Serum thyroid hormones in two Yugoslav districts with different iodine intake.

Serum thyroid hormones were measured in two areas of Yugoslavia, one with relatively low iodine intake, Zagreb (urinary iodide 111 +/- 36 microgram/g creatinine), and the island of Brac with higher iodine intake (247 +/- 76 microgram/g creatinine). The serum concentration of T4 and T3 in two groups were not different. These data confirm previous findings that iodine intake within accepted normal range, is not a factor in determining serum thyroid hormone levels.