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

Abstract

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.

Epidemiological survey on the relationship between different iodine intakes and the prevalence of hyperthyroidism

“…But the significantly higher prevalence of TAA in subjects with subclinical hyperthyroidism in Huanghua suggests that subclinical hyperthyroidism may relate to thyroid autoimmunity in an area with severe iodine excess. This is in accordance with the results of a study from Japan with recognized excessive iodine intake (21).…”

Thyroid-Stimulating Antibody in a Patient with Euthyroid Graves' Disease.

“…Our patient developed thyrotoxicosis during follow-up as observed in other reports [4,5]. Moreover, compared with a previous portrait (approximately 3 years prior), both eyes were proptotic at the first visit to our hospital.…”

“…However, the changes in TRAb and TSAb activities do not always parallel each other [18], suggesting that there are heterogeneous antibody activities in sera of patients. There are some reports regarding euthyroid Graves' disease in which TSAb is detectable as frequently as in untreated Graves' disease though the positive rate of TRAb is lower [2,[4][5][6]. This indicates that the presence of TSAb does not necessarily lead to hyperthyroidism [6].…”

“…According to studies of long-term follow-up, some develop hyperthyroidism, some develop hypothyroidism and others remain euthyroid. Recently, this disease has been thought to be related to a thyroid-associated autoimmune mechanism [1], and thyroid-stimulating antibody (TSAb) has been considered to be a useful marker for the diagnosis and follow-up of this disease [2][3][4][5][6] . In this report, we describe a patient with ment of Pediatrics, National Iwakuni Hospital, 2-5-1 There was swelling of the left medial rectus muscle but no retro-orbital tumor was detected by magnetic resonance imaging (MRI) (Fig.…”

Hashitoxicosis (or Graves' disease?) with pericardial effusion

“…In fact, positive TSH-R Abs highly suggest Graves' disease in a thyrotoxic patient even if it is subclinical [3,6]. Additionally, there are also case reports in English literature regarding development of pericardial effusion in patients with Graves' disease [7,8].…”