Goiter assay

Walker JS, Levy G (1989) Induction of experimental thyroid dysfunction in rats with implantable pellets of thyroxine or propylthiouracil. J Pharmacol Meth 21 223-229 Wiberg GS, Carter JR, Stephenson NR (1964) The effects of various goitrogens on the determination of the relative potency of thyroid by the goiter prevention assay. Acta Endocrin 45 370-380... 

A patient complains of nervousness, palpitations, sweating, and weight loss without loss of appetite, and has a goiter. Suspecting a defect in thyroid function, the physician orders a total serum T4. The test is performed by radioimmunoassay. The standard curve for the assay, which measures T4 in 0.1 ml of serum, is shown below. Normal levels of T4 = 4 — 10 pg/dl. In an assay of 0.1 ml of the patient s serum, 15% of the radioactive T4 was bound to the antibody. 

Work-up for goiter includes a thorough history and physical examination thyroid hormone assays, e.g., TSH, T4, triiodothyronine (T3) and an ultrasound or CT scan. 

In populations with even mild iodine deficiency, an increased goiter rate can be seen. Delange et al. (1997) have measured thyroid volume and urinary iodine excretion in 5709 children aged 7—15 years in different sites in 12 European countries. All ultrasound examinations and urinary iodine assays were performed by the same investigators. An inverse relationship was found (Figure 55.3). 

Figure 60.1 Tg-Ab concentrations in sera measured with both a newiy-deveioped radioimmunoprecipitation assay and a com-merciaiiy avaiiabie passive hemaggiutination assay (Weiicome, UK). ( ) Normai subjects (12 out of 60 had Tg-Ab with the new assay) (V) patients after treatment for Graves disease (23 out of 25 had Tg-Ab) (O) pafients after treatment for muitinoduiar toxic goiter or with atoxic multinodular goiter (20 out of 37 had Tg-Ab) (k) patients after treatment of spontaneously developed hypothyroidism (n = 7, all had Tg-Ab) ( ) patients after previously subacute thyroiditis, (n = 3, all had Tg-Ab). Data from Laurberg and Pedersen (1988) with permission.

However, Aese indications for thyroid uptake have virtually disappeared, first because of the replacement of TSH stimulation test by sensitive TSH assays (H4, 18) and, second, by the replacement of tests of thyroid autonomy, such as the Ts suppression tests by TRH stimulation tests (see Section 5.3). This restricts the application of diyroid uptake tests mainly to a few special areas, particularly as a key test in the elucidation of patients with biosynthetic goiter. Many of these patients are children, and it is desirable to use in these as it has been shown that the radiation exposure from the standard dose of is approximately % of the exposure from the equivalait dose of (H18). Another advantage in using is that repeated studies in the one patient are possible, as its half-life is 2.2 hours compared with 8 days for I, and therefore there are no errors from residual activity from a previous dose. 

G. Lanzer and G.J. Krejs, Chromatographically Purified Immunoglobulin G of Endemic and Sporadic Goiter Patients Stimulates FRTL-5 Cell Growth in a Mitotic Arrest Assay, J Clin Endocrinol Metab 79 444 (1990). 

The objectives of the study were to provide the population with a daily supply of 100-150 ig of iodine in drinking water, to verify the absorption of the iodized water by assaying the urinary iodine, and to verify that the iodine reached the thyroid, by monitoring the reduction of goiters. In this one year study we assessed the effect of RHODIFUSE system, its duration of efficacy, and its acceptability by local populations. 

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