The Effect of Iodized Oil on Goitre Size, Thyroid Function and the Development of the Jod Basedow Phenomenon*

Abstract

SUMMARY In the Lubok Antu district of Sarawak, Malaysia, 240 subjects with 75% prevalence of goitre were studied before and at intervals of 1 and 2 years following iodized oil injection. After 1 year the prevalence of goitre was reduced to 33%, but 2 years after injection, goitres had regrown in fourteen subjects (6%). The mean urinary iodine concentration was low initially at 0±17±0±08 (SD) μmol/l, consistent with iodine deficiency, and rose to a level of 2±6 ± 2±5 μmol/l at 1 year, before falling to 0±46 ± 0±38 μmol/l, again consistent with deficiency. Such a rapid depletion of iodine may be related to the high consumption of cassava. Before injection serum TSH concentrations showed a wide scatter from normal up to 62 mU/l and at 1 year, serum TSH concentrations were undetectable. At 2 years serum TSH was again detectable in 50% of subjects with levels up to 8±6 mu/l. During the 2 years, there was a progressive rise in the mean serum T4 concentration from 92 ± 22 (SD) nmol/l to 110 ± 22 nmol/l (P < 0±05). Serum T3 concentrations rose serially in all subjects from a pre‐injection mean of 1±9 ± 0±3 nmol/l to 2±5 ± 0±9 nmol/l (P < 0±001) and then fell significantly below the baseline level to a mean of 1±7 ± 0±6 nmol/l 2 years after injection (P < 0±01). The mean serum rT3 levels followed the same trend. At 1 or 2 years following injection, eight subjects were clinically hyperthyroid. Four of these consented to venesection and hyperthyroidism was confirmed biochemically. These data reveal that: goitres decreased rapidly in size in response to iodized oil injection; 2 significant though incomplete depletion of the iodine stores occurred within 2 years of injection; the consistent increase in serum T3 was associated with a fall in serum TSH to undetectable levels; the prevalence of the Jod Basedow phenomenon was l±7%. These data suggest the need for closer biochemical monitoring of subjects receiving massive doses of iodine and a reappraisal of the use of iodized oil in the treatment of endemic goitre.

Three-Year Survey of Effects of Iodized Oil Injection in Schoolchildren With Iodine Deficiency Disorders

“…The prevalence and severity of goiter decreased remarkably, so that the prevalence of goiter grade 2 and 3 reduced to one half, 3 years after the intervention. These findings are in accordance with previous reports (Maberly et al, 1982;Lima et al, 1986;Phillips and Osmond, 1989;Lazarus et al, 1992).…”

“…The main strategy to prevent iodine deficiency disorders (IDD) is to provoide, distribute and consume iodized salt (WHO, 1992). However, this mean is not effective in decreasing the size of visible goiters in early phases of the control programs and does not reverse hypothyroidism; therefore, the administration of iodized oil is considered to improve IDD in patients who live in severe iodine deficient regions (Thilly et al, 1973;Maberly et al, 1982;Lima et al, 1986;Phillips and Osmond, 1989), as well as to prevent IDD in fetus, neonates and children (Thilly et al, 1973;Pharoah et al, 1971;Dunn et al, 1986;Pharoah and Connolly, 1987;Fierro-Benitez et al, 1988). In Iran, survey of IDD (Azizi et al, 1990) and administration of universal salt iodization have been implemented during last decade (Azizi, 1995).…”

Long‐term Effect of Iodized Oil on Serum Thyroglobulin Levels in Endemic Goitre Patients

“…In endemic goitre areas a marked decrease in goitre size, an elevation of serum T4 and T3 values, as well as a decrease in the serum TSH concentrations is commonly observed in response to iodized oil (I-oil) injection (Pretell et al, 1969;Thilly et al, 1973;Medeiros-Net0 et al, 1975b;Maberly et al, 1982;Abdel-Wahab et al, 1984). In the present study, in addition of the previously mentioned parameters, we have examined in detail the serum Tg response to TSH in endemic goitre patients before and at 6, 12, 20 and 30 months following the I-oil therapy.…”

Transient Thyrotoxicosis in Endemic Goitre Patients Following Exposure to a Normal Iodine Intake

“…programmes in Europe and South America (Fradkin & Wolff, 1983) and the introduction of iodized bread in Holland and Tasmania (Van Leeuwen, 1954;Connolly et al, 1970;Vidor et al, 1973;Hetzel et al, 1983). Iodine-induced thyrotoxicosis after iodized oil prophylaxis programmes seems to be rare and in one well-documented study (Maberly et al, 1982) was found in 1.7% of the treated population. Spontaneous remission of the thyrotoxic state within a few months without specific treatment is often observed (Nilsson, 1973).…”