Determination of Protein-Bound Iodine (PBI) in Sera from Patients with Various Thyroid Diseases by Neutron Activation Analysis

• Published in: RADIOISOTOPES Vol. 16; no. 1; pp. 14 - 18
• Main Authors: HAMADA, Satoshi, TORIZUKA, Kanji, HAMAMOTO, Ken, NAKAGAWA, Jun, MORI, Toru, MORITA, Rikushi, NAKAGAWA, Tsuyoshi, KONISHI, Junji, MIYAKE, Tadashi, FUKASE, Masaichi
• Format: Journal Article
• Language: Japanese
• Published: Japan Radioisotope Association 16.01.1967
• ISSN: 0033-8303; 1884-4111
• DOI: 10.3769/radioisotopes.16.14

Activation analysis was performed for measuring protein-bound iodine (FBI) in serum and trace amounts of iodine. The samples of human serum were passed through an ion-exchange column, and to which were added small amounts of 131I for recovery check. Acid digestion was then carried out by adding chromium trioxide and sulfuric acid, and distillation followed after adding phosphorous acid and hydrogen peroxide. The iodine evolved was trapped in potassium hydroxide. An aliquot of the distillate was placed in a polyethylene ampoule, and was irradiated in the pile at a thermal neutron flux of 4×1012n/cm2/sec for either 15 or 30 minutes. The induced 129I with added carriers was oxidized with Laundry beach, reduced with Na2S2O5, and then extracted with carbon tetrachloride after adding sodium nitrite. The carbon tetrachloride layer was washed with dil-H2SO4 and distilled water. Then 128I was reduced to iodide with Na2S2O5, precipitated with silver nitrate, and assayed in a multi-channel pulse height analyzer and a Geiger-Müller counter. This post-irradiation chemistry could be performed in approximately 30 minutes. The gamma ray spectrum and decay curve indicated the absence of' nuclides other than 128I and 131I. FBI was determined on sera obtained from patients with thyroid diseases and normal subjects, and the values obtained were nearly the same as those by the chemical method. The duplicate determinations indicated good reproducibility. By this procedure, we could measure 2.9×10-9g of iodine.