BACKGROUND Data suggest symptoms of hypothyroidism persist in 5-10% of levothyroxine (L-T4)-treated hypothyroid patients with normal serum thyrotrophin (TSH). The use of L-T4 + liothyronine (L-T3) combination therapy in such patients is controversial. The ETA nominated a task force to review the topic and formulate guidelines in this area. METHODS Task force members developed a list of releva...

CONTEXT Levothyroxine (LT4) monotherapy is the standard of care for hypothyroidism. OBJECTIVE To determine whether LT4 at doses that normalize the serum TSH is associated with normal markers of thyroid status. DESIGN Cross-sectional data from the US National Health and Nutrition Examination Survey (2001-2012) was used to evaluate 52 clinical parameters. LT4 users were compared to healthy co...

We have previously reported that there is a poor correlation between increase in the levels of UDP-glucuronosyltransferases, UGT1A1 and UGT1A6, and decrease in the levels of serum total thyroxine (T4) and free T4 in phenobarbital (PB)-treated rats, although the PB-induced decrease in rats is generally thought to occur through induction of the UDP-glucuronosyltransferase (T4-UDP-GT: UGT1A1 and U...

In the present study the effects of continuous administration of tumor necrosis factor-alpha (TNF-alpha), in a dose not affecting body temperature and food intake, on pituitary-thyroid function of rats were investigated. Male rats, bearing a venous catheter to allow repeated blood sampling, were intraperitoneally equipped with osmotic minipumps that continuously delivered recombinant human TNF-...

OBJECTIVE The aim was to study whether functional impairment of the pituitary, thyroid, testes, and adrenal glands of humans occupationally exposed to mercury (Hg) vapour can be shown as a result of accumulation of Hg in these glands. METHODS Basal concentrations of thyrotrophin (TSH), prolactin, free thyroxine (free T4), free 3,5,3'-triiodothyronine (free T3), antibodies against thyroperoxid...

On the basis of low specificity, poor positive predictive value, and cost, there is at present no basis for routine assessment of thyroid function in acutely hospitalized patients, unless clinical features suggest the possibility of thyroid dysfunction, or a patient's background increases the likelihood of thyroid dysfunction. When used in severely ill patients, estimates of both thyroxine (T4)...

A cell-free system derived from uninfected Escherichia coli previously was shown to synthesize beta-glucosyl transferase in response to T4 DNA. This same in vitro system, when incubated at slightly higher magnesium concentrations, also synthesized enzymatically active lysozyme. The lysozyme activity that appeared was judged to be T4-specific since antibodies prepared against authentic T4-lysozy...

Woodchucks ( n = 12-14/group) with circannual cycles entrained to northern versus southern hemisphere photoperiods were assessed monthly for 16 mo. Changes in serum total triiodothyronine (TT3), free thyroxine (T4), total thyroxine (TT4), and prolactin were determined in a subset of five animals per group. Metabolic hormone results were examined in relation to changes in body weight, food intak...

OBJECTIVE To evaluate the peer-reviewed literature on iodine deficiency and hypothyroxinemia in pregnancy. METHODS We review published studies on isolated hypothyroxinemia in pregnancy, methodology of free thyroxine (T4) assays, impact of iodine deficiency on free T4 levels, and status of ongoing prospective randomized trials of isolated hypothyroxinemia during pregnancy. RESULTS Hypothyrox...