Spectrophotometric determination of urinary iodine by the Sandell-Kolthoff reaction subsequent to dry alkaline ashing. Results from the Czech Republic in the period 1994–2002

Abstract

The Czech Republic is an iodine-deficient area. Insufficient iodine intake was reduced by enriching cooking salt with iodine in the range 20-34 mg I/kg. An important indicator for tracking changes in iodine nutrition over time is accurate information about urinary iodine concentrations in the population. In this paper we describe and characterize our method used for the determination of iodine in biological material, which is based on alkaline ashing of urine specimens preceding Sandell-Kolthoff reaction using brucine as a colorimetric marker. The losses of radioiodine added during sample preparation have not exceeded 0.001%. The detection limit is 2.6 microg I/L and the limit of quantification is 11.7 microg I/L, with intra-assay precision of 4% and inter-assay precision of 4.9%. During the period 1994-2002, the urinary iodine concentration was determined in 29,612 samples in the Institute of Endocrinology. The mean basal urinary iodine concentrations+/-SD were 115+/-69 microg I/L. Of the samples, 0.7% were in severe (<20 microg I/L), 9.6% in moderate (20-49 microg I/L), 40.1% in mild (50-99 microg I/L), 35.6% in adequate (100-200 microg I/L), and 14.0% in more than adequate (>200 microg I/L) subsets of iodine nutrition. A statistically significant (p<0.00001) difference was found between mean male (127 microg I/L) and female (112 microg I/L) urinary iodine, and an inversely proportional trend also exists in the age-related data.

ICRP Publication 137: Occupational Intakes of Radionuclides: Part 3

“…Extensive survey data on dietary and urinary iodine (Parr et al., 1992; O’Hare et al., 1998; Iyengar et al., 2004; WHO, 2004; Caldwell et al., 2005; Delange and Dunn, 2005) indicate that iodine intake is at or above recommended levels in much of the world, but is mildly to severely deficient in many regions. Daily intake of iodine is typically 30–40% lower in women than in men (Oddie et al., 1970; Fisher et al., 1971; Milakovic et al., 2004; Bilek et al., 2005; Burman, 2006; CDC, 2008). The following reference values for dietary iodine are selected on the basis of worldwide survey data: 130 µg d −1 for women, 190 µg d −1 for men, and 160 µg d −1 as a sex-averaged value. (203) The following overview of the systemic biokinetic of iodine in adult humans was excerpted from a review by Leggett (2010). (b) Absorption and distribution of inorganic iodide (204) Iodine occurs in foods mainly as inorganic iodide.…”

Hypothyroxinemia during pregnancy: the effect on neurodevelopment in the child

“…Using the Kolthoff–Sandell reaction (Bílek et al, 2005), we determined iodine concentration in a 24‐h urine sample collected from pregnant women at 37 weeks of gestation.…”

A Review of Spectrophotometric and Chromatographic Methods and Sample Preparation Procedures for Determination of Iodine in Miscellaneous Matrices

“…Out of all the samples, 0.7% were in severe (<20 μg/l), 9.6% in moderate (20-49 μg/l), 40.1% in mild (50-99 μg/l), 35.6% in adequate (100-200 μg/l), and 14.0% in more than adequate (>200 μg/l) subsets of iodine nutrition. A statistically significant (p<0.00001) difference was found between the mean male (127 μg/l) and female (112 μg/l) urinary iodine, and an inversely proportional trend also existed in the age-related data (Bílek et al, 2005). It is also known that patients with iodine induced hyperthyrosis have 10-to 100-fold more urinary iodide than healthy patients (Mura et al, 1995).…”