Prevalence of goiter and iodine deficiency ten years after salt iodinezation in school children (8-13 years old) in Marvdasht

Itroduction: Iodine deficiency was endemic in Fars province since several years. Mandatory production of iodinized salt for household use was started from 1994. The aim of this study was to evaluate the prevalence of goiter, urinary iodine excretion in school children ten years after starting the program.

A cross sectional study in which 1188 school children, aged of 8 – 13 years, from Marvdasht city were chosen by random cluster sampling for evaluation of goiter prevalence according to WHO classification. Of these this 1188 school children, 500 persons were selected for evaluation of urinary iodine excretion (UIE) by digestion method, difference in UIE was assessed among different age groups, goitrous and non goitrous school children.

Following the assessment, goiter was found to be still endemic in school children (39.6%) but majority of them had grade1 goiter. Median urinary iodine (95% CI) excretion levels in boys and girls and total number of school children were 17 g/dl (13.1-20.9), 22.4 g/dl (20.4-24.1) and 18.8g/dl (16.1-21.5) respectively. Differences in UIE between two sexes were significant (P < 0.001) but differences among age groups were not significant. The UIE levels in goitrous and non goitrous school children were 18 g/dl (16.4-19.9) and 20 g/dl (17.1-22.9) respectively, with no statistically significant difference. Prevalences of school children with urinary excretion in normal, above normal and below normal ranges were 29.5%, 47.5%, 23% respectively, meanwhile less than 13% had urinary iodine excretion < 5 g/dl.

We conclude that the iodine intake is sufficient but persistent, albeit, reduced prevalence of goiter in spite of adequate iodine supplementation suggests the existence of additional causes in goiterogenesis. It is necessary to consider the role of other factors in persistence of goiter.