Abstract: ObjectiveTo observe the relationship between different iodine intake levels and thyroid disease in medical students.MethodsThyroid healthy volunteers whose age was from 18 to 24 years old were recruited and divided into 7 groups randomly,each group was assigned to receive 500,750,1 000,1 250,1 500,1 750,and 2 000 micrograms iodide oral doses/day for four weeks,respectively.Serum concentration of FT4 and sTSH were measured by chemoluminescence assays.ResultsSome subjects occurred subclinical hypothyroidism after supplied with 500μg～2000μg iodide oral doses/day for 2 weeks.Compared with the other groups,subjects with a 500μg/d iodine oral dose had a lower incidence(15.00%)of subclinical hypothyroidism and the incidence was steady along with time of iodine supplement.The incidence slightly decreased in the group with 1 750μg/d iodine oral intake after 4 weeks.Subclinical hypothyroidism incidences of the rest groups represented an ascending trend along with iodine supplement and were in the rang of 28.00%～47.37%.No subclinical hypothyroidism case was detected after 4 weeks in all groups.ConclusionThe dysfunction of thyroid in normal population was mainly subclinical hypothyroidism with an exposure to a high dose of iodine intake(840μg～2 340μg)during a short period.