Assessing iodine status and monitoring progress of iodized salt programs

Despite remarkable progress in the control of the iodine deficiency disorders (IDD), they remain a significant global public health problem. Assessing the severity of IDD and monitoring the progress of salt iodization programs are cornerstones of a control strategy. Because thyroid size decreases only gradually in response to iodized salt, the goiter rate in children may be a poor IDD monitoring indicator for several years after the introduction of salt iodization. During this period, the goiter rate reflects chronic iodine deficiency, and will be inconsistent with measurements of urinary iodine. Thyroglobulin is a promising new biochemical indicator for monitoring thyroid function after the introduction of iodized salt. Recent development of a dried blood spot thyroglobulin assay makes sample collection practical even in remote areas. Interpretation of thyroid volume data from ultrasound surveys requires valid references from iodine-sufficient populations, but defining normal values for thyroid size in children has been difficult. New international reference criteria for thyroid volume were published recently and can be used for goiter screening in the context of IDD monitoring. Ensuring sustainability is one of the great remaining challenges in the global fight to eliminate IDD. A recent cohort study demonstrated the vulnerability of children in IDD-affected areas to even short-term lapses in iodized salt programs.