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ORIGINAL ARTICLE
Year : 2021  |  Volume : 65  |  Issue : 2  |  Page : 185-189  

Iodine intake among pregnant mothers residing in hilly terrains of two districts of Himachal Pradesh, India


1 Associate Professor, Department of Community Medicine, Dr. Rajendra Prasad Government Medical College, Kangra, Himachal Pradesh, India
2 Professor and Head, Department of Community Medicine, Dr. Rajendra Prasad Government Medical College, Kangra, Himachal Pradesh, India
3 Assistant Professor, Department of Community Medicine, Dr. Rajendra Prasad Government Medical College, Kangra, Himachal Pradesh, India
4 Lecturer (Statistics), Department of Community Medicine, Dr. Rajendra Prasad Government Medical College, Kangra, Himachal Pradesh, India

Date of Submission21-Dec-2020
Date of Decision18-Feb-2021
Date of Acceptance06-May-2021
Date of Web Publication14-Jun-2021

Correspondence Address:
Dinesh Kumar
Department of Community Medicine, Dr. Rajendra Prasad Government Medical College, Tanda, Kangra, Himachal Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijph.IJPH_1407_20

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   Abstract 


Background: Under programmatic settings, routine monitoring and evaluation of household consumption of iodized salt are recommended to track the reach of universal salt iodization strategy. The program needs evaluation in different settings and locations. Objective: The objective of this study was to assess urine-based estimation for recent iodine intake among pregnant women living in hilly terrains of two districts of northern state of India. Methods: A community-based cross-sectional observational study was conducted during September– December 2019 among 202 randomly selected pregnant women in two districts of Himachal Pradesh. With a predesigned schedule, data regarding sociodemographic and behavioral factors and salt consumption were collected by interview. Iodine level of salt was assessed by spot iodine testing kit and urinary iodine concentration (UIC) was measured using ammonium persulfate digestion using spectrophotometer. Results: Women had a mean age of about 26 years, and the period of gestation was of mean 163.7 days. The consumption of iodized salt (>15 ppm) at family level was found to be 83.7%, and the median UIC was 169.0 μg/L. Among assessed, 26.7% had an acceptable level of UIC, whereas 41.1% and 32.2% of women had less (<150 μg/L) and excessive (>250 μg/L) level of UIC, respectively. Conclusion: Recent iodine intake among pregnant women was observed to be adequate, but efforts are to be done to assess the reasons for less and excessive UIC among women.

Keywords: Iodized salt, median urinary iodine, pregnancy, salt iodine level


How to cite this article:
Kumar D, Raina SK, Chauhan R, Kumar P, Sharma S. Iodine intake among pregnant mothers residing in hilly terrains of two districts of Himachal Pradesh, India. Indian J Public Health 2021;65:185-9

How to cite this URL:
Kumar D, Raina SK, Chauhan R, Kumar P, Sharma S. Iodine intake among pregnant mothers residing in hilly terrains of two districts of Himachal Pradesh, India. Indian J Public Health [serial online] 2021 [cited 2021 Jul 30];65:185-9. Available from: https://www.ijph.in/text.asp?2021/65/2/185/318360




   Introduction Top


Iodine is a basic micronutrient for thyroid function with recommended daily intake from 100 to 150 μg/day for human growth and development. Iodine deficiency occurs when iodine intake falls below recommended level and the thyroid gland is no longer able to synthesize sufficient amounts of thyroid hormone. Universal salt iodization (USI) is recommended under National Iodine Deficiency Disorders Control Programme to address the wide spectrum of iodine deficiency disorders (IDDs). As USI strategy, iodine in cooking salt is recommended to be 15 ppm at consumption level.[1],[2]

Iodine requirement increases in pregnancy and its deficiency in prenatal period has adverse birth and neonatal outcomes.[3] Its requirement increases up to 220–250 μg/day during pregnancy period.[4] In general, on an average, 480-μg and 20-μg iodine is excreted in urine and stool in a day, respectively. Apart from assessment of iodine in salt, measurement of iodine in urine is considered to be an effective indicator to assess recent and adequate iodine intake. Inconsistent excretion of iodine in urine warrants assessment of iodine in urine collected over 24-h period. Since collection and storage of urine over a day become a tedious process for participants, so spot urine collection and median urinary iodine concentration (UIC) are usually recommended to measure population-level iodine intake.[5],[6] It is used as a characteristic indicator for nutritional iodine status and used to evaluate population-based iodine supplementation strategies.[7]

Iodine is largely consumed in the form of salt and its absorption depends on concomitant dietary profile. Simultaneous consumption of food items such as cruciferous vegetables hampers the uptake of iodine by thyroid gland. Dietary profile pattern varies geographically depending upon the food availability and culture. Due to impending risk to a large population for iodine deficiency, USI devised a key strategy to reduce IDDs. Efforts to control goiter stemmed from the Kangra Valley of Himachal Pradesh and resulted in formulation of the National Goiter Control Program in the year 1962.[1] Since then, the program has evolved and currently targeting IDDs rather than only goiter. Under programmatic settings, routine monitoring and evaluation of household consumption of iodized salt are recommended to track the reach of USI strategy.

However, the program needs to be evaluated in different geographical locations. The current study was conducted primarily to assess urine-based estimation for recent iodine intake among pregnant women living in hilly terrains of two districts of Himachal Pradesh, a northern state of India.


   Materials and Methods Top


Study design, area, and subjects

A community-based cross-sectional observational study was conducted among currently pregnant women in two districts of Himachal Pradesh (Kangra and Bilaspur) during September to December 2019. Pregnant women of >18 years residing throughout their pregnancy in the villages of the districts were included in the study. Women not willing to participate and nonresidents (visitors) of village were excluded from the study. Women at term with any sign of immediate labor were also excluded from the study, however, none was found during the survey.

Sampling and selection of subjects

Sample size was calculated considering 37.0% insufficient median urinary excretion of iodine among antenatal women based on an earlier study,[8] with 95% confidence interval, 10% precision, and a design effect of 2.0. Finally, adding 10% nonparticipation rate for urinary samples, the calculated sample size comes to be 200.

An equal number of study participants (100) were selected from each of the two districts as follows. In each district, two community health centers (CHCs) were selected randomly, and then from each CHC, one primary health center (PHC) was again randomly selected. In study districts, the number of villages was usually more and scattered with a small population due to hilly terrain. There were about 43 and 30 villages/PHC in district Kangra (villages: 3,906; PHC: 91) and Bilaspur (villages: 1088; PHCs: 37), respectively. Therefore, from each PHC, a total of 30 clusters (villages) were selected using cluster sampling technique using probability proportional to size. A total of 100 pregnant women were to be recruited from each PHC and about 3–4 women from each village (Figure). Women were recruited during home visits by the team after assessment for inclusion and exclusion criteria. A cluster was divided into four equal quarters by an imaginary line, and from each quarter, a household was selected randomly by a bottle spin method. Hence, one pregnant woman from each household was selected from each quarter. In the case of a small village with inadequate households and pregnant women, adjoining village was selected to meet the sample size per cluster.

Data collection – tools/techniques and measurements

Data were collected by the department of community medicine using a team of postgraduates and medical interns using a pretested structured questionnaire. Data were collected for socioeconomic, demographic, consumption of iodized salt, and urinary iodine.

Measurement of salt consumption was done by standard spoons of small, medium, and large with a capacity of 5, 10, and 15 g, respectively. Women were showed the photograph of a standard spoon and asked about the amount of salt per spoon and number of spoons usually used during cooking. Later on, total amount of salt was divided by number of family members in household to calculate salt consumption per person.

On the date of survey, salt was sampled and tested for level of iodine using rapid iodized salt testing (MBI) kit. It contained a starch-based solution that caused a color-based reaction. Salt turned light blue or dark violet relative to iodine content in salt. The cutoff of ≥15 ppm was considered for consumption of adequately iodized salt.

After obtaining informed consent, a questionnaire was administered by the interviewer and a sterile urine container was handed to women. Participants were given wide opening screw-capped double lid bottle for collection of spot random urine. Bottles were prelabeled with unique identifiers and handed over to participants with instructions. They donated urine sample in privacy at household settings. All samples were stored in a refrigerator from the time of sampling to transportation to laboratory. At laboratory, samples were stored at minus 80°C until analysis of UIC. It was assessed using ammonium persulfate digestion using spectrophotometer (ND 2000, Thermo Fisher Scientific, USA).[9] Median UIC of 150–249 μg/l was considered to be acceptable for pregnant women, and value <150 μg/l was considered for insufficient iodine intake by pregnant women.[10] Thyroid examination of participants was carried out by inspection and palpation with anterior and lateral approach, from behind while child sitting on a chair with a slightly flexed neck. Classification of goiter was done according to recommended criteria by the WHO/UNICEF/ICCIDD and done previously in the same study area as Grade 0: not palpable, Grade 1: palpable but not visible, and Grade 2: Palpable and visible.

Data analysis

Data were entered in Microsoft Excel and analyzed using (version: 7.2.3.1, CDC, Atlanta, Georgia, USA).[11],[12] UIC levels were checked for normality and found to be positively skewed, therefore, both mean and median values are reported. As normal distribution was observed after logarithmic transformation with base 10 of UIC level, so log UIC was used to assess statistically significant difference.

Ethical considerations

The study was approved by the Institute Ethics Committee (IEC), Dr. RPGMC (IEC/2019/195, date: 13/08/2019). Written consent in the local language was also taken from all the women after explaining to them the purpose of the study.


   Results Top


A total of 202 pregnant women were surveyed with a mean age of about 26 years and a period of gestation of about 163.7 days. Most (~60.0%) of the women were in their 2nd trimester of pregnancy. Women had a median monthly family income of Rs. 10,000 (mean: Rs. 13,762.3); 28.7% and 23.0% of families had income below the 25th and above the 75th percentile, respectively. Groundwater was reported to be a common (56.4%) source of drinking water. Previous abortions and stillbirths were reported by 16.3% and 2.4% of women, respectively. Only 4 women (1.9%) were having a child with hearing/speech impairment and 4 women (1.9%) had clinical goiter (Grade 1: 3; Grade 2: 1). Women with clinical presence of goiter were different from women having a child with hearing/speech abnormality [Table 1].
Table 1: Baseline characteristics of pregnant women for iodine deficiency disorders survey in districts of Himachal Pradesh 2019 (n=202)

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The consumption of adequately iodized salt (≥15 ppm) at family level was found to be 83.7%, and 82.3% of women could correctly identify the iodized salt. Salt was reported to be stored in a container with a lid by 96.7% of women. Family-level average salt consumption was found to be 9.2 g/person/day. About a quarter (27.5%) of women were consuming salt <5 g/day, and a majority (43.0%) were consuming salt 6–10 g/day. Assessment for UIC was done among women with mean and median values of 229.1 and 169.0 μg/L, respectively. Among assessed, 26.7% had an acceptable level of UIC, whereas 41.1% and 32.2% of women had less (<150 μg/L) and excessive (>250 μg/L) level of UIC, respectively [Table 2].
Table 2: Salt consumption and iodine excretion among pregnant women for iodine deficiency disorder survey in districts of Himachal Pradesh 2019 (n=202)

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   Discussion Top


The current study was carried out to assess the extent of recent iodine intake among pregnant women in rural areas of Himachal Pradesh. Observance of median UIC as 169.0 (mean: 229.1) μg/L mentioned the absence of population level of iodine deficiency. Evidence suggests that iodine deficiency among pregnant women is indicated when the median UIC value is <150 μg/L.[10] In the present study, but 41.1% of women had UIC of <150 μg/L reflecting inadequate recent iodine intake. It is known that median UIC varies with geography, dietary pattern, and study design, i.e. whether the study was clinic or community based? A clinic-based study among 1031 pregnant women conducted in northern India observed a median UIC of 260 μg/L, and only 13.5% of women had UIC of <150 μg/L.[13] In the same geographical area, a community-based survey among 465 randomly selected individuals reflected a median UIC of 227.4 and 249.1 μg/L with prevalence of low UIC (<100 μg/L) as 20.2% and 13.9% among males and females, respectively.[14] Other clinical-based assessments from southern (226 pregnant women) and northern (150 pregnant women) India observed a respective median UIC of 172.0 and 304 μg/L, respectively.[15],[16] Whereas, some clinic-based assessments observed that about 2.0% of women had had UIC values <150 μg/L.[16],[17] Different from clinic-based findings, a community-based study in a Western state observed a median UIC of 127 μg/L among 360 pregnant women, and of which, more than half (56.0%) have a median UIC <150 μg/L.[18]

USI is known as a key and effective strategy to reduce population-level iodine insufficiency. In India, the current study area in the 1950s gave nourishing evidence favoring iodization of salt, and USI in a country is said to be achieved if at least 90.0% of households consume iodized salt.[1],[19] The risk of iodine insufficiency is indicated where coverage of iodized salt falls below 90.0% consistently over 2 years.[12] Point estimate in the current study observed coverage of 83.7% that could indicate suboptimal levels of iodine in thyroid gland of pregnant women. In India, like median UIC, coverage for adequately iodized salt (>15 ppm) observed to be suboptimal to low in major parts country with poor coverage in its rural areas.[13],[20] Despite high coverage for USI, persistence of IDDs is reported in various parts of country due to the reasons largely attributed to effective implementation to ensure its availability.[21]

Like varying patterns for median UIC and consumption of iodized salt, the prevalence of goiter among pregnant women also showed a varying pattern. Evidence from southern India observed goiter prevalence as 13.0% among 1500 surveyed women of reproductive age group.[22] Another community-wide survey conducted in East-Central India observed a goiter prevalence of 0.2% among 1177 pregnant women.[23] In current study, among women, prevalence of 1.9% was observed for goiter and for children with impairment of with hearing/speech. It is to mention that women with goiter and impairment of child were different. A seminal study in the same study area in the year 1956 gave evidence favoring a reduction in prevalence of goiter after salt iodization.[19] However, reviews have suggested that the consistent consumption of iodized salt, iodine-containing food items, and cooking methods along with restricted use of cruciferous food items play an important role to ensure availability of iodine in sufficient amounts.

The study was observed with some limitations affecting the generalizability. First, total sample size was distributed over to two districts; it would be better for each district. It was not carried out due to logistic constraints. Second, collection of spot over 24-h urine sample to assess UIC could underestimate the opinion about recent iodine intake. However, evidence suggests that at group level, spot sample UIC provides a similar estimate to 24-h sample for suboptimal (<100 μg/L) iodine status and provides a reasonable estimate.[24] Moreover, it is opinionated that beyond spot UIC, more precise definitions and measurements of gestational iodine deficiency need to be developed.[25] Second, sample size limits the subgroup analysis to assess the association between consumption of cruciferous vegetables and salt with UIC. Third, being a cross-sectional study limits to calculate risk of iodine insufficiency, a prospective study explains and measures it better. Finally, thyroid function assessment might have given a valid measure for iodine deficiency to understand the effect of consumption of iodized salt and cruciferous food items.

In summary, a lot more needs to be done to strive the efforts to ensure availability of iodized salt at household level. Overall, suboptimal coverage of iodized salt and high prevalence of women with UIC <150 μg/L need attention in study area. Qualitative studies can be done to understand the reasons for cultural preference of locally available salt over iodized salt despite the ban on noniodized salt. Moreover, pregnant women reflect the suboptimal-level consumption of iodized salt at household level, indicating that more programmatic efforts are required to enhance the coverage to ensure USI.


   Conclusion Top


USI needs to be sustained and assessment of median UIC among pregnant women should be routinely carried out to estimate adequacy of iodine in population.

Acknowledgment

The study was funded by the National Health Mission, Himachal Pradesh.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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