Short-term effectiveness of mandatory iodization of table salt, at an elevated iodine concentration, on the iodine and goiter status of schoolchildren with endemic goiter

Background: Goiter rates and iodine deficiency usually show marked improvem ent in efficacy studies of mandatory iodization of salt, but little is know n about the short-term effectiveness of mandatory iodization. Objective: The aim of the study was to evaluate, after 1 y, the effectivene ss of mandatory iodization of salt at an iodine concentration higher than t hat occurring under optional iodization on the goiter rates and iodine stat us of schoolchildren living in an endemically goitrous area. Design: Goiters, measured by palpation, and urinary iodine concentrations o f children in grades 4-7 in 4 schools in a known goitrous area in South Afr ica were assessed before and 1 y after the introduction of mandatory iodiza tion at a higher iodine concentration than occurred with optional iodizatio n. Estimates of the iodine concentration of iodized salt and the proportion of households using iodized salt were also made. Results: Iodine concentration in table salt and household use of iodized sa lt improved within 1 y. Goiter rates, which varied at baseline from 14.3% t o 30.2% in the 4 schools, remained unchanged, with an overall mean (+/-SE) prevalence of 25.6 +/- 2.5% at baseline and of 27.5 +/- 2.7% 1 y later. The distribution of urinary iodine concentrations in the 4 schools improved su bstantially from the baseline deficient range. The overall median urinary i odine concentration increased from 0.17 to 1.47 mu mol/L. Conclusions: Mandatory iodization of salt virtually eradicated iodine defic iency within 1 y in South African schoolchildren, but the goiter rate in th ese children did not decline. Measurement of goiters by palpation may not b e appropriate in short-term evaluations of mandatory iodization programs.