Status of thyroid function in Indian adults: two decades after universal salt iodization

The aim was to find impact of two decades of universal salt iodization on the prevalence of goiter, thyroid autoimmunity and thyroid dysfunction in Indian adults.

This was a cross sectional study from Delhi, India. The subject population included 4409 adult members of resident welfare associations of 5 residential colonies, from 18-90 years of age, who participated in general health check-up camps. The subjects underwent a detailed evaluation including history, anthropometry, goiter grading, USG thyroid, thyroid auto-antibodies and thyroid function tests. All these subjects were regularly consuming iodized salt.

Overall, 9.6% of subjects had clinical goiter (13.3% women and 3.3% in men). Prevalence of nodules on palpation was found to be in 1.6% which was lower in men. The nodule prevalence increased to 4.6% in men and 5.6% in women on ultrasonography. Thyroid hypoechogenicity was seen in 30.6% of subjects with severe hypoechogenicity higher in women (5.7% men and 15.5% women). TPO antibody was positive in 13.3% adults and it showed a positive correlation with age, female sex and hypothyroidism. Subclinical hypothyroidism was the commonest abnormality encountered and affected 19.3% subjects (15.9% men; 21.4% women). Thyroid dysfunction showed a rising trend with age in both genders.

Normal UIE and low goiter prevalence, especially in males, suggest success of the universal salt iodization program in the region under review. High prevalence of subclinical hypothyroidism was not correlated with either thyroid autoimmunity or iodine intake, as reflected in urinary iodine excretion.