Factors affecting the determination of the serum protein-bound iodine

The interpretation of the serum protein-bound iodine: A review

“…Diurnal variations in the serum PBI level are often discounted as being clinically unimportant, eg, by Davis (1966). Nevertheless, Margolese and Golub (1957) in a careful study observed daily fluctuations of as much as 1 5 ,ug/100 ml in the serum PBI level of individual subjects.…”

“…Radiographic contrast media are particularly troublesome. Elevations following intravenous pyelography tend to persist for several days or a few weeks, those following cholecystography persist for months up to many years with transplacental contamination in the case of Teridax, and those following bronchography or myelography persist for many years (see reviews by Sisson, 1965;and Davis, 1966). Placental arteriography within 14 days of birth has been reported to cause a raised serum PBI in the neonate for six to eight months (Simila, Rosberg, and Pystynen, 1967).…”

“…It may be assumed that all radiographic contrast media (other than barium sulphate) will cause false raised levels of the serum PBI which may often persist for several months or years. The effects of intravenous aqueous contrast media are usually shortlived (several days to a few weeks), gallbladder contrast media are often of intermediate life (one to three months) whereas those of oily media for bronchography or myelography and some gallbladder contrast media may persist for years (see Sisson 1965;Davis 1966).…”

The Assay of Urinary Thyroid Hormones for Assessing Thyroid Function

“…Second, most assays determine the total amount of thyroid hormone present rather than the relatively minute free fractions, which are thought to be the metabolically active components (Robbins and Rail, 1957;Ingbar and Freinkel, 1963). Thus the results obtained are influenced by factors that affect either the concentration of thyroid hormone binding proteins (TBP) or their binding capacity (Table 1) as well as by changes in thyroid function (Sisson, 1965;Davies, 1966;Acland, 1958Acland, , 1971). It will be apparent, therefore, that there is an urgent need for a relatively simple technique to assess circulating free T-3 levels.…”

Diagnostic Tests of Thyroid Function

“…The usefulness of the PBI is directly related to the dedication and efficiency of the technician responsible for its measurement; the best possible technique, however, cannot solve the problem of circulating iodine contaminants (Davis, 1966). Various techniques exist for this assay, using different methods of protein precipitation, organic destruction or iodine measurement.…”