Table 3. Epidemiological criteria for assessing iodine nutrition of a population based on WHO/ICCIDD recommended indicators (45,46) .

Iodine intake	Iodine status	Median UIC (µg/L)	Total goiter rate (%)	Thyroglobulin (ng/mL, DBS)	TSH >5 mU/L whole blood
School-age children (≥6 years)*					Newborns
Insufficient Severity of public health problem	Iodine deficiency Mild iodine deficiency Moderate iodine deficiency Severe iodine deficiency	<100 50-99 20-49 <20	≥5 ≥30 20-29.9 5-19.9	>40	≥3% 3-19.9% 20-39.9% ≥40%
Adequate	Adequate iodine nutrition	100-199	<5	4-40	<3%
Above requirements	More than adequate†	200-299
Excessive	Excessive‡	≥300
Pregnant women**
Insufficient	Iodine deficiency	<150
Adequate	Adequate iodine nutrition	150-249
Above requirements	More than adequate	250-499
Excessive	Excessive‡‡	≥500

^*Applies to adults, but not to pregnant and lactating women.

^**For lactating women and children <2 years of age a median UIC of 100 μg/L can be used to define adequate iodine intake, but no other categories of iodine intake are defined. Although lactating women have the same requirement as pregnant women, the median UIC is lower because iodine is excreted in breast milk.

^†Likely to provide adequate intake for pregnant/lactating women, but may pose a slight risk of more than adequate intake in the overall population.

^‡Risk of adverse health consequences including iodine-induced hyperthyroidism, autoimmune thyroid diseases.

^‡‡The term “excessive” for pregnant women means in excess of the amount required to prevent and control iodine deficiency.

DBS: dried whole blood spots, ICCIDD: International Council for Control of Iodine Deficiency Disorders, TSH: thyroid-stimulating hormone, UIC: urinary iodine concentration, WHO: World Health Organization