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Correlation between per cent discharge of thiocyanate test and thyroid functions in patients with Hashimoto's disease
Insights
The thiocyanate test in Hashimoto's disease patients revealed that impaired iodide organification is not the primary cause of hypothyroidism. This finding suggests a disproportionate uptake and organification of iodide contributes to the condition.
Area of Science:
- Endocrinology
- Thyroidology
- Internal Medicine
Background:
- Hashimoto's disease is an autoimmune disorder leading to hypothyroidism.
- Understanding the mechanisms of iodide handling is crucial for managing thyroid dysfunction.
Purpose of the Study:
- To investigate the role of iodide organification in hypothyroidism within Hashimoto's disease patients.
- To assess the correlation between thiocyanate discharge, thyroid hormone levels, and hypothyroidism severity.
Main Methods:
- Administered oral thiocyanate to 18 Hashimoto's disease patients after 131I tracer doses.
- Measured per cent thiocyanate discharge, T4, TSH, RSH (red blood cell specific gravity), and basal metabolic rate (BMR).
- Utilized chi-square test for statistical analysis.
Main Results:
- Higher thiocyanate discharge correlated with lower T4, RSH, BMR, and higher TSH levels.
- Per cent thiocyanate discharge increased with the degree of hypothyroidism.
- No significant correlation was found between per cent discharge and 131I 24-hour uptake, indicating intact iodide concentration.
Conclusions:
- Hypothyroidism in Hashimoto's disease may not stem from a primary defect in iodide organification.
- A disproportion between iodide uptake and organification might lead to increased unbound iodide.
- Iodide concentration mechanisms remain functional even in severe hypothyroidism associated with Hashimoto's disease.
Abstract:
The thiocyanate test was carried out in 18 patients with Hashimoto's disease. Thiocyanate was given orally several hours after the administration of tracer doses of 131I when the thyroid counts seemed to have reached a plateau. The per cent discharge of thiocyanate test was significantly higher in the groups with lower level of T4 (less than 5.5 microgram/100 ml), RSH (less than 25.5%) and BMR (less than +2.5%), and higher levels of TSH (greater than 10.0 muU/ml). A chi-square (chi2) test with Yates correction led to chi2 = 3.56 (1 df) with P = 0.06 (per cent discharge vs T4, RSU, BMR and TSH). Then the per cent thiocyanate discharge was increased with the degree of hypothyroidism in patients with Hashimoto's disease. The correlation between the per cent discharge and 131I 24 h uptake was not significant. It was apparent that the iodide concentration mechanism was present even in the severe hypothyroid stage of Hashimoto's disease. This disproportion between the uptake of iodide and the iodide organification may result in the increase in unbound iodide. It is concluded that the hypothyroidism in Hashimoto's disease may not be caused by a defect in iodide organification, even if it correlated to the degree of hypothyroidism.