Correlation between hospitalization ratio of hyperthyroidism vs hypothyroidism and environmental iodine intake:a retrospective study

Objective To explore the correlation between hyperthyroidism vs hypothyroidism hospitalization ratio(HHHR)and environmental iodine intake.Methods Hyperthyroidism and hypothyroidism hospitalization records,data on salt and environmental iodine intake were collected retrospectively among urban residents of Changzhou city during the period of 1991 to 2004.The data were analyzed with descriptive epidemiological method.Results Totally 2 625 hyperthyroidism and 286 hypothyroidism hospitalization cases were investigated.The HHHR was 4.3 before the universal salt iodization(USI) and increased to 10.7 after USI with a peak value of 19.6.The iodine content of salt was less than 5mg/kg before USI and was 27.7 mg/kg after USI.The environmental iodine intake was increased from 71.6μg/d to 209.0μg/d after USI.Conclusion The increase of HHHR is probably related to the increase of environmental iodine intake.HHHR can be used as the reference for the evaluation of environmental iodine intake.