The iodine absorption test is a thyroid iodine 131 test. Thyroid patients are advised to wait 4-6 months after the iodine 131 test before preparing for pregnancy in order to prevent any effect on the fetus. The general procedure of the thyroid iodine 131 uptake test is to take a small amount of iodized salt containing the radionuclide iodine, iodine 131, by mouth or by injection, and then the thyroid gland is tested locally for the strength of the iodine 131 radiation. The Thyroid Uptake Iodine 131 Test provides information about the iodine metabolism or iodine loading status of the thyroid gland, and is mainly used to identify thyrotoxicosis and to help diagnose hyperthyroidism and hypothyroidism. Iodine 131 is a radionuclide and is prohibited for pregnant and lactating women. For pregnant women, it is generally required to prepare for pregnancy 4-6 months after the thyroid iodine 131 test. Thyroid patients are advised to consult their doctors about the effect of iodine uptake test on pregnancy preparation.