Mild forms of hypothyroidism – subclinical hypothyroidism – have recently been discussed as being a risk factor for the development of overt thyroid dysfunction and for a number of clinical disorders. The diagnosis critically depends on the definition of the upper normal limit of serum TSH as, by definition, free thyroxine serum concentrations are normal. Cut-off levels of 4–5 mU TSH/l have bee...

OBJECTIVE To study the prevalence of increased TSH level and its probable cause in children with Down's syndrome treated at Policlínica Antônio Cândido. METHODS The data were collected using medical records of 169 patients. Of these, 46 patients, whose TSH increased at some time during their follow-up, were re-evaluated. In these patients, TSH, free T4, total T4 and thyroid peroxidase autoant...

A retrospective analysis of data from 73 consecutive patients with toxic multinodular goitre treated with iodine-131 (131I) during a 2-year period was performed to investigate if serum TSH at the time of 131I treatment influences the outcome. The dose of 131I was calculated according to a model compensating for thyroid size estimated by palpation and 24-h 131I uptake. Serum TSH was determined b...

We have studied the effect of two inhibitors of prostaglandin synthesis on the basal and TRH-stimulated plasma TSH levels in the rat. Animals were injected sc daily with indomethacin 3 mg/0.5 ml) or aspirin (16--30 mg/0.5 ml) for 3 days. The plasma T4 and T3 were consistently lower in the indomethacin or aspirin groups than in the controls, while the basal TSH levels did not change. Indomethaci...

The TSH receptor is a G protein-coupled receptor that mediates the effects of TSH in thyroid development, growth, and synthetic function. We report here that a child with features of TSH resistance, including markedly increased serum TSH concentrations and low normal thyroid hormone levels, is a compound heterozygote for two novel mutations in the TSH receptor gene. One allele has a G to A tran...

We previously reported that microinjection of purified Ras protein stimulated DNA synthesis in quiescent Wistar rat thyrocytes and that TSH (TSH)-stimulated DNA synthesis was Ras-dependent. In contrast to these results, microinjection of cellular or oncogenic Ras significantly reduced TSH-stimulated thyroglobulin (Tg) expression, a marker of thyrocyte differentiation. Microinjection of a domina...

Subclinical hypothyroidism (SCH) patients have normal thyroid hormone levels but increased thyroid stimulating hormone (TSH) level in serum. It has been reported that high TSH is related to abnormal skeletal development in mice with hypothyroidism. However, the cellular mechanism is not fully understood. In the present study, we aim to investigate the direct effects of TSH stimulation on chondr...

Leptin signals the status of energy reserves to the brain. Leptin stimulates biosynthesis of TRH in vitro and influences the activity of the hypothalamic-pituitary-thyroid axis in vivo in rodents. Because blood levels of both leptin and TSH display diurnal variation with a distinct nocturnal rise, we sought to determine whether a relationship exists between fluctuations in circulating leptin an...

teashirt (tsh) encodes a Drosophila zinc-finger protein. Misexpression of tsh has been shown to induce ectopic eye formation in the antenna. We report that tsh can suppress eye development. This novel function of tsh is due to the induction of homothorax (hth), a known repressor of eye development, and requires Wingless (WG) signaling. Interestingly, tsh has different functions in the dorsal an...

Members of the inhibitors of differentiation (Id) family of helix-loop-helix (HLH) proteins are known to play important roles in the proliferation and differentiation of many cell types. Thyroid-stimulating hormone (TSH) regulates proliferation and differentiation by activating TSH receptor (TSHR) in thyrocytes. In this study, we found that Id2, one of the Id family proteins, is a major target ...