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Indian Pediatr 2014;51: 65-66 |
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Methodological Issues in Iodine Deficiency
Disorders Survey
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This is in reference to the recent article on "Iodine deficiency
disorder in children of Ambala, Haryana" [1]. We thank the authors for
highlighting an important public health issue; we have the following
concerns:
1. Current irrelevance of the district based
iodine deficiency disorders (IDD) survey: The current district
specific IDD guidelines have their historic genesis from the
National Goitre Control Program (NGCP) (1962). The ban on the sale
of non-iodised salt was based on district level goitre prevalence
and was district specific. However, sufficient evidence has been
generated since establishing IDD as ubiquitous in all states and
geographical regions of India [2,3] and a national level ban on sale
of non-iodised salt was implemented in the year 1997. The current
district specific IDD survey guidelines lack any epidemiological
rationale and cannot be collated to generate state level or national
level data as these surveys are done over different time period.
Further these guidelines do not conform to the internationally
acceptable WHO/ UNICEF/ ICCIDD recommendations.
2. Use of spot testing kits (STK) for salt
iodine content estimation: The iodine content of salt in the
present study was estimated using STK. As the reported sensitivity
and specificity of STKs is low [4] the revised guidelines recommend
iodometric titration for estimating iodine content of salt.
3. Details of the method used for urinary
iodine estimation: The authors have reported that they have used
iodometric titration for iodine estimation in urine but the
prescribed method to estimate urinary iodine as per the guidelines
is Sandell-Kolthoff reaction [5].
4. Need to report median
urinary iodine: In addition to reporting the percentage of
individuals above and below a given cut-off value of urinary iodine,
the authors should have also reported the median urinary iodine. The
revised indicators prescribed by WHO/UNICEF/ICCIDD also suggest
inclusion of median urinary iodine [5].
Kapil Yadav and P Giridara Gopal
Centre for Community Medicine
AIIMS, New Delhi 110 029, India.
Email:
[email protected]
References
1. Chaudhary C, Pathak R, Ahluwalia SK, Goel RKD,
Devgan S. Iodine deficiency disorder in children aged 6-12 years of
Ambala, Haryana. Indian Pediatr. 2013;50:587-9.
2. Indian Council of Medical Research (ICMR).
Epidemiological Survey of Endemic Goitre and Endemic Cretinism, An
ICMR Task Force Study; 1989.
3. Pandav CS, Kochupillai N, Karmarkar MG,
Ramachandran K, Gopinath P, Nath LM. Endemic goiter in Delhi. Indian J
Med Res. 1980;72:81-8.
4. Pandav CS, Arora NK, Krishnan A, Sankar R, Pandav
S, Karmarkar MG. Validation of spot-testing kits to determine iodine
content in salt. Bull World Health Organ. 2000;78:975-80.
5. WHO, UNICEF, ICCIDD. Assessment of Iodine
Deficiency Disorders and Monitoring their Elimination, 3rd edn. Geneva:
World Health Organization. 2007.
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Reply |
We thank the authors for raising important methodological
issues related to iodine deficiency disorder (IDD) survey.
We clarify:
1. The sampling methodology for
selection of survey sites by probability proportionale-to-size
(PPS) sampling adopted in the present study are in
accordance with the revised guidelines of National
Iodine Deficiency Disorder Control Program (NIDDCP) [1]
and WHO/UNICEF/ICCIDD [2]. This method has been found to
be suitable for generating state and national level data
[1].
2. For household surveys, qualitative
testing of salt using a rapid test kit has been employed
successfully to determine overall coverage of iodized
salt and to identify geographical gaps in the program.
Another advantage of rapid test kits is that they can be
used in the field to give an immediate result. However,
because rapid test kits do not give a reliable estimate
of iodine content, results must be backed up by
titration [3]. In the present study, the finding that
88% salt samples were adequately iodized has been made
on the basis of iodometric titration only.
3. We estimated urine iodine content
at IDD monitoring laboratory at Karnal, Haryana with
permission from state IDD control Cell. Sandell Kolthoff
reaction was used for estimation of iodine in urine.
Iodometric titration was actually used in 10% of the
total salt samples for quantitative estimation of
iodine. We apologize for the inadvertent error in the
manuscript.
4. Median urinary iodine
concentration was calculated in the present study as
mentioned in the statistical analysis part of the write
up of the article and was found to be 146 µg/L.
Chintu Chaudhary
Email:
[email protected]
References
1. Directorate General of Health Services
(DGHS). Ministry of Health and Family Welfare, Government of
India. Revised Policy Guidelines on National Iodine
Deficiency Disorders Control Programme. New Delhi: DGHS,
Ministry of Health and Family Welfare, Government of India.
2006;(10).
2. WHO, UNICEF, ICCIDD. Assessment of
Iodine Deficiency Disorders and Monitoring Their
Elimination, 3rd edn. Geneva: World Health Organisation.
2007.
3. Pandav CS, Arora NK, Krishnan A, Sankar R, Pandav S,
Karmarkar MG. Validation of spot-testing kits to determine
iodine content in salt. Bull World Health Organ.
2000;78:975-80.
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