A 24-hour thyroid uptake test of sodium iodide I131 performed on 66 euthyroid subjects in Chicago has been analyzed. The new normal range, based on mean ± 2 standard deviations is 7% to 33%, which could explain the discrepancies between patient's clinical status and the results of the uptake test if data previously considered normal (15% to 45%), were applied.
Ghahremani GG, Hoffer PB, Oppenheim BE, Gottschalk A. New Normal Values for Thyroid Uptake of Radioactive Iodine. JAMA. 1971;217(3):337. doi:10.1001/jama.1971.03190030061017