Serum-Levels of Protein-Bound Iodine and Thyroxine After a Course of Clioquinol

Changes in the normal range of thyroidal radioiodine uptake

“…TCP solution, often used as a gargle, contains 1-1 mg I/ml, and the popular diarrhoea prophylactic, Enterovioform (clioquinol), contains over 100 mg I per tablet. This is frequently taken by travellers and a typical prophylactic course used by members of the public has been shown to have a persistent effect on the PBI and, presumptively,-also on thyroid uptake test results (S6nksen, Ekins, Stevens, Williams, and Nabarro, 1968). Creams, lotions, and ointments (such as Betnovate C) are frequently made up with 3% clioquinol.…”

Raised serum protein-bound iodine after topical clioquinol

“…Although normal PBI levels were regained by our patients within 3 weeks of the cessation of treatment, the work of Thoren (1960), Levin et al (1966), and *Sonksen et al (1968) suggests that this estimation is probably valueless as a test of thyroid function for at least 2 months after oral administration ofclioquinol.…”

“…The patients were using approximately 1-7 and 1 2 g of the ointment respectively daily, thus each day about 35-50 mg of clioquinol was applied to the skin. Sonksen et al (1968) gave 500 mg clioquinol orally daily for 2 weeks to eight healthy subjects and found a mean PBI level at the end of this period of 118 tug/100 ml. The elevation of the PBI may be influenced by the length of treatment as well as the dose and it may be important that our patients had each been applying the drug for over 4 months.…”

“…Dermatologist, Chelmsford Hospitals RAISED serum levels of protein-bound iodine (PBI) in patients with normal thyroid function have been observed on many occasions after oral treatment with 5-chloro-7-iodo-8-hydroxyquinoline (iodochlorhydroxyquinoline, clioquinol, Enterovioform) (Thoren, 1960;Levin, Josephson & Grtnewald, 1966;Sonksen et al, 1968). It is less well appreciated that clioquinol administered topically can be absorbed in sufficient quantities to influence the PBI and the uptake of radio-active iodine by the thyroid gland.…”

Serum protein-bound iodine or total thyroxine.

“…An example of the lack of specificity of the PBI is seen in figure 2 (Sonksen, Ekins, Stevens, Williams, and Nabarro, 1968). It shows the changes in PBI produced by the commonly taken drug clioquinol together with its lack of effect on serum thyroxine measured by the displacement technique.…”