Determination of thyroid hormones in serum by means of a cation exchange resin and chloric acid digestion

Abstract

SUMMARYA simple and specific method for the determination of iodoamino acids (IAA) and hormonal iodine (HI) in serum is presented. 0.5 ml serum is allowed to run through a small column with a cation exchange resin. To isolate IAA, the column is washed with water and eluted with ammonia. To isolate HI, the column is washed with borate buffer, then with water and eluted with ammonia. After removal of the ammonia by heat, the organic iodine compounds are digested with chloric acid. Iodine is assayed by ceric sulphate-arsenious acid calorimetry. Normal values for IAA ranged from 3.6 to 7.2 pg iodine/roe ml serum (mean value 5.10 yg iodine/roe ml), and for HI from 3.0 to 6.0 ,uug iodine/roe ml serum (mean value 4.30 pg iodinejroo ml).

Determination of triiodothyronine concentration in human serum

“…The columns were packed to a height of 8.0 cm, then activated by washing with 15 ml 1 N HCl which caused shrinkage. This was followed by 30 ml of water which caused swelling back to the original height (24). A porous polyethylene disc (Bel-Art Products, Pequannock, N.…”

Kinetic Measurement of T 4 Following Column Chromatography

“…Borate buffer (pH = S.S);Arsenious acid solution (0.06 mol/1) and Ceric ammonium sulfate solution (0.03 mol/1) were prepared as described by Backer et al (3).…”

Diagnostic Tests of Thyroid Function

“…To overcome this, methods were introduced which were thought to be more specific, e.g, butanolextractable iodine (BEl) (Man, et al, 1951;Man and Bondy, 1957) and measurement after column chromatography on anion or cation exchange-resins (Backer, et al, 1967;Pileggi.er al., 1961). Despite some advantage of these tests in the exclusion of inorganic iodide and iodotyrosines, they will probably now be replaced by direct measurement of serum thyroxine (T4).…”