scholarly journals Free T3 to free T4 ratio less than 2.0 suggests low T3 syndrome rather than central hypothyroidism from the age of two to eighteen years

2017 ◽  
Vol 64 (2) ◽  
pp. 213-219 ◽  
Author(s):  
Risa Nomura ◽  
Kentaro Miyai ◽  
Rie Kuge ◽  
Takashi Okura ◽  
Masahiro Goto ◽  
...  
Keyword(s):  
Low T3 Syndrome ◽  
Free T4 ◽  
Central Hypothyroidism ◽  
Free T3 ◽  
Low T3

Prevalence of thyroid dysfunction and effect of contrast medium on thyroid metabolism in cardiac patients undergoing coronary angiography

2013 ◽  
Vol 54 (1) ◽  
pp. 42-47 ◽  
Author(s):  
Paolo Marraccini ◽  
Massimiliano Bianchi ◽  
Antonio Bottoni ◽  
Alessandro Mazzarisi ◽  
Michele Coceani ◽  
...  
Keyword(s):  
Coronary Angiography ◽  
Contrast Medium ◽  
Thyroid Function ◽  
Thyroid Dysfunction ◽  
Thyroid Stimulating Hormone ◽  
Low T3 Syndrome ◽  
Free T4 ◽  
Free T3 ◽  
Iodinated Contrast ◽  
Low T3

Background Iodinated contrast media (CM) may influence thyroid function. Precautions are generally taken in patients with hyperthyroidism, even if subclinical, whereas the risks in patients with hypothyroidism or low triiodothyronine (T3) syndrome are not considered as appreciable. Purpose To assess the presence and type of thyroid dysfunction in patients admitted for coronary angiography (CA), to assess the concentration of free-iodide in five non-ionic CM, and to evaluate changes in thyroid function after CA in patients with low T3 syndrome. Material and Methods We measured free T3, free thyroxine (T4), and thyroid-stimulating hormone (TSH) in 1752 consecutive patients prior to CA and free-iodide in five non-ionic CM. Urinary free-iodide before and 24 h after CA, and thyroid hormone profile 48 h after CA were also made in 17 patients with low T3 syndrome. Patients were followed up for an average duration of 63.5 months. Results The patients were divided into four groups: euthyroidism (60%), low T3 syndrome (28%), hypothyroidism (10%), and hyperthyroidism (2%). The free-iodide resulted far below the recommended limit of 50 μg/mL in all tested CM. In low T3 syndrome, 24-h free-iodide increased after CA from 99.9± 63 ug to 12276±9285 ug (P< 0.0001). A reduction in TSH (4.97±1.1 vs. 4.17±1.1 mUI/mL, P < 0.01) and free T3 (1.44±0.2 vs. 1.25±0.3 pg/mL, P < 0.01), with an increase in free T4 (11.3±2.9 vs. 12.5±3.4 pg/dL, P < 0.001), was found. Patients with functional thyroid disease in the follow-up had a significant lower rate survival compared to euthyroid patients (90.7 vs. 82.2%, P < 0.00001). Conclusion Thyroid dysfunction is frequent in patients who perform a CA, and low T3 syndrome is the predominant feature. The administration of contrast medium may further compromise the thyroid function.

Effects of caloric deprivation on thyroid hormone tissue uptake and generation of low-T3 syndrome

1986 ◽  
Vol 251 (2) ◽  
pp. E156-E163 ◽  
Author(s):  
J. T. van der Heyden ◽  
R. Docter ◽  
H. van Toor ◽  
J. H. Wilson ◽  
G. Hennemann ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Thyroid Hormone ◽  
Production Rate ◽  
Mass Transfer Rate ◽  
Metabolic Clearance ◽  
Low T3 Syndrome ◽  
Serum Free ◽  
Free T3 ◽  
Plasma Pool ◽  
Low T3

Changes in thyroid hormone metabolism in the low-3,5,3'-triiodothyronine (T3) syndrome cannot be fully explained in all conditions by a decrease in 5'-deiodinase activity. Recent observations showed that in rat hepatocytes iodothyronines are taken up by an active transport mechanism. To investigate whether regulation, i.e., inhibition of active transmembraneous transport for iodothyronines in humans may contribute to the generation of the low-T3 syndrome, tracer thyroxine (T4) and T3 kinetic studies were performed in 10 obese subjects before and after 7 days on a 240 kcal diet. Kinetics analyses were performed according to a three-pool model of distribution and metabolism for both T4 and T3. For T4 kinetics, during caloric deprivation serum total T4 and plasma pool did not change and production rate and metabolic clearance rate (MCR) were significantly lower. Despite a significantly higher serum free T4, the mass transfer rate to the rapidly equilibrating pool (REP) and the slowly equilibrating pool (SEP) diminished significantly, leading to smaller tissue pools. For T3 kinetics, both serum total T3, free T3, plasma pool, and production rate diminished significantly, while MCR remained unchanged. Mass transfer rates to the REP and the SEP were lowered by approximately 50%, leading to smaller tissue pools. These changes cannot be fully explained by a similar decrease of serum free T3 (only 25%), indicating a diminished transport efficiency for T3. In conclusion, during caloric restriction, transport of T4 and T3 into tissues is diminished, and this phenomenon is much more pronounced for T4 than for T3.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Low tri-iodothyronine syndrome improve the risk prediction of mortality in patients with acute heart failure

2019 ◽  
Author(s):  
Jian Zhang ◽  
Shengen Liao ◽  
Iokfai Cheang ◽  
Xinyi Lu ◽  
Gongrong Gao ◽  
...  
Keyword(s):  
Heart Failure ◽  
Acute Heart Failure ◽  
Risk Prediction ◽  
Cardiovascular Mortality ◽  
Low T3 Syndrome ◽  
Free T3 ◽  
Net Reclassification Improvement ◽  
Prediction Of Mortality ◽  
Low T3 ◽  
All Cause Mortality

Abstract Background Clinical studies have suggested that low tri-iodothyronine (T3) syndrome negatively affects the clinical outcomes of patients with acute heart failure (AHF). The aim of this prospective cohort study was to evaluate the effect of low T3 syndrome in terms of prognosis and risk predictive potential in AHF.Methods Low T3 syndrome was defined by a low free T3 level (<3.1 pmol/L) accompanied by a normal thyroid-stimulating hormone level. The association between the free T3 level and mortality and the incremental risk prediction were estimated in adjusted models.Results In total, 312 patients with AHF for whom detailed thyroid hormone profiles were available were prospectively enrolled. Seventy-two patients exhibited low T3 syndrome. Over a median follow-up period of 35 months, 121 cumulative deaths occurred. Cardiovascular death was observed in 94 patients. After extensive adjustment for confounders, the low T3 syndrome associated hazard ratio (95% confidence interval) was 1.74 (1.16-2.61, P =0.007) for all-cause mortality and 1.90 (1.21-2.98, P =0.005) for cardiovascular mortality. The regression splines suggested a negative linear relationship between the free T3 level and mortality risk. Considering reclassification, adding low T3 syndrome to the fully adjusted model improved the risk prediction for all-cause mortality (Integrated discrimination improvement [IDI] 2.0%, P = 0.030; net reclassification improvement [NRI] 8.9%, P = 0.232) and cardiovascular mortality (IDI = 2.5%, P = 0.030; NRI 21.3%, P = 0.013).Conclusions Low T3 syndrome reclassified risk prediction for mortality beyond traditional risk factors.

scholarly journals ¿Es necesaria la medición de la T3 para el diagnóstico de hipotiroidismo primario?

2017 ◽  
Vol 2 (3) ◽  
pp. 22-24
Author(s):  
Carlos Alfonso Builes Barrera
Keyword(s):  
Mean Value ◽  
Primary Hypothyroidism ◽  
Free T4 ◽  
Free T3 ◽  
Low T3 ◽  
The Mean ◽  
Las Mujeres

El objetivo de este estudio es evaluar el papel de la T3 en la valoración o diagnóstico de pacientes con hipotiroidismo primario.Se evaluaron 206 registros de pacientes. El 31,6% fueron hombres y el 68,4% mujeres. La edad promedio fue de 46,2, para los hombres 47,8 ±16,6 (rango entre 16 y 87 años) y para las mujeres 45,5±17,5 (rango entre 17 y 83). El valor promedio de TSH fue 75,3± 89 mUI/L (rango entre 10,5 y 490).En los pacientes con TSH entre 10 y 19,9 mUI/L, los valores de T4 libre estuvieron por debajo del rango normal en 31,2%, con un promedio de 0,77±0,06 ng/dl y con un valor promedio de TSH de 17,36 mUI/L. En este grupo (n=48 pacientes), todas las mediciones de T3 (libre o total) estuvieron dentro del rango normal.Los valores bajos de T3 se encontraron en 78 de 206 pacientes (37,8%), cuyo valor promedio de TSH fue 136±115 en el grupo de T3 libre (46 de 124) y 124±123 mUI/L en el grupo de T3 total (32 de 82). En cinco pacientes (6,4%) se encontró T3 baja, con T4 libre dentro del rango normal de referencia, con un valor promedio de TSH de 28,1±11,9 mUI/L, promedio de T4 libre 1,07±0,02 ng/dl.Se confirma la falta de utilidad de medir la T3 en el diagnóstico del hipotiroidismo primario. Los valores bajos de T3 se encontraron en aquellos pacientes con hipotiroidismo primario avanzado (TSH promedio de 136 mUI/L)Abstract The objective of this study is to evaluate the role of T3 in the evaluation or diagnosis of patients with primary hypothyroidism. Two hundred and six patients with primary hypothyroidism were included in the study. 31.6% were male and 68.4% were female. The mean age was 46.2 years for men 47.8 ±16.6 (range 16-87 years) and for women 45.5±17.5 (range 17-83). The mean value of TSH was 75.3± 89 mUI/L (between 10.5 y 490). In the group of patients with TSH level between 10 and 10.9 mUI/L the T4 was low in 31.2%, with a median of 0.77±0.06 ng/ dl, and mean TSH value of 17.36 mUI/L. In that group (n: 48) the T3 measurements was normal in all patients. Low T3 was found in 78 of 206 patients (37.8%), with a mean of TSH of 136±115 in the free T3 group (46 of 124) and mean TSH: 124±123 mUI/L in the total T3 group (32 de 82). In 5 patients (6.4%) we found low T3 with normal free T4 with a mean TSH of 28.1±11.9 mUI/L, free T4 mean 1.07±0.02 ng/ dl. This study confirms the lack of utility of measurement of T3 for the diagnosis of primary hypothyroidism. Low T3 levels were found in cases of severe hypothyroidism ( mean TSH: 136 mUI/L).

Discrepancy between uptake of serum triiodothyronine as measured by albumin and charcoal methods in nonthyroidal illnesses.

1986 ◽  
Vol 32 (12) ◽  
pp. 2183-2187 ◽  
Author(s):  
N Konno ◽  
H Taguchi ◽  
K Hagiwara ◽  
S Taguchi ◽  
Y Hatsukaiwa ◽  
...  
Keyword(s):  
Acute Hepatitis ◽  
Normal Subjects ◽  
High Concentration ◽  
Low T3 Syndrome ◽  
Free T4 ◽  
Low T3

Abstract Triiodothyronine (T3) uptake as determined with albumin (AT3U) and with charcoal (CT3U) as binders were compared for patients with low-T3 syndrome. Both T3U values were identical in normal subjects and in patients with thyroidal disorders, pregnancy, low thyroxin-binding globulin (TBG), or acute hepatitis with high concentration of TBG. In the low-T3 syndrome, AT3U was significantly higher than CT3U (38.5 +/- 7.2% vs 29.4 +/- 4.9%, mean +/- SD, n = 37, p less than 0.001), and this difference increased as TBG and albumin concentrations decreased. Decreasing the concentration of TBG and albumin in serum by dilution increased the AT3U more than the CT3U value. Adding albumin to serum decreased AT3U, but not CT3U, when serum TBG and albumin concentrations were low. The free-thyroxin (T4) index as calculated by the AT3U ratio and T4 more accurately reflects the concentration of free T4 in low-T3 syndrome than does the index calculated from the CT3U ratio and T4. Thus AT3U is determined primarily by changes in TBG and albumin concentrations, so that the free-T4 index based on the AT3U ratio and T4 may be more useful than the CT3U method for evaluating free-T4 concentrations in low-T3 syndrome, which frequently has concomitant decreases in TBG and albumin concentrations.

scholarly journals Low triiodothyronine syndrome as a predictor of poor outcomes in patients undergoing brain tumor surgery: a pilot study

2013 ◽  
Vol 118 (6) ◽  
pp. 1279-1287 ◽  
Author(s):  
Adomas Bunevicius ◽  
Vytenis Deltuva ◽  
Sarunas Tamasauskas ◽  
Arimantas Tamasauskas ◽  
Edward R. Laws ◽  
...  
Keyword(s):  
Brain Tumor ◽  
Depressive Symptoms ◽  
Clinical Outcomes ◽  
Tumor Surgery ◽  
Depression And Anxiety ◽  
Brain Tumor Surgery ◽  
Low T3 Syndrome ◽  
Free T3 ◽  
Symptoms Of Depression ◽  
Low T3

Object A low triiodothyronine (T3) state is highly prevalent and is associated with a poor prognosis in critically ill patients. The authors investigated, in patients undergoing brain tumor surgery, the direct association of a perioperative low T3 syndrome with clinical outcomes and also with symptoms of depression and anxiety. Methods Ninety consecutive patients (71% women, median age 55 years), on admission for brain tumor surgery, were evaluated for sociodemographic and clinical characteristics. Their thyroid function profile was assessed on the morning of brain tumor surgery and on the morning after brain tumor surgery. Patients with free T3 concentrations of 3.1 pmol/L or less were considered to have low T3 syndrome. The patients were evaluated for symptoms of depression and anxiety using the Hospital Anxiety and Depression Scale (HADS) before and after surgery and for clinical outcomes using the Glasgow Outcome Scale (GOS) at discharge. Results After brain tumor surgery, free T3 concentrations decreased (p < 0.001) and the proportion of patients with low T3 levels increased from 38% to 54% (p = 0.02). Lower preoperative (rho = 0.30, p = 0.004) and postoperative (rho = 0.33, p = 0.002) free T3 concentrations correlated with low GOS scores at discharge. Preoperative low T3 syndrome (OR 5.49, 95% CI 1.27–23.69, p = 0.02) and postoperative low T3 syndrome (OR 8.73, 95% CI 1.49–51.21, p = 0.02) both increased risk for unfavorable clinical outcomes (GOS scores < 5) at discharge, after adjusting for age, sex, histological diagnosis of brain tumor, preoperative functional impairment, previous treatment for brain tumor, and depressive symptoms. Preoperative low T3 syndrome increased the risk for preoperative (HADS-depression subscale score ≥ 11; OR 4.12, 95% CI 1.16–14.58, p = 0.03) but not postoperative depressive symptoms independently from sociodemographic and clinical factors. Conclusions Low T3 syndrome is a strong independent predictor of unfavorable clinical outcomes and depressive symptoms, and its diagnosis and preoperative management should be considered in patients undergoing neurosurgery for the treatment of brain tumors.

Induction and prevention of low-T3 syndrome in exercising women

1993 ◽  
Vol 264 (5) ◽  
pp. R924-R930 ◽  
Author(s):  
A. B. Loucks ◽  
R. Callister
Keyword(s):  
Energy Intake ◽  
Reproductive Function ◽  
Energy Availability ◽  
Dietary Energy ◽  
Low T3 Syndrome ◽  
Free T4 ◽  
Reverse T3 ◽  
Dietary Energy Intake ◽  
Low T3 ◽  
Exercising Women

To investigate the influence of exercise on thyroid metabolism, 46 healthy young regularly menstruating sedentary women were randomly assigned to a 3 x 2 experimental design of aerobic exercise and energy availability treatments. Energy availability was defined as dietary energy intake minus energy expenditure during exercise. After 4 days of treatments, low energy availability (8 vs. 30 kcal.kg body wt-1.day-1) had reduced 3,5,3'-triiodothyronine (T3) by 15% and free T3 (fT3) by 18% and had increased thyroxine (T4) by 7% and reverse T3 (rT3) by 24% (all P < 0.01), whereas free T4 (fT4) was unchanged (P = 0.08). Exercise quantity (0 vs. 1,300 kcal/day) and intensity (40 vs. 70% of aerobic capacity) did not affect any thyroid hormone (all P > 0.10). That is, low-T3 syndrome was induced by the energy cost of exercise and was prevented in exercising women by increasing dietary energy intake. Selective observation of low-T3 syndrome in amenorrheic and not in regularly menstruating athletes suggests that exercise may compromise the availability of energy for reproductive function in humans. If so, athletic amenorrhea might be prevented or reversed through dietary reform without reducing exercise quantity or intensity.

scholarly journals High-Dose Thyroid Hormone Replacement in Bexarotene-Induced Central Hypothyroidism

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. A933-A933
Author(s):  
Tony Mathews ◽  
Benjamin Gigliottie
Keyword(s):  
Thyroid Hormone ◽  
Hormone Replacement ◽  
High Dose ◽  
Free T4 ◽  
Hormone Production ◽  
Central Hypothyroidism ◽  
Independent Manner ◽  
Current Case ◽  
Low T3 ◽  
Selective Ligand

Abstract Background: Central hypothyroidism is a rare disorder characterized by a defect in thyroid hormone production by an otherwise normal thyroid gland due to decreased stimulation by TSH. Medications are an uncommon cause. Case Presentation: A 72-year-old man was referred for evaluation of a low TSH. He had a long history of hypothyroidism, euthyroid on levothyroxine, and was diagnosed with cutaneous T cell lymphoma (CTCL). Due to disease progression on dapsone, PUVA and TAR baths, he was started on bexarotene. Soon after, he developed recurrent symptoms of hypothyroidism including fatigue, cold intolerance, dry skin, and myalgias. Workup revealed a TSH of &lt;0.01 ulU/mL (0.27-4.20) with a free T4 of 0.6 ng/dl (0.9-1.7). After evaluation, his levothyroxine dose was increased. Repeat labs 3 months later showed a TSH of &lt;:0.01 with a free T4 0.8 ng/dl and T3 43 ng/dl (80-200). Over several months, levothyroxine titration to a supraphysiologic dose of 800 mcg daily was required, despite optimal administration, to normalize FT4. Given persistent hypothyroid symptoms and a low T3 level, liothyronine 5 mcg BID was added and resulted in clinical and biochemical euthyroidism. Clinical Lessons: Unlike in primary thyroid disorders, the TSH assay is unreliable in central hypothyroidism since values can be low, normal, or even mildly elevated; regardless, TSH has subnormal bioactivity. Ineffectual TSH leads to a low T4, which is a required for diagnosis. Bexarotene, a derivative of Vitamin A, is a retinoid X receptor (RXR) selective ligand approved for the treatment of CTCL. The exact mechanism of bexarotene-induced thyroid dysfunction is not clear, although it involves both central and peripheral effects. Bexarotene inhibits TSH gene expression by decreasing the activity of the thyrotropin β subunit gene promoter in a dose-dependent and thyroxine-independent manner; TSH levels drop as early as 4-8 hours after exposure. Bexarotene also directly lowers T4 and T3 levels, even in athyreotic patients, by negatively impacting deiodinase activity and hepatic conjugation. Stopping bexarotene is often not possible given its effectiveness in CTCL. Therefore, thyroid hormone should be initiated with the goal of achieving a normal FT4, although as the current case demonstrates, massively supraphysiologic doses and/or the addition of liothyronine may be necessary to achieve clinical euthyroidism.

Increased Serum Concentration of Free L-Triiodothyronine in Patients Treated with L-Thyroxine

1983 ◽  
Vol 22 (05) ◽  
pp. 251-254
Author(s):  
R. Schmitz ◽  
H. Bongers ◽  
A. Löw ◽  
J. Mahlstedt ◽  
K. Joseph ◽  
...  
Keyword(s):  
Oral Dose ◽  
Serum Concentration ◽  
Normal Level ◽  
Binding Sites ◽  
Carrier Proteins ◽  
Normal Range ◽  
Free T4 ◽  
Normal Concentration ◽  
Free T3 ◽  
High Doses

This study demonstrates that in spite of measured normal concentrations of carrier proteins one cannot deduce in all cases a normal fT3 from a normal level of TT3 when 1-thyroxine given for diagnostic or therapeutic purposes is present in excess. The displacement of 1-triiodothyronine from its binding sites is shown in 35 patients with non-toxic goitre who received an oral dose of 200 μg 1-thyroxine/die for two weeks. Apart from a significant increase of TT4 (from 7.85 to 14.21 μg/dl ≙ + 81 %) and of fT4 (from 1.58 to 3.7 ng/dl ≙ + 134%) there is only a slight increase in TT3 from 148 to 158 ng/dl (≙ + 10%) after 14 days of treatment. By contrast fT3 rises clearly from 4.97 to 8.07 pg/ml ≙ + 63% (normal range: 2.8-5.6 pg/ml). Compared with the increase of TT3 (+ 10%) the free T3 rises by a factor of 6.3 (63 %/10%). On account of higher affinity of 1-thyroxine to binding proteins the free T4 is influenced to a lesser degree. Compared with the increase of TT4 (+ 81 %) free T4 rises by a factor of 1.6 (134%/81 %). It is supposed that the serum concentration of free T3 can be increased despite a normal concentration of TT3 when 1-thyroxine is present in excess. Therefore, for laboratory work fT3 should be assigned a higher validity than TT3 when patients are treated with comparatively high doses of 1-thyroxine.

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