Toshiro Sakurada

Measurement of TSH in human amniotic fluid: diagnosis of fetal thyroid abnormality in utero

Using a highly sensitive immunoradiometric assay kit for human TSH, we measured TSH concentrations in unconcentrated amniotic fluids in normal pregnancies and those complicated for example by maternal hyper‐ and hypothyroidism, and compared them with those in maternal and cord sera. In normal pregnancies the mean concentration of TSH in amniotic fluid samples was 0·129 μU/ml, ranging from 0·065 to 0·278 μU/ml. In patients with premature delivery, the amniotic fluid TSH concentration was higher at 0·218 μU/ml. In four patients with abnormal thyroid function, TSH in amniotic fluid changed in parallel to that in cord serum, and there was a significant positive correlation between the two. No such correlation was observed between the concentrations of TSH in amniotic fluid and maternal serum. These results suggest that TSH in human amniotic fluid reflects fetal rather than maternal thyroid function and that the determination of TSH levels in amniotic fluid is useful in the diagnosis of abnormal thyroid function in fetuses.

THYROID FUNCTION IN PATIENTS WITH MYOTONIC DYSTROPHY

In order to investigate endocrine disturbances in patients with myotonic dystrophy (MD), 12 patients and 20 normal controls were studied. All patients were clinically euthyroid and there were no significant differences between circulating levels (mean±SD) of T4 (114.7±26.8 vs 129.9± 28.3 nmol/l), FT4 (16.6±4.5 vs 18.4±3.8 pmol/l), T3 (1.61±0.29 vs 1.86±0.33 pmol/l), TSH (2.7±1.3 vs 2.4±1.4 mU/l), TBG (26.7±5.5 vs 27.6±4.9 mg/l), T4/T3 (84.3±18.4 vs 82.1±15.3), and FT4/FT3 (0.28±0.05 vs 0.33±0.08). Serum FT3 (4.3±1.4 pmol/l) in patients were significantly lower than those (5.3±0.9 pmol/l) in normal controls (P<0.02). Thyroidal131 I‐uptakes (8.7±4.3%) in patients were significantly lower than those (25.8±7.4%) in controls (P<0.01). The mean maximal TSH responses following TRH stimulation were significantly less in patients with MD (11.4±4.5 vs 17.0±6.2 mU/l; P<0.02). Neither circulating thyroid microsomal nor thyroglobulin antibodies were detectable in the 11 patients tested. Serum thyroglobulin concentrations were within the normal range in all patients but one. In conclusion, it is suggested that normal levels of serum T4, T3, FT4, TSH, TBG, T4/T3 and FT4/FT3, slight but significant decrease of serum FT3, reduced TSH response to TRH and a decrease of thyroidal radioiodine uptake might be due to a slight functional failure of TSH secretion in patients with myotonic dystrophy.

EFFECT OF PREDNISOLONE AND SALICYLATE ON SERUM THYROGLOBULIN LEVEL IN PATIENTS WITH SUBACUTE THYROIDITIS

Twelve patients with subacute thyroiditis were divided into two groups and treated with prednisolone or salicylate. The initially elevated T4, T3, free T4 (FT4), free T3 (FT3) and erythrocyte sedimentation rate (ESR) were reduced during the early phase within about 4 weeks in both groups. The serum levels of thyroglobulin (Tg) were elevated in both groups treated with salicylate and prednisolone (252 ± SD 117 ng/ml and 233 ± SD 157 ng/ml, respectively) at initial examination. The serum level of Tg declined during the early phase with prednisolone treatment, and it reached normal values at the end of the early phase (17 ± SD 15 ng/ml). With salicylate treatment, the decline of levels of Tg was delayed and it was elevated (80 ± SD 34 ng/ml) despite normal levels of thyroid hormones and ESR at the end of early phase. The serum level of Tg at the end of the early phase of prednisolone treated was significantly lower than that of salicylate treatment (P<001). It is suggested that the effect of prednisolone on rapid decrease of Tg may be related to its inhibitory action of intrathyroid hydrolysis.

The Monodeiodination of Thyroxine to 3, 3^|^prime;, 5^|^prime;-Triiodothyronine in the Human Placenta

We investigated the characteristics of the monodeiodination of thyroxine to T3 and rT3 in human placentas which were obtained at normal delivery. The placentas were homogenized in a cold sucrose Tris-HCl buffer, pH 7.5. The microsomal fraction was incubated at 37 degrees C in air for 1 hr with 2 micrograms of T4 in the presence of 50mM DTT. The T3 and rT3 generated in the reaction mixture were extracted into cold ethanol and measured by RIA. Among the usal subcellular fractions of the placental homogenate, microsomes were the most potent in deiodinating T4 to rT3. In microsomes, production of rT3 increased with protein concentration, incubation temperature up to 37 degrees C, incubation time up to 120 min and T4 concentration up to 16 micrograms/tube. The production of rT3 from T4 was lost by prior heating of the microsomal fraction to 56 degrees C for 30 min. The net production rate of T4 to rT3 in the microsomal fraction was 17.9 ng/mg protein/micrograms T4/60 min at pH 7.5. RT3 production from T4 was maximal at pH 7.0. The production of T3 from T4 was negligible in the present system. Degradation of T3 in the placentas was rapid. Although the addition of anti-T3 antibody to the reaction mixture suppressed the degradation of T3, it had no effect on the net production of T3, suggesting that the obtained net T3 production rate had not been influenced by its degradation. Degradation of rT3 was negligible. These results indicate that the human placenta actively deiodinates T4 to rT3 enzymatically. This enzyme system might have some influence on the transplacental passage of the thyroid hormone from the mother to the fetus.

Purified Protein Derivative Reaction and Urinary Immunosuppressive Acidic Protein in Patients With Subacute Thyroiditis

Recently we reported1-2 that in acute phase of subacute thyroiditis (SAT) serum immunosuppressive acidic protein (IAP), a type of α1-acid glycoprotein measured by single radial immunodiffusion method is increased, and peripheral K cell activity measured by the modified plaquemethod of Biberfeld et al. was decreased and negatively correlated with serum IAP. Inhibition rate of K cells from a normal subject by sera of patients with SAT in acute phase was higher than that in recovery phase and those of normal control. Purified IAP inhibited K cell activity of normal subject in a dose-dependent manner. Circulating immune-complex measured by modified solid phase Clq-binding assay was almost normal and had no correlation with serum IAP in SAT. Trypsynization of K cells resulted in no change of K cells in both normal subjects and patients with SAT. From these results, it is conceivable that the K cell function is activated to destroy the affected cells probably by virus in the very early phase of SAT and that the K cell activity in SAT might be suppressed by IAP produced from macrophages as defense mechanism against the endless destruction of affected cells by K cells.

Complement Activities and Circulating Immune Complexes in Sera of Patients With Graves′ Disease and Hashimotofs Thyroiditis

In autoimmune thyroid diseases various immunological abnormalities were observed. Circulating immune complexes (CIC) have been detected in sera from patients with Graves′ disease(GD) and Hashimoto’s thyroiditis (HT). Intrathyroidal deposition of immune complexes was reported in these diseases. But the role of CIC in these diseases is not clear. Deposition of immune complexes induces activation of complement system and leads cells to lysis. In these process serum complements are consumed and its activities are reduced in some autoimmune diseases such as systemic lupus erythematodes and serum sickness. In such diseases serum complement activities were reported to correlate with the activity of the disease. In this report we studied about CIC and serum complement activities in patients with GD and HT to clarify the role of CIC and complement in these diseases.

EFFECT OF CADMIUM ON THYROID HORMONE METABOLISM

Monodeiodination is a major pathway of T4 metabolism in the rat as well as in man. The active thyroid hormone, T3, is produced by outer ring deiodination of T4. Thiol agents such as dithiothreitol (DTT), mercaptoethanol, and reduced gluthathione are potent stimulators of this reaction (1). The sulfhydryl-oxidizing agent, diamide, on the other hand, is a potent inhibitor. Heavy metals bind firmly to free sulfur groups and inhibit activities of a large number of enzymes having functional sulfhydryl groups (2). The inhibitory effect of mercury on the conversion of T4 to T3 in vitro has been reported (1,3). In the present paper we describe the effect of cadmium on the hepatic conversion of T4 to T3 in the rat. Furthermore, we have measured serum thyroid hormone concentrations in subjects living in a cadmium polluted area for a long time.

[Two cases of hypothyroidism due to chronic thyroiditis preceding thyrotoxic Graves' disease].

慢性甲状腺炎による甲状腺機能低下症の治療中にBasedow病を発症した2症例を報告した.症例1は39才,症例2は46才の女性で,両者の血清T4, T3および症例1の131I摂取率は正常であつたが,血清TSHが高値であり,抗サイログロブリン抗体,および抗マイクロゾーム抗体が陽性のため,慢性甲状腺炎に伴うsubclinical hypothyroidismとしてl-thyroxineを投与していた.それぞれ2年半および1年後に, T4およびT3が高値となり, l-thyroxineを中止後も高値を持続した. 131I摂取率も高値となり, T3の投与にても抑制されず,ともにBasedow病を発症したものと思われた.症例2では眼症状も認められた.またこれらの例ではTSHリセプター抗体が陽性であつた.

The relationship between serum IAP and peripheral K cells in patients with subacute thyroiditis

In a previous study, we showed that the percentage of peripheral K cells of patients with subacute thyroiditis (SAT), determined by a plaque-forming cell technique, was significantly lower than that of normal controls, and that ther sera from SAT significantly inhibited the activity of K cells in normal lymphocytes, suggesting that in the sera of SAT there is some factor which inhibits K cell activity. In this study, we investigated the relationship between K cells and the serum immunosuppressive acidic protein (IAP), the sex difference in percentage of K cells, and the absolute count of K cells in patients with SAT. In normal controls, there was a sex difference in the percentage of K cells in total lymphocytes; the percentage was significantly lower in women (mean +/- S.D., 5.0 +/- 2.0%; n = 12; p less than 0.01) than in men (8.4 +/- 2.9%; n = 20). However, there was no sex difference in the absolute count of peripheral K cells. In the acute phase of SAT, the percentages of K cells wee 2.4 +/- 1.8%; 2.4 +/- 1.9% and 2.7 +/- 1.0% in 19 patients, 16 females and 3 males, respectively, which were significantly lower than 6.8 +/- 3.0%, 5.0 +/- 2.0% and 8.4 +/- 2.9% in 25 controls, 12 females and 13 males, respectively. The absolute counts of K cells in the acute phase of SAT were 56 +/- 45/mm3 and 58 +/- 48/mm3 in 13 patients including 11 females, respectively, which were significantly lower than 165 +/- 63/mm3 and 153 +/- 73/mm3 in 12 patients including 5 female controls, respectively. It was observed that serum IAP values in SAT were correlated negatively with the percentage of K cells and positively with the inhibition rate of SAT sera on K cells from normal subjects. Moreover, purified IAP showed a dose-related inhibition on the K cells from the control subjects. These results suggest that IAP in the sera of SAT seems to be one of the factors which inhibits the activity of K cells.

[Free thyroxine estimation for screening of hyper- and hypothyroidism in an adult population].

Serum free thyroxine (FT4) was determined in 1,114 adults (male 239, female 875) in a periodic health evaluation in 1980 to detect unsuspected thyroid dysfunction, especially hyper- and hypothyroidism. The participants were dwelling in two towns of Miyagi prefecture. Beside FT4, serum T4 and T3 were also determined by radioimmunoassay. If thyroid dysfunction was suspected, further detailed examinations such as TRH-test (500 micrograms i.v.), radioimmunologic determinations of serum TSH and TBG, resin-sponge T3-uptake, 24-hr thyroid radioiodine 131I-uptake, radioiodine thyroid scan and anti-thyroid antibodies were performed. There were 3 patients with hyperthyroidism (0.27%), 4 with hypothyroidism (0.36%), 3 taking thyroid medication (2; Hashimotos disease, 1; goiter), 3 on estrogen administration, 4 with Hashimotos disease and 1 with goiter. Excluding these 18 patients, FT4, T4 and T3 values in 1,096 euthyroid subjects, 236 males and 860 females, were 1.1 +/- 0.3 (mean +/- S.D.), 1.1 +/- 0.3 and 1.0 +/- 0.3 ng/100 ml, 8.9 +/- 1.5, 8.8 +/- 1.6 and 9.0 +/- 1.5 micrograms/100 ml, and 122 +/- 33, 125 +/- 26 and 122 +/- 35 ng/100 ml, respectively. Serum FT4, T4 and T3 showed the distribution of logarithmic normal probability. The 95% normal range for free T4 was 0.60 to 1.80 ng/100 ml, total T4 6.0 to 11.8 micrograms/100 ml, and T3 84 to 176 ng/100 ml, respectively. Out of 1,114 subjects examined, the cases to be reexamined for the higher serum concentration than normal were 26 in FT4, 35 in T4 and 27 in T3, respectively. And the cases for lower values were 28 in FT4, 31 in T4 and 24 in T3, respectively. Serum FT4 values in the subjects during the administration of estrogens were within the normal range. FT4 and T4 were low in four patients with hypothyroidism, but two of them showed normal T3 values. Determinations of serum FT4, total T4 and total T3 were all useful for the screening of hyperthyroidism. But serum FT4 was the most reliable of the three. Determination of either serum FT4 or total T4 was suitable for the screening of hypothyroidism, but serum total T3 measurement did not cover all patients with hypothyroidism.