THE METABOLISM OF IODINE IN CEREBROSPINAL FLUID*†

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Abstract
Iodine compounds in cerebrospinal fluid (CSF) were studied in 11 patients who received therapeutic doses of radioiodine, and in 2 patients who received tracer doses of radioactive thyroxine. CSF iodide concentration in 8 patients ranged from 0.9-4.3% of serum values, with an average of 1.3%. Thyroxine was detected in the CSF of all patients in whom organic analyses were performed. The average concentration in 5 patients was 1.1% of serum values. Calculated values for the concentration of protein-bound iodine in CSF ranged from 0.004 [mu]g/100 ml in a patient with myxedema to 0.122 [mu]g/100 ml in a euthyroid subject. In a patient who received intravenous radiothyroxine, the value was 0.067 [mu]g/ 100 ml. The specific alpha-globulin that binds thyroxine in serum seems to be present in CSF in low concentration. Small amounts of triiodothyronine were detected in the CSF of 3 patients. Thyroglobulin discharged from I131 irradiated thyroid tissue was not detected in the CSF of any patients. In the CSF of 4 patients with thyroid carcinoma the presence of a compound (X), which is associated with certain cases of thyroid cancer, was demonstrated. An unidentified substance (Z) was also detected in the CSF of these patients. Its behavior in 3 chromato-graphic systems was unlike that of the commonly observed iodinated amino acids or the metabolites of thyroid hormone.