A Review on Iodine Determination Methods in Salt and Biological Samples

Abstract

Context: Iodine is an essential micronutrient, particularly because of its role in the structure of the thyroid hormone. Many people live in iodine deficient regions of the world, and hence need dietary iodine supplement. Though, iodine analysis of biological samples, especially urine, is a method for the evaluation of iodine status in consumers. This paper presents a review of the most common methods used to determine iodine levels in salt and biological samples. Evidence Acquisitions: We conducted a literature review of published English articles in various parts of the world using databases from PubMed, World Health Organization between 1934 and 2012. Results: A total of 2030 articles were identified and after eligibility criteria based evaluation, 63 articles were included in this literature review. The titration method is the most commonly used method for quantitative evaluation. The two main methods used to determine iodine levels in urine and milk are as follows: The instrumental method and the colorimetric methods in association with Sandell and Kolthoff reaction. Conclusions: Despite the high risk of bias of many included studies, the results suggested the Sandell and Kolthoff reaction methods to determine iodine in milk and urine, methods are now technically very simple and have been used by many laboratories to measure iodine levels for many years. The titration method remains the reference method to determine iodine concentrations in salt. Other methods should be standardized against the titration method. Dried whole blood spots Triglycerides (TG) and thyroid stimulating hormone (TSH) are sensitive indicators of iodine deficiency.