Tadako Kousaka

Subclinical Graves' disease as a cause of subnormal TSH levels in euthyroid subjects.

In order to elucidate causes of subclinical thyrotoxicosis, we reviewed records of thyroid function tests obtained in our hospital between 1990 and 1992, showing normal thyroid hormones and subnormal TSH levels, and analyzed underlying clinical conditions of the patients. Of 186 patients with normal T4 and/or free T4 and normal T3 and/or free T3 but subnormal TSH (<0.1 mU/l) levels in serum, 150 were under treatment with antithyroid drugs for hyperthyroid Graves’ disease or with thyroid hormones for hypothyroidism. Twelve were in remission after treatment for Graves’ disease, and 4 had destructive thyroiditis. Of the remaining 20 patients, 4 had autonomously functioning thyroid nodule (AFTN), 9 had euthyroid ophthalmic Graves’ disease (EOG), and 7 had diffuse goiter without apparent ophthalmopathy (DG). When thyroid stimulating antibodies (TSAb) were measured in the last 3 groups of the patients, they were detected in none with AFTN but in all patients with EOG and DG. These 7 DG patients without ophthalmopathy had a clinical feature showing unstable thyroid functions, changeable to euthyroidism, overt hyperthyroidism and even hypothyroidism during follow-up. In conclusion, TSAb measurement is useful for detection of subclinical Graves’ disease in euthyroid subjects with subnormal TSH levels in serum.

Comparison of serum thyrotrophin concentrations determined by a third generation assay in patients with various types of overt and subclinical thyrotoxicosis.

Recent increases in the sensitivity of methods used to measure TSH, especially third generation assays, have enabled separation of partial from complete pituitary suppression in patients with thyrotoxicosis. We have investigated the use of a sensitive chemiluminescent enzymeimmunoassay in the differential diagnosis of thyrotoxicosis.

Sequential brain imaging as an aid in understanding disease etiology

Sequential cerebral scintiphotography was performed with a gamma scintillation camera and intravenously administered 99m Tc pertechnetate. The results of the serial scans were correlated with the disease etiology as determined by angiography and surgery. Abnormal foci noted in sequential scinti-photographs revealed either a regressive or progressive course of radionuclide uptake. When the differential uptake was determined digitally, it was possible to classify chronologic patterns of nuclide accumulation into four groups. In Group 1, the uptake ratio reached the maximum value immediately or soon after administration of the tracer and then decreased rapidly. Vascular anomalies, angiomas and meningiomas belonged to this group; angiography and 133 Xe or 131 I-MAA scanning data all demonstrated high blood content and blood flow in the lesions. In Group 2, the uptake ratio showed a progressive increase with time. Gliomas of low grade malignancy, cerebral infarctions and abcesses showed this pattern. In Group 4, the uptake ratio did not exceed unity. This type of lesion was rare and was observed in large intracerebral hematomas and cysts. In Groups 2 and 4, the foci proved to be avascular at surgery or by other diagnostic methods. Group 3 included more or less vascular malignant tumors; namely glioblastomas, carcinomas or sarcomas. The uptake ratio showed an initial increase which was followed by a secondary decrease. In addition to the morphological characteristics of the brain scan such as the size, shape, margin, location, density, homogeneity and multiplicity of the radioactive foci, the dynamic analysis of time course of nuclide uptake appears to improve the diagnostic accuracy and provides useful information concerning the nature of the lesion.