1978 Volume 54 Issue 10 Pages 1151-1156
The conversion process of T4 to T3 or reverse T3 presumably involves deiodinase enzyme systems capable of removing iodide molecules at the 5 or 5′ positions. Although there are scant data to indicate whether these metabolites (T3 and r-T3) themselves are capable of undergoing further deiodination reactions, it seems likely on theoretical grounds that their continued exposure to operative deiodinase enzyme systems would result in the formation of other less iodinated metabolites, such as 33′-T2.
The present report describes the development of a simultaneous analysis of thyroid analogues in biological fluids by mass fragmentography using GC-MS. Analysis was carried out on serum and urine from normal subjects. Similarly, analysis was performed on commercially available thyroid preparations. The TMSi derivatives of the compounds were analyzed by the GC-MS system equipped with a 3ft X 3mm column packed with 1% OV-1, and the temperature was programmed from 250 to 330 C at 10 C/min increments. Thyroid fractions thus separated on the column were subjected to detection of 33′-T2 or r-T3. The following results were obtained.
1) DL-35T2 (commercially available preparation) was found to be composed of 7 mass-spectrometrically different fractions which were detected at the Tyrosine zone, MIT zone, DIT zone, decomposed product of 35-T2 zone, 35-T2, post 35-T2 zone (33′-T2) and leading edge of 33′-T2 zone (decomposed product of 33′5-T3), respectively.
2) L-33′5T3 (commercially available preparation) was found to be composed of 6 mass-spectrometrically different fractions which were detected at the Tyrosine zone, MIT zone, DIT zone, 35-T2 zone, 33′5-T3 zone and post 33′5-T3 zone (33′5′-T3 = r-T3), respectively.
3) The ability to simultaneously analyze 33′-T2, r-T3 and other thyroid analogues should be effectively utilized in order to study further their physiology, production and clearance.
