(A) study of thyroid function test in hashimoto's disease
Hashimoto씨병에서는 임상 소견이나 갑상선의 형태학적 변화와는 잘 연관이 되지 않는 옥소 대사 및 갑상선 홀몬과 갑상선 자극 홀몬의 대사에 이상이 수반되며 이들 사이에는 상호 연관성이 있음이 제시되고 있다.
저자는 이 질환의 옥소 대사 이상을 파악하고 이 질환의 진단에 도움이 되고자 Hashimoto씨병 환자 32예(갑상선 기능 저하군 12예, 정상군 15예, 항진군 5예)를 대상으로 각종 갑상선 기는 검사 (혈청 T^^2 , T^^4 , TSH농도, 갑상선의 방사성 옥소 섭취율, T^^3 -적혈구 섭취율)를 시행하여 다음과 같은 결과를 얻었다.
Hashimoto씨병의 갑상선 기능 상태는 그 시기에 따라 다르므로 갑상선 기능 검사상의 공통된 특징은 없었으며, 갑상선 기능 정상군의 혈청 T^^3 및 T^^4 농도는 대부분이 정상 범위였고, 항진군에서는 양자가 현저히 증가되어 있어 T^^2 /T^^4 비는 두군이 유사한 반면에, 갑상선 기능 저하군에 있어서는 혈청 T^^4 농도는 감소되어 있는데 혈청 T^^2 농도가 비교적 증가되어 있어 T^^3 /T^^4 비는 두군이 유사한 반면에, 갑상선 기능 저하군에 있어서는 혈청 T^^4 농도는 감소되어 있는데 혈청 T^^2 농도가 비교적 증가되어 있어 T^^3 /T^^4 비 의 평균치가 다른 두군에 비해 두배 정도 높았으며, 혈청 TSH농도도 월등히 증가되어 있었다. 또한 갑상선의 방사성 옥소 섭취율 및 T^^3 -적혈구 섭취율은 Hashimoto씨병의 갑상선 기능 상태를 잘 반영시키지 못함을 관찰하였다.
Iodine metabolism in patients with Hashimoto's thyroiditis shows quantitative and qualitative abnormalities which may vary significantly from patient to patient and which do not correlate well with the type of morphologic changes seen in the thyroid glands or with the clinical picture. These abnormalities in iodine metabolism were summarized by Buchanan and co-workers and can be condensed into the following statements about the thyroid gland involved by Hashimoto's thyroiditis:
(1) it may show release of trapped iodine ("iodine escape"), (2) it has a diminished ability to maintain iodine stores, and (3) if the exchangeable iodine pool in the gland is small, it may have a high turnover rate of exchangeable iodine pool in the gland is small, it may have a high turnover rate of exchangeable iodine. Nonhormonal iodine secretion and increased stimulation by thyroid-stimulating hormone (TSH) may be seen, and the thyroid gland is particularly sensitive to administered iodine in Hashimoto's thyroiditis.
Some of the abnormalities which may exist in Hashimoto's thyroiditis, such as increased TSH stimulation and decreased intrathyroidal iodine pool, have also been shown experimentally to influence the serum triiodothyronine (T3/thyroxine (T4) ratio and to lead to an increase in serum T3.
The purpose of this study was to investigate whether significant abnormalities of concentrations of serum T3, T4 and TSH exist in patients with Hashimoto's thyroiditis, whether measurements of this value in serum would contribute to the
understanding of abnormalities in iodine metabolism in Hashimoto's thyroiditis or assist in its diagnosis and whether the thyroid radioactive iodine uptake (RAIU) and T3-RBC uptake tests reflect the functional state of the thyroid gland.
Serum levels of T3, T4 and TSH, 24-h RAIU and T3-RBC uptake were examined in 32 cases (15 euthyroid, 12 hypothyroid, and 5 hyperthyroid) of 86 patients who were diagnosed of Hashimoto's thyroiditis at Severance Hospital during the period from 1965 to 1977.
The following results were obtained;
1. The ratio of male to female was 1:85. The age distribution was dispersed between 10 and 62 years of age and over half of the cases were in 4th (31.4%) and 3rd (24.4%) decade.
2. In the euthyroid patients with Hashimoto's disease (15 cases; 46.9%), serum T3 concentration was 95-260ng/100ml (mean, 183.3ng/100ml), T4 concentration 4.8-15.6㎍ /100ml (mean, 8.3㎍/100ml) and the T3/T4 ratio 0.009-0.054 (mean, 0.025). The 24-h RAIU showed only 4 cases (28.6%) in normal range (15-45%), 1 case (21%) in decreased state and 9 cases (64.3%) in increased state. The T3-RBC uptake test revealed 8 cases (61.5%) in normal range (11-19%), 1 case (7.7%) in decreased state and 4 cases (30.8%) in increased state.
3. In the hypothyroid patients with Hashimoto's disease (12 case; 37.5%), serum T3 concentration was 100-275ng/100ml (mean, 170.5ng/100ml) and T4 concentration 1.6-5.5㎍/100ml (mean, 3.5ug/100ml). The T3/T4 ratio was 0.026-0.108 (mean, 0.051)
which varied widely, and the mean value of the ratio was twice higher than that of any of the other groups. Serum TSH ranged from 13.5 to 316uu/ml (mean, 106.1uu/ml) which was markedly higher than in any of the other groups. The RAIU showed only 1
case (9.1%) in decreased state, 3 cases (23.7%) in normal range and 7 cases (63.6%) in increased. state. The T3-RBC uptake test revealed no case of decreased state, 6 cases (54.5%) in normal range and 5 cases (45.5%) in increased state.
4. In the hyperthyroid patients with Hashimoto's disease (5 cases; 15.6%), serum T3 concentration with 225-494ng/100ml (mean, 373.4ng/100ml) and T4 concentration with 7.2-24.5㎍/100ml (mean, 17.4㎍/100ml) were markedly higher than in any of the other groups. The T3/T4 ratio ranged from 0.011 to 0.053 (mean, 0.026), which was similar to euthyroid group. The RAIU showed 4 cases (80%) in increased state and 1 case (20%) in normal range. The T3-RBC uptake test revealed 4 cases (80%) in increased state and 1 case (20%) in normal range.
In a brief of this study, there was no specific abnormality in the thyroid function tests in Hashimoto's disease because the functional state of the thyroid gland was variable. However, in the hypothyroid patients with the disease, the T3/T4 ratio was significantly higher than in any of the other groups as the result of decreased serum T4 and increased serum T3 concentrations. At the same time, serum TSH concentration was markedly increased. It is also observed that the RAIU and T3-RBC uptake tests seemed to be inadequate in the diagnosis of Hashimoto's disease.