CHANGES IN SERUM PROTEIN-BOUND IODINE, SERUM CHOLESTEROL AND THE RADIOACTIVE IODINE EXCRETION TEST IN THYROTOXICOSIS TREATED WITH RADIOACTIVE IODINE

Abstract

ABSTRACT The changes in serum protein-bound iodine and serum cholesterol and in the radioactive iodine excretion test were studied in 144 cases of thyrotoxicosis (98 cases with toxic nodular goitre, 34 with diffuse toxic goitre and 12 with a »non-palpable« thyroid). It is concluded that changes in PBI and cholesterol are usually well correlated with changes in the clinical condition. Measurement of these indices of thyroid function at specified intervals after treatment will therefore give an adequate picture of the clinical course in most cases. In a few cases, however, some discrepancies were observed, notably hypothyroid parameters with euthyroidism in an intermediate stage before final stabilization of the clinical condition occurred. These cases may represent temporary subclinical hypothyroidism. The excretion of radioactive iodine may be elevated in the early phases after treatment, reflecting the radiation injury to the thyroid. In later phases the excretion may remain low, indicating a small thyroidal iodine pool with a rapid turn-over. Hence, the measurement of excretion of radioactive iodine (or the thyroid uptake) after treatment is not very valuable as a thyroid function test but affords other valuable information on the state of the thyroid gland.