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At least 19 recordsLinked to original sources
PubMed1977

No inhibition by Li+ of thyroxine monodeiodination to 3,5,3'-triiodothyronine and 3,3',5'-triiodothyronine (reverse triiodothyronine).

The possibility that lithium affects the conversion of thyroxine to 3,5,3"-triiodothyronine and 3,3',5'-triiodothyronine (reverse triiodothyronine) was studied by measurement of the serum concentractions of these parameters in five patients during the first week of lithium therapy. In three patients there was a decrease in serum thyroxine concentration and a slightly less pronounced decrease in that of serum 3,5,3'-triiodothyronine. In two patients, who also received L-tryptophan or flupentixol, no change was noted in the concentrations of these compounds. There was no increase in serum 3,3',5'-triiodothyronine concentration in any of the patients. No systematic change was found in the serum concentrations of thyrotropin or unsaturated thyroid-hormone binding proteins. The results obtained do not support the contention that lithium should inhibit the monodeiodenation of thyroxine to its active and inactive metabolites.

Adult↗
PubMed1991

[Normal values for free thyroxine, free triiodothyronine, reverse triiodothyronine, thyrotropin, thyroglobulin and thyroxine-binding globulin in umbilical cord blood of healthy mature newborn infants].

The venous cord blood levels of free thyroxine (fT4), free triiodothyronine (fT3), reverse triiodothyronine (rT3), thyrotropin (TSH), thyroglobulin (TG) and thyroxine binding globulin (TBG) were studied in 56 mature and healthy newborns. Newborns with a gestational age less than 37 or more than 42 weeks, a delivery by forceps or cesarian section, a birth-weight less than 2500 g, a pH-value of the cord-artery blood less than 7.15, an Apgar-value after 1 minute less than 7 were excluded from the study. All mothers were non-smokers. The values of fT4 were 18.66 +/- 4.18 pmol/L, of fT3 were 1.59 +/- 0.75 pmol/L, of fT3 were 2152 +/- 666 pg/ml, of TSH were 7.83 +/- 4.49 mU/ml, of TG were 44.61 +/- 23.84 ng/ml, and of TBG were 25.61 +/- 5.42 micrograms/ml. A weak negative correlation was found between the TG-value and the pH-value of the cord-artery blood (r = -0.27, y = 191.55 - 22.82.x, p less than 0.05), and between the fT4 values and the gestational age (r = -0.34, y = 67.53-1.22.x, p = 0.01). The rT3-values were positively correlated to the gestational age (r = 0.29, y = -4571 + 167.x, p less than 0.03).

Female↗
PubMed1981

Serum thyroxine, triiodothyronine, reverse triiodothyronine, thyroid stimulating hormone, thyroxine binding globulin and thyroxine binding pre-albumin concentrations in healthy African adults.

A study of the serum concentrations of the thyroid hormones thyroxine (T4), triiodothyronine (T3) and reverse triiodothyronine (rT3), thyrotropin (TSH) and the thyroid hormone binding proteins (thyroxine binding globulin (TBG), and thyroxine binding pre-albumin (TBPA)) in non-hospitalized adult Nigerian African subjects was conducted. The subjects were divided into three subgroups, male subjects, non-pregnant female subjects and pregnant female subjects to highlight peculiarities of each sub-group. All three subgroups showed elevation of TBG concentration as compared to British subjects. A statistically significant difference was observed in the concentrations of T4, T3, and TBG in the pregnant female subjects compared to the male and the non-pregnant subjects. A statistically significant difference was also observed between the concentrations rT3 in the male and pregnant female subjects compared to the non-pregnant female subjects. No statistically significant difference was observed between the concentrations of TSH, and TBPA, in all three subgroups, although the mean values for TSH were highest in the pregnant female subjects and the mean values for TBPA and albumin were lowest in this same group. The significance of these findings are discussed in relation to the evaluation of thyroid function in the adult African subject.

Adolescent↗
PubMed1979

Effect of ACTH-stimulated glucocorticoid hypersecretion on the serum concentrations of thyroxine-binding globulin, thyroxine, triiodothyronine, reverse triiodothyronine and on the TSH-response to TRH.

The responses of serum concentrations of TSH, thyroxine (T4), triiodothyronine (T3) and of reverse triiodothyronine (rT3) to i. v. administration of 0.4 mg THR were examined prior to (and after) i. m. administration of ACTH (2 mg Synacthen Depot) in 7 euthyroid women using estrogen-containing oral contraceptives and in 8 controls, with the following results: (1) an increase in endogenous glucocorticoid secretion is associated with a depression of the TSH response to TRH; (2) TSH formed in decreased amounts is still capable of stimulating thyroid secretion; (3) the increased serum corticoid levels fail to affect the secretory response of the thyroid to TSH; (4) control of the pituitary-thyroid axis remains normal in the presence of increased serum thyroxine-binding globulin (TBG) levels. In a further series the serum levels of TBG, T4, T3, rT3 and cortisol under the effect of ACTH-induced endogenous glucocorticoid hypersecretion were studied in 6 normal untreated controls, in 6 normal women using oral contraceptives and in 10 untreated hyperthyroid patients. During four days subsequent to treatment the serum TBG levels decreased, maximum decrease being found in the users of oral contraceptives, minimum decrease in the controls. Serum T4 was found to decrease during 2 to 4 days, serum T3 parallel with an increase in serum rT3, for 1 to 2 days, subsequent for ACTH loading. In the euthyroid cases also the serum TSH levels showed a transitory decline. It is concluded that in case of endogenous hyperproduction of glucocorticoids (1) T4 leads to T3 monodeiodination decreases and T4 leads to rT3 conversion increases parallel with the changes in the serum cortisol levels; (2) TBG synthesis is inhibited by endogenous glucocorticoids; (3) the changes in serum TBG levels are accompanied by a decrease in the serum T4 concentrations.

Adrenocorticotropic Hormone↗
PubMed1976

Effect of amiodarone on serum triiodothyronine, reverse triiodothyronine, thyroxin, and thyrotropin. A drug influencing peripheral metabolism of thyroid hormones.

2-n-Butyl-3-(4'-diethylaminoethoxy-3',5'-diiodobenzoyl)-benzofurane (amiodarone), a drug used in arrythmias and angina pectoris, contains 75 mg of organic iodine/200 mg active substance. Four studies were performed to test its effect on thyroid hormone metabolism: (a) nine male subjects were treated with 400 mg of amiodarone for 28 days; (b) five male subjects received, for the same period of time, 150 mg of iodine in the form of Lugol's solution; (c) five subjects received 300 mug L-thyroxine (T4) for 16 days; from the 10th to the 16th day, 400 mg of amiodarone was added; and (d) five euthyroid subjects received 300 mug L-T4 for 16 days. The changes in serum thyroid-stimulating hormone (TSH), serum total T4, 3,5,3'-triiodothyronine (T3), free T3, and 3,5',3'-triiodothyronine (reverse T3, rT3) were measured, and the pituitary reserve in TSH was evaluated by a thyrotropin-releasing hormone (TRH) test. The results show that amiodarone induced a decrease in serum T3 (28+/-5.1 ng/100 ml, mean+/-SEM, P less than 0.0S and 82.7+/-9.3 ng rT3/100 ml, P less than 0.01). The control study with an equal amount of inorganic iodine did not induce these opposite changes but slightly lowered serum rT3, T3, and T4. In the third study, serum rT3 increased as under amiodarone treatment, thereby proving that these changes were peripheral. It is suggested that amiodarone changes thyroid hormone metabolism, possibly by reducing deiodination of T4 to T3 and inducing a preferential production of rT3. Amiodarone also increased the response of TSH to TRH. The maximal increment of serum TSH above base line was 32+/-4.5 muU/ml under treatment and 20+/-3 muU/ml before treatment (P less than 0.01). During this test, the serum T3 increase was more pronounced than during the control period (83+/-13 and 47+/-7.4 ng/100 ml, P less than 0.05).

Adult↗
PubMed1978

Effects of dexamethasone on fetal and maternal thyroxine, triiodothyronine, reverse triiodothyronine, and thyrotropin levels.

The concentrations of T4, T3, rT3, and TSH were measured at term pregnancy in maternal and umbilical plasma and in amniotic fluid of 11 normal patients who received 8-16 mg dexamethasone 3-48 h before elective cesarean section and of 10 control patients who received no dexamethasone. The mean (+/- SE) concentrations of T4 (micrograms per dl) in maternal and umbilical plasma of dexamethasone-treated patients (12.5 +/- 0.9 and 13.0 +/- 0.9) were not significantly different (P less than 0.05) from those of the control patients (13.9 +/- 1.5 and 10.4 +/- 0.6, respectively). The mean (+/- SE) maternal plasma concentrations of T3 and rT3 (nanograms per dl) of dexamethasone-treated patients (204 +/- 6 and 82 +/- 11) were not significantly different (P less than 0.05) from those of the control patients (201 +/- 26 and 72 +/- 6, respectively). However, the mean (+/- SE) concentrations of T3 and rT3 (nanograms per dl) in umbilical plasma of dexamethasone-treated patients (106 +/- 13 and 360 +/- 35) were 3- and 2-fold and significantly higher (P less than 0.05) than those of the control group (39 +/- 6 and 195 +/- 19, respectively). No significant differences (P less than 0.05) were observed between the mean concentrations of TSH (microunits per ml) in maternal and umbilical plasma of dexamethasone-treated patients (2.5 +/- 0.5 and 3.0 +/- 1.0) and those of the control group (2.8 +/- 0.5 and 6.9 +/- 2.7, respectively). Under the conditions studied, no differences in the mean concentrations of amniotic fluid T4, T3, rT3, or TSH were observed between the two groups of patients (P less than 0.05). The increase of T3 and rT3 levels in umbilical plasma after dexamethasone administration indicates alteration in fetal thyroid economy.

Dexamethasone↗
PubMed1979

Propranolol, triiodothyronine, reverse triiodothyronine and thyroid disease.

Propranolol alone was given to sixteen hyperthyroid, and concomitantly with thyroxine therapy to ten hypothyroid patients. Following treatment of the hyperthyroid group for 1-2 weeks there was a significant decrease in serum triiodothyronine (T3) which correlated with the plasma propranolol steady state concentration. The serum reverse T3 (rT3) rose significantly. Weight loss ceased in this group while weight gain occurred in patients who had a marked fall in serum T3. One patient with T3 toxicosis went into remission. The reduction in serum T3 was maintained in six patients receiving propranolol for more than 1 month. In the hypothyroid group the mean serum T3 level achieved with 0.15 mg thyroxine per day was significantly lower than in a control group who did not receive propranolol. In five patients following propranolol withdrawal there was a significant rise in T3, a fall in rT3 and TSH, and weight loss. Propranol may therefore have a clinically significant and direct action on the peripheral conversion of thyroxine to T3 and rT3.

Adolescent↗
PubMed1985

Thyroxine, triiodothyronine, reverse-triiodothyronine, and other physiological characteristics of periparturient cows fed restricted energy.

Eighty-six cows were assigned to two equal groups with group A fed according to National Research Council recommendations for total digestible nutrients for the 8 wk before parturition and group B was fed 21% higher energy in the first 6 wk and 15% higher in the last 2 preparturient wk. Thyroxine in blood serum decreased in both groups 14 days before and on the day of delivery. It was significantly lower in group A. Findings were similar with triiodothyronine. Blood serum concentrations of reverse-triiodothyronine of group A was significantly higher in group A on day 28 and 14 than group B before delivery. Energy intake had little influence on the serum concentrations of other constituents (albumin, total protein, immunoglobulin G, total and free cholesterol, nonesterified fatty acids). Restricted energy intake that does not alter thyrotropin-thyrotropin-releasing hormone secretion results in higher rate of production of reverse-triiodothyronine and in decreased serum concentration of triiodothyronine. Slight changes of energy balance might be indicated readily by reverse-triiodothyronine concentration in blood serum.

Animal Nutritional Physiological Phenomena↗
PubMed1979

Effect of insulin-induced hypoglycemia on the serum concentrations of thyroxine, triiodothyronine and reverse triiodothyronine.

The effect of insulin-induced hypoglycemia on serum thyroid hormone concentrations was studied in nine healthy individuals. Before, during and after the hypoglycemia blood samples were taken for measurement of the concentrations of glucose, thyroxine (T(4)), triiodothyronine (T(3)), reverse triiodothyronine (rT(3)), catecholamines and pituitary hormones.There was no change in the mean serum T(4) level (+/- the standard error of the mean) of 67 +/- 2 mug/l. However, the T(3) concentrations rose from a mean basal level of 1.86 +/- 0.06 mug/l to a mean peak of 2.51 +/- 0.21 mug/l (P < 0.01) at 45 minutes after the insulin injection, and the rT(3) concentrations fell from a mean basal level of 0.184 +/- 0.008 mug/l to a mean nadir of 0.171 +/- 0.022 mug/l (not a significant change). The mean peak epinephrine level was 545 +/- 103 ng/l and it occurred between 30 and 45 minutes after the insulin injection; the mean peak norepinephrine level was 584 +/- 114 ng/l and it occurred between 30 and 90 minutes after the injection. The growth hormone levels reached a mean peak of 26.1 +/- 4.8 mug/l and the plasma cortisol levels rose to 215 +/- 9 mug/l. The mean basal prolactin level was 8.5 +/- 0.9 mug/l; in five subjects there was a rise to a mean peak of 50.6 +/- 14.6 mug/l, whereas in the remaining four no significant increase occurred. No correlation was found between the changes in the serum T(3) concentration and any of the other factors studied.It was concluded that acute hypoglycemia is associated with a rapid increase in the serum T(3) concentration.

Adult↗
PubMed1981

The effect of surgery with carbohydrate infusion on circulating triiodothyronine and reverse triiodothyronine.

The blood levels of thyrotrophin (TSH), thyroxine (T4), triiodothyronine (T3), and reverse triiodothyronine (rT3) were measured in a group of patients undergoing cholecystectomy and receiving 2000 kcal of glucose daily throughout the study. TSH changes suggested a peroperative peak followed by a fall and subsequent rise. T4 showed no significant changes. T3 fell and rT3 rose postoperatively, with a highly significant fall in the T3/rT3 ratio (p less than 0.001). Surgery and carbohydrate deprivation separately result in similar changes. However, the demonstration of the changes after injury despite adequate carbohydrate intake strongly suggests that they are a primary response to surgery and not a secondary response to the normal consequential fall in caloric and carbohydrate intake. The changes could be an appropriate adaptation to the changed metabolic requirements.

Adult↗
PubMed1986

A new prognostic index in surgery and parenteral feeding: the ratio of triiodothyronine to reverse triiodothyronine in serum (T3/rT3 ratio).

Serum concentrations of albumin, triiodothyronine (T3), and reverse triiodothyronine (rT3) were measured in 46 patients on the first day after routine gastrointestinal surgery, and the molar ratio T3/rT3 was calculated. The median value of this ratio, but not of albumin, was significantly lower in 11 who subsequently suffered major septic complications than in the remainder. Measurement of the ratio correctly predicted the outcome of 80% of individuals. The T3/rT3 ratio, midarm muscle circumference (MAMC), triceps skin fold (TSF) and serum concentrations of albumin and transferrin were measured in 23 patients at referral for parenteral feeding. Median values of T3/rT3 ratio, MAMC and transferrin, but not of the other parameters, were significantly lower in nine who died than in survivors. Measurements of the ratio, MAMC and transferrin correctly predicted the outcome of 87%, 78% and 74% of individuals, respectively.

Journal Article↗
PubMed1995

Differences in the thyroxine, triiodothyronine and reverse triiodothyronine contents of fetal pig tissues relative to gestational age.

The concentrations of thyroxine (T4), 3,5,3'-triiodothyronine (T3) and 3,3',5'-triiodothyronine (reverse T3) were measured in the liver, kidney and skeletal muscles of pig fetuses from day 32 to 113 of age. The iodothyronines were found to be present already between days 32 and 39, that is before the onset of fetal thyroid function. In the liver, kidneys and skeletal muscles T4 reached maximal concentrations at midgestation (days 56 and 93). The T3 level increased with gestational age in all tissues examined but, as opposed to T4, its maximal value was reached shortly before birth. The rT3 level was the highest between days 85 and 100 in the liver and kidney; however, in the skeletal muscles it did not change with gestation. The presented profiles of change of T4 and rT3 in the examined tissues did not correspond to the blood hormone pattern already observed in pig, whereas changes in tissue T3 concentrations were similar to those in the serum.

Animals↗
PubMed1980

Reciprocal changes in serum concentrations of triiodothyronine and reverse triiodothyronine between summer and winter in normal adult men.

Serum concentrations of thyroxine (T4), 3, 5, 3'-triiodothyronine (T3), 3,3',5'-triiodothyronine (reverse T3, rT3), thyronine-binding globulin (TBG), thyroid stimulating hormone (TSH) and cortisol in summer and in winter were compared in carefully selected normal adult men (aged 30-49 yr); 107 people from Sapporo (59 in summer and 49 in winter) and 15 hospital workers. A modest but significantly higher serum T3 concentration was recorded in winter than in summer, while T4, TSH, TBG and cortisol levels were similar in both seasons. Serum rT3 concentration in the Sapporo subjects was slightly higher in summer than in winter but difference was not statistically significant. However, a paired analysis of rT3 concentration in the hospital workers had significantly higher levels in summer than in winter, showed a significant rise in the rT3 to T3 ratio in summer compared to winter. These results were not likely to be due to changes in TBG, cortisol and hematocrit values. The present findings and our previous report on a similar TSH response to thyrotropin-releasing hormone in summer and in winter, indicate that the changes in thyroid hormone metabolism rather than in thyroidal secretion would, at least partly, be responsible for the reciprocal alteration in T3 and rT3 concentrations.

Adult↗