In order to prevent goiter, one needs to consume 50 to 70 micrograms of iodine per day. Based on twenty- four- hour urinary iodide levels, 15 percent of people in the low- salt group were at risk of goiter compared to 10 percent of the control group— suggesting there’s a 50 percent increased risk for developing goiter when on a low- salt diet (around 1.9 grams of sodium) versus a normal- salt diet.

--- Does it mean that on the basis of the level of iodide in urine that was checked over 24 hours concluded that 15% of people in one group were at higher risk of developing goiter compared to the other group?


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https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3637997 /

Iodine nutritional status is most closely estimated by the amount of iodine excreted in the urine in 24-h. Often 24-h urine samples for UI determination are impractical to obtain, and can be unreliable because of incorrect or incomplete collection.