (5.7)
|
215 (7.0)
|
II
|
5 (0.3)
|
0 (0.0)
|
5 (0.2)
|
Total
|
1787 (58.3)
|
1285 (41.7)
|
3072 (100.0)
|
Urine samples were collected randomly from 10% of the
study subjects. Of the 450 urine samples, the proportion of children
with <20.0, 20.0-49.9, 50.0-99.9, 100.0 mcg/L and more was 1.1, 1.1, 7.8
and 90%, respectively. The median urinary iodine excretion of the
subjects in the present study was 200 mcg/L. The urinary iodine values
from populations are usually not normally distributed, and therefore the
median value is used rather than the mean. Hence, we did not calculate
the mean and the standard error of UIE levels of children(6).
The salt samples were analyzed using the Spot Testing
Kit. It was found that 44% of the salt samples had nil iodine and 56% of
the samples had iodine.
Discussion
According to WHO/UNICEF/ICCIDD, if more than 5%
school age children (6-12 yrs) are suffering from goiter, the area
should be classified as endemic to iodine deficiency. In the present
study, a total goiter prevalence rate of 7.2% was found, signifying that
Bharatpur district had mild iodine deficiency. Earlier studies conducted
in the state of Rajasthan have documented a TGR of 23%, 14% and 11% in
the districts of Bikaner (1990), Kota (1987) and Udaipur (1989),
respectively(5).
The median UIE levels of the children studied was
found to be 200.0 mcg/L indicating that there was no biochemical
deficiency of iodine. Only 2.2% of the urine samples had UIE levels <50
mcg/L. Results of the present study indicated that the population is
possibly in a transition phase from iodine deficient (as revealed by TGR)
to iodine sufficient (as revealed by median UIE) nutriture, possibly
because of consumption of iodized salt due to ban on sale of non iodized
salt for edible purposes. To eliminate iodine deficiency disorders,
there is a need to monitor iodine content of salt regularly so that the
entire population of the district receives adequately iodized salt.
Acknowledgement
We would like to thank all the Principals and the
School Teachers for the help extended during the study. We are also
thankful to all the paramedical staff members of the schools for their
most valuable support in the implementation of the study. We would also
like to thank all the students for their kind cooperation in the data
collection. We are grateful to Director, AIIMS, for providing the
financial facilities for conducting the survey.
