Ventilation studies and the perfusion lung scan.

hypothyroidism is increased dietary iodine is certainly weakened by the observation that radioresistance was not found in carbimazoleor perchlorate-treated patients. As we stated in the article and as Dr. Wiener has emphasized, the only evidence for iodine as a cause of increased hypothyroidism depends on phar macologie doses. In a manner similar to this last statement, the only obvious difference between our patients and earlier reports is a difference in iodine intake. The third of our patients who were not definitely clinically hypothyroid were not asymptomatic. They had mild-to-moderate symptoms compatible with hypothyroidism, T4 levels of less than 4, and even lower levels of FT4I. They usually also had low T3 levels of RIA and high TSHs. The studies that we used for comparison used criteria of low PBIs plus some symptoms. As such, our criteria for hypothyroidism were as rigid as the studies we used for comparison, if not more so. ROBERT L. YOUNG Wilford Hall USAF Medical Center Lackland AFB, Texas