When healthy adolescents and adult women drink more fluids and produce more urine, their bodies excrete more iodine through urine, even when their diet stays the same.

In adolescent girls, each extra liter of urine produced is linked to a greater amount of iodine being removed from the body compared to adolescent boys, suggesting that kidneys process iodine differently between the sexes.

People who drink more fluids tend to excrete more iodine in their urine, even when their dietary iodine intake from foods like salt, milk, and fish is accounted for. This suggests that how much fluid a person consumes affects how their kidneys remove iodine from the body.

When measuring iodine levels in urine to assess iodine status, the total amount of urine produced in 24 hours can affect the results, because more urine means more iodine is excreted, even if iodine intake hasn't changed.

Drinking large amounts of non-milk beverages like almond or oat milk may reduce iodine levels in the body because these drinks contain very little iodine, and increased urine output removes more iodine than these beverages replace.