[Interference factors in the in vivo diagnosis of the thyroid].

Anamnestic iodine contamination and medication with thyroid drugs were registered in 260 patients of a clinical thyroid care unit and 200 patients of a thyroid doctor's office in the southern German endemic goiter region. We found in the university clinic 54% patients with interfering factors, 30% with iodine contamination and 20% with multiple interferences. In the physician's practice there were 18%, nearly all treated with thyroid hormone. The influence of those factors on thyroidal technetium uptake and the resulting restriction on its diagnostic value is discussed.