The Etiology of Abnormal TSH in Veterans Cared by a VA Medical Center - One High Serum Thyrotropin is Associated with Higher 5-Years Mortality.

Objective: By analyzing the etiology of abnormal TSH in randomly selected veteran patients, we set our heart on improving future clinical care/management of the clinical/subclinical hyper- and hypothyroidism in the aging veteran population. Methods: A total of 1100 patients' charts in alphabetical order were selected. Excluded cases of insufficient information, 897 patients' charts were reviewed and analyzed for causes of abnormal TSH. Among them, 602 for the cause of low TSH (below 0.55 uU/mL) and 295 for high TSH (above 4.78 uU/mL) were reviewed retrospectively. Findings: Among the 1100 patients selected, 680 (61.8%) were 60 y or older (female=44, 6.8%); 420 were under 60 y (female=80, 19.0%); significantly more female patients were found in the younger age group (P<0.001). After excluding patients with insufficient data, the most common cause of suppressed TSH is iodine-induced, CT iodinated contrast and betadine use caused 35.0% in the older group (n=126) compared to 23.6% in the younger group(n=57) (P = 0.027). The significant difference is that older veterans received more contrast CTs (P < 0.05 compared to the younger group). In both age groups with concurrent FT4 study, we found four high FT4 among 90 studies, 4.4% overt hyperthyroidism. The second most common cause of suppressed TSH is due to thyroid hormone (TH) replacement in the older group (119 patients, 33.1%) with age > 60y, significantly more frequent compared to the younger group, P<0.001. There is significantly more overt hyperthyroidism, 27.8/%, than the iodine-load induced suppression of TSH, P<0.001, due to 17 patients on TSH suppression therapy after total thyroidectomy for thyroid cancer. Among the 295 patients with elevated TSH, the most common cause of high TSH was due to hypothyroidism on T4 replacement: a total of 128 (59.3%) in the older group (N=216) is, similar to 47 (59.5%) in the younger group (N=79). In both age groups, there were 139 patients with concomitant FT4 measurement; 17 overt hypothyroidism were found, 12.2%. No significant difference is seen in the two age groups. The next most common causes of elevated TSH are CT contrast infusion, 23 (10.6%) in the older group and 7 (8.9%) in the younger group. We find high TSH is associated with a higher death rate of 101/238 (42.4%) in a 5-year follow-up (from 2016 to 2021), as compared to low TSH of 68/238 (28.6%), in the older age group, p<0.03； both were significantly higher than the age- and sex-matched general US population, 19.7%, P<0.01. Conclusion: Even though most, ~ 90%, were subclinical, the suppressed and elevated TSH are associated with severe consequences in CV/CNS and immune-suppression complications in aging veterans. Therefore, cautious use (and more frequent check of TSH) of TH replacement and CT contrast in aging veterans is recommended. The alarming increase in 5 years death rate in older patients with elevated TSH deserves further study.

W-Compound can be used as a Biomarker for Fetal Thyroid Function and a Potential Tool for Screening Congenital Hypothyroidism.

Sulfoconjugation is the major pathway for thyroid hormone (TH) metabolism, converting T4 to inactive metabolites, T4S, rT3S, and T3S in fetus, via sulfotransferases (SULT) and type 3 deiodinase in gestation. Consistent with high production rate of T4S and rT3S, there are high serum sulfated iodothyronine analogs, including T4S, T3S, rT3S, and 3,3'-T2S (T2S), in ovine and human fetal and preterm infants. Fetal TH metabolic pathways predict T2S as the major TH metabolite in the fetus. Since maternal T2S appears to be quantitatively derived from fetal T3 (the active TH), the amount of T2S in the maternal compartment correlates with fetal thyroid function in sheep. In humans, maternal serum contains high levels of radioimmunoassayable T2S; however, it displays as a peak adjacent to but unidentical to synthetic T2S on HLPC and we named it the W-Compound. Levels of W-Compound increase during pregnancy and peak as high as 20-fold to that of nonpregnant women. Maternal serum levels of W-Compound significantly correlate with fetal T4 and W-compound concentrations but not maternal serum T4 in euthyroid or hyperthyroid women, showing a distinct difference between fetal and maternal in TH metabolism. Fetal T2S is actively transferred to the mother via placenta and the quantity of T2S or its metabolite (W-Compound) in maternal compartment reflects fetal thyroid function. Thus, maternal serum W-Compound may be a biomarker for monitoring fetal thyroid function in utero, although more investigations are needed to determine if it can be used as an alternative strategy for screening/managing congenital hypothyroidism due to dysregulated thyroid hormone metabolism.

Maternal 3,3'-Diiodothyronine Sulfate Formation from Guinea Pig Placenta Perfused with 3,3',5-Triodothyronine.

OBJECTIVE: Serum 3, 3',5-triiodothyronine (T3) remains low in near-term fetus to prevent the growing fetus from undue exposure to its active catabolic effect in mammals. The present study was undertaken to gain insight in the role of placenta in T3 metabolism, fetal to maternal transfer of T3, and its metabolites by in situ placenta perfusion with outer-ring labeled [125I]-T3 in pregnant guinea pig, a species showing increased sulfated 3, 3'-diiodothyronine (T2S) levels in maternal serum in late pregnancy (term = 65 days), similarly to humans in pregnancy. MATERIALS AND METHODS: One-pass placenta perfusions performed on pregnant guinea pigs were studied between 58 - 65 days of gestation. In two separate experiments, the umbilical artery of the guinea pig placenta was perfused in situ at 37°C with outer-ring labeled [125I]-T3. Maternal sera and umbilical effluents were obtained for analysis at the end of a 60-minute perfusion, when the steady-state levels of radioactivity were reached in the placenta effluent after 30-minute. RESULTS: Sulfated [125I]-T2S was readily detected in the maternal serum as the major metabolite of T3 following the perfusion of placenta with [125I]-T3, suggesting that placental inner-ring deiodinase and sulfotransferase may play an important role in fetal T3 homeostasis and in the fetal to maternal transfer of sulfated iodothyronine metabolites. CONCLUSIONS: The expression of type 3 deiodinase (D3) and thyroid hormone sulfotransferase activity in placenta may play an important role to protect developing organs against undue exposure to active thyroid hormone in late gestation in the fetus. The combined activities of D3 and sulfotransferase promoted a placental transfer of T2S into maternal circulation. The maternal circulation of T2S is fetal T3 in origin and its role as a fetal thyroid function biomarker deserves further evaluations and studies.

A Homogeneous Time-Resolved Fluorescence Immunoassay Method for the Measurement of Compound W.

OBJECTIVE: Using compound W (a 3,3'-diiodothyronine sulfate [T2S] immuno-crossreactive material)-specific polyclonal antibodies and homogeneous time-resolved fluorescence immunoassay assay techniques (AlphaLISA) to establish an indirect competitive compound W (ICW) quantitative detection method. METHOD: Photosensitive particles (donor beads) coated with compound W or T2S and rabbit anti-W antibody were incubated with biotinylated goat anti-rabbit antibody. This constitutes a detection system with streptavidin-coated acceptor particle. We have optimized the test conditions and evaluated the detection performance. RESULTS: The sensitivity of the method was 5 pg/mL, and the detection range was 5 to 10 000 pg/mL. The intra-assay coefficient of variation averages <10% with stable reproducibility. CONCLUSIONS: The ICW-AlphaLISA shows good stability and high sensitivity and can measure a wide range of compound W levels in extracts of maternal serum samples. This may have clinical application to screen congenital hypothyroidism in utero.

3,3'-Diiodothyronine sulfate cross-reactive material (compound W) in human newborns.

BACKGROUND: Thyrosulfoconjugation appears to facilitate fetal-to-maternal transfer of 3,3'-diiodothyronine-sulfate (T(2)S). Elevated maternal levels of T(2)S cross-reactive material (compound W) are found in humans, with higher levels found in venous cord blood than in arterial samples. These findings are consistent with the postulate that the placenta plays an essential role in compound W production. METHODS: Serum compound W levels were measured by a T(2)S-specific radioimmunoassay in 60 serum samples from newborns with hyperbilirubinemia, age 1-30 d. In addition, 59 maternal serum samples, from day 1 to day 7 after uneventful deliveries, were studied. RESULTS: As compared with day 1, at day 5, the mean (±SE) compound W level fell to 43.5 ± 6.8% (decay half-life (t(1/2)) = 4.12 d) and to 33.7 ± 4.6% (decay t(1/2) = 2.82 d) in the newborn and maternal groups, respectively. In the mothers, the level continued to decline along the same slope through day 7. In the newborns, however, the mean compound W level entered a slower phase of decay after the fifth day with a decay t(1/2) = 10.9 d. CONCLUSION: Compound W is cleared at similar rates in newborn and postpartum maternal sera. This is consistent with the postulate that compound W is produced in the placenta.

CCN1 Induces ß-Catenin Translocation in Esophageal Squamous Cell Carcinoma through Integrin α11.

Aims. Nuclear translocation of ß-catenin is common in many cancers including esophageal squamous cell carcinoma (ESCC). As a mediator of Wnt signaling pathway, nuclear ß-catenin can activate many growth-related genes including CCN1, which in turn can induce ß-catenin translocation. CCN1, a matricellular protein, signals through various integrin receptors in a cell-dependent manner to regulate cell adhesion, proliferation, and survival. Its elevation has been reported in ESCC as well as other esophageal abnormalities such as Barrett's esophagus. The aim of this study is to examine the relationship between CCN1 and ß-catenin in ESCC. Methods and Results. The expression and correlation between CCN1 and ß-catenin in ESCC tissue were examined through immunohistochemistry and further analyzed in both normal esophageal epithelial cells and ESCC cells through microarray, functional blocking and in situ protein ligation. We found that nuclear translocation of ß-catenin in ESCC cells required high level of CCN1 as knockdown of CCN1 in ESCC cells reduced ß-catenin expression and translocation. Furthermore, we found that integrin α(11) was highly expressed in ESCC tumor tissue and functional blocking integrin α(11) diminished CCN1-induced ß-catenin elevation and translocation. Conclusions. Integrin α(11) mediated the effect of CCN1 on ß-catenin in esophageal epithelial cells.

Thyroid function and 3,3'-diiodothyronine sulfate cross-reactive substance (compound W) in maternal hyperthyroidism with antithyroid treatment.

OBJECTIVE: To test whether the serial measurement of maternal levels of compound W, a 3,3'-diiodothyronine sulfate cross-reactive substance, can serve as a potential indicator of fetal thyroid function in pregnant women receiving antithyroid medication. METHODS: Compound W was measured repeatedly in serum of pregnant women with hyperthyroidism treated with antithyroid medication. Free thyroxine levels of mothers and serum thyroid-stimulating hormone levels of 1-day-old neonates were analyzed by local clinical or state laboratories. RESULTS: Use of minimal antithyroid medication impaired the progressive increase of compound W seen in euthyroid mothers during pregnancy. At term, depressed compound W levels in maternal serum were found in 7 of 22 pregnancies; in 1 case, maternal compound W was suppressed and newborn thyroid-stimulating hormone was elevated. Seven mothers with treated hyperthyroidism failed to show an increase in serum levels of compound W after midterm. CONCLUSION: Normal progression of maternal serum compound W may be an index of normal fetal thyroid development in mothers with hyperthyroidism treated with necessary antithyroid medication.

3'-monoiodothyronine sulfate and Triac sulfate are thyroid hormone metabolites in developing sheep.

We used novel 3'-monoiodothyronine sulfate (3'-T1S) and 3,3',5-triiodothyroacetic acid sulfate (TriacS) RIAs to characterize sulfation pathways in fetal thyroid hormone metabolism. 3'-T1S and TriacS levels were measured in serum samples obtained from fetal (n = 21, 94-145 d gestational age), newborn (NB, n = 5), and adult sheep (AD, n = 5) as well as from fetuses after total thyroidectomy (Tx), or sham-operated twin fetuses controls, conducted at gestational age 110-113 d (n = 5). Peak levels (expressed as ng/dL) of both 3'-T1S and TriacS occurred at 130 d gestation. These levels in fetuses were higher than those in NB and AD. In Tx fetuses, there was a significant decrease in the mean serum level of 3'-T1S, but not TriacS. The decrease in 3'-T1S in Tx is similar to that observed for thyroxine sulfate (T4S) and 3,3',5'-triiodothyronine sulfate (rT3S), whereas TriacS levels were not altered in the hypothyroid state, similarly to 3,3',5-triiodothyronine sulfate (T3S). These data demonstrate that 3'-T1S and TriacS are normal thyroid hormone metabolites in ovine serum and that TriacS is likely derived from T3S or from the same precursor(s) as T3S.

Compound W, a 3,3'-diiodothyronine sulfate cross-reactive substance in serum from pregnant women--a potential marker for fetal thyroid function.

Compound W, a 3,3'-diiodothyronine sulfate (T2S) cross-reactive material in maternal serum, was found to be useful as a marker for fetal hypothyroidism. In the present report, we explored its biochemical properties and studied its concentrations in cord and in maternal serum obtained from various gestational periods and at term from different continents. Mean W concentrations, expressed as nmol/L T2S-equivalent, in maternal serum during gestation showed a moderate increase at 20-26 wk (1.57 nmol/L) and an accelerated increase to 34-40 wk (3.59 nmol/L). The mean serum level was relatively low in nonpregnant women (0.17 nmol/L). Compound W levels in cord and maternal serum at term were not significantly different among samples obtained from Taiwan compared with samples from the United States. The mean cord serum "corrected" (by hot acid digestion) concentrations of W were significantly higher than maternal serum concentrations at birth and were also higher in venous than in paired arterial samples, suggesting that the placenta may play a role in its production. We compared a total of 45 iodothyronine analogs by antibody, gel filtration, and HPLC chromatographic studies and found only one compound, N,N-dimethyl-T2S, that has close similarities to Compound W. Further studies are needed.

Targeted disruption of the type 1 selenodeiodinase gene (Dio1) results in marked changes in thyroid hormone economy in mice.

The type 1 deiodinase (D1) is thought to be an important source of T3 in the euthyroid state. To explore the role of the D1 in thyroid hormone economy, a D1-deficient mouse (D1KO) was made by targeted disruption of the Dio1 gene. The general health and reproductive capacity of the D1KO mouse were seemingly unimpaired. In serum, levels of T4 and rT3 were elevated, whereas those of TSH and T3 were unchanged, as were several indices of peripheral thyroid status. It thus appears that the D1 is not essential for the maintenance of a normal serum T3 level in euthyroid mice. However, D1 deficiency resulted in marked changes in the metabolism and excretion of iodothyronines. Fecal excretion of endogenous iodothyronines was greatly increased. Furthermore, when compared with both wild-type and D2-deficient mice, fecal excretion of [125I]iodothyronines was greatly increased in D1KO mice during the 48 h after injection of [125I]T4 or [125I]T3, whereas urinary excretion of [125I]iodide was markedly diminished. From these data it was estimated that a majority of the iodide generated by the D1 was derived from substrates other than T4. Treatment with T3 resulted in a significantly higher serum T3 level and a greater degree of hyperthyroidism in D1KO mice than in wild-type mice. We conclude that, although the D1 is of questionable importance to the wellbeing of the euthyroid mouse, it may play a major role in limiting the detrimental effects of conditions that alter normal thyroid function, including hyperthyroidism and iodine deficiency.

Fetal-to-maternal transfer of thyroid hormone metabolites in late gestation in sheep.

3,3'-Diiodothyronine sulfate (T2S) derived from T3 of fetal origin is transferred to the maternal circulation and contributes significantly to the maternal urinary pool. The present study quantitatively assesses the fetal to maternal transfer of T4 metabolites compared with those of T3. Labeled T4 or T3 was infused intravenously to four singleton fetuses in utero in each group at gestational age 138 +/- 3 d. Maternal and fetal serum and maternal urine samples were collected hourly for 4 h and at 24 h (serum) or in pooled 4-24 h samples (urine). Radioactive metabolites were identified by HPLC and by specific antibody in serum and urine extracts and expressed as percentage infusion dose per liter. The results demonstrate a rapid clearance of labeled T3 from fetal serum (disappearance T(1/2) of 0.7 h versus 2.4 h for T4 in the first 4 h). The metabolites found in fetal serum after labeled T3 infusion were T2S > T3 > T3S; in maternal urine, T2S > unconjugated iodothyronines (UI) > T3S > unknown metabolite (UM). After labeled T4 infusion, the metabolites in fetal serum were rT3 > T3 > T2S > T4S in the first 4 h, and rT3 = T3 = T4S = T2S > T3S at 24 h; in maternal urine we found T2S > UM > UI > T4S > T3S in the first 4 h and UM > T2S > UI in 4-24 h pooled sample. In conclusion, the conversion of T3 to T2S followed by fetal to maternal transfer of T2S and other iodothyronines appears to contribute importantly to maintaining low fetal T3 levels in late gestation.

Alternate pathways of thyroid hormone metabolism.

The major thyroid hormone (TH) secreted by the thyroid gland is thyroxine (T(4)). Triiodothyronine (T(3)), formed chiefly by deiodination of T(4), is the active hormone at the nuclear receptor, and it is generally accepted that deiodination is the major pathway regulating T(3) bioavailability in mammalian tissues. The alternate pathways, sulfation and glucuronidation of the phenolic hydroxyl group of iodothyronines, the oxidative deamination and decarboxylation of the alanine side chain to form iodothyroacetic acids, and ether link cleavage provide additional mechanisms for regulating the supply of active hormone. Sulfation may play a general role in regulation of iodothyronine metabolism, since sulfation of T(4) and T(3) markedly accelerates deiodination to the inactive metabolites, reverse triiodothyronine (rT(3)) and T(2). Sulfoconjugation is prominent during intrauterine development, particularly in the precocial species in the last trimester including humans and sheep, where it may serve both to regulate the supply of T(3), via sulfation followed by deiodination, and to facilitate maternal-fetal exchange of sulfated iodothyronines (e.g., 3,3'-diiodothyronine sulfate [T(2)S]). The resulting low serum T(3) may be important for normal fetal development in the late gestation. The possibility that T(2)S or its derivative, transferred from the fetus and appearing in maternal serum or urine, can serve as a marker of fetal thyroid function is being studied. Glucuronidation of TH often precedes biliary-fecal excretion of hormone. In rats, stimulation of glucuronidation by various drugs and toxins may lead to lower T(4) and T(3) levels, provocation of thyrotropin (TSH) secretion, and goiter. In man, drug induced stimulation of glucuronidation is limited to T(4), and does not usually compromise normal thyroid function. However, in hypothyroid subjects, higher doses of TH may be required to maintain euthyroidism when these drugs are given. In addition, glucuronidates and sulfated iodothyronines can be hydrolyzed to their precursors in gastrointestinal tract and various tissues. Thus, these conjugates can serve as a reservoir for biologically active iodothyronines (e.g., T(4), T(3), or T(2)). The acetic acid derivatives of T(4), tetrac and triac, are minor products in normal thyroid physiology. However, triac has a different pattern of receptor affinity than T(3), binding preferentially to the beta receptor. This makes it useful in the treatment of the syndrome of resistance to thyroid hormone action, where the typical mutation affects only the beta receptor. Thus, adequate binding to certain mutated beta receptors can be achieved without excessive stimulation of alpha receptors, which predominate in the heart. Ether link cleavage of TH is also a minor pathway in normal subjects. However, this pathway may become important during infections, when augmented TH breakdown by ether-link cleavage (ELC) may assist in bactericidal activity. There is a recent claim that decarboxylated derivates of thyronines, that is, monoiodothyronamine (T(1)am) and thyronamine (T(0)am), may be biologically important and have actions different from those of TH. Further information on these interesting derivatives is awaited.

Developmental trends in cord and postpartum serum thyroid hormones in preterm infants.

The purpose of this study was first to clarify postnatal trends in sera T(4), free T(4) (FT(4)), T(4)-binding globulin, TSH, T(3), rT(3), and T(4) sulfate levels in cord and at 7, 14, and 28 d in groups of preterm infants at 23-27 wk (n = 101), 28-30 wk (n = 196), and 31-34 (n = 253) wk gestation, and second to compare these trends to those of term infants and also with cord sera levels of equivalent gestational ages (n = 812; 23-42 wk gestation). In all preterm groups, TSH and rT(3) decrease to below, T(4)-binding globulin increases to within, and T(3) and T(4) sulfate increase to above cord levels of equivalent gestational age. Term infants are hyperthyroxinemic relative to cord and nonpregnant adult levels of T(4). Postnatal T(4) increases are attenuated in 31- to 34-wk infants, absent in 28- to 30-wk infants (although levels are equivalent to gestational age), and crucially reversed in 23- to 27-wk infants. This immature group is hypothyroxinemic relative to other groups and to cord levels of equivalent gestational age. Compared with term infants, postnatal FT(4) increases are lower in 31- to 34-wk infants, attenuated in 28- to 30-wk infants, and absent in 23- to 27-wk infants. The 23- to 27-wk group is distinctive; they are hypothyroxinemic on T(4) levels, yet FT(4) levels are within the cord levels of equivalent gestational age.

The hypothalamic-pituitary-thyroid axis in preterm infants; changes in the first 24 hours of postnatal life.

The purpose of this study was to measure serum T4, free T4, TSH, T3, rT3, T4 sulfate, and thyroxine binding globulin at four time points within the first 24 h of life (cord and 1, 7, and 24 h) in infants between 24 and 34 wk gestation. The infants were subdivided into gestational age groups: 24-27 wk (n = 22); 28-30 wk (n = 26); and 31-34 wk (n = 24). The TSH surge in the first hour of postnatal life was markedly attenuated in infants of 24-27 wk gestation [8 compared with 20 (28-30 wk) and 23 mU/liter (31-34 wk)]. T4 levels in the most immature group declined over the first 24 h, whereas levels increased in the more mature groups [mean cord and 24-h levels: 65 and 59 (NS) vs. 70 and 84 (P < 0.002) vs. 98 and 125 (NS) nmol/liter]. Free T4 and T3 showed only small, transient increases in the most immature group and progressively larger and sustained increases in the other gestational groups. rT3 and T4 sulfate levels in cord serum were higher in the most immature infants, and in all groups levels decreased initially and then variably increased. The features of a severely attenuated or failed hypothalamic-pituitary-thyroid response to delivery critically define this 24- to 27-wk group as distinct from more mature preterm infants.

Effect of treadmill exercise on circulating thyroid hormone measurements.

OBJECTIVES: Effects of exercise on circulating thyroid hormone (TH) values remain controversial. We sought to observe the effect of treadmill exercise on serum TH values in highly selected subjects. METHODS: Twenty-six healthy male military recruits aged 23-27 (mean, 25) years were studied. All had maintained identical diet and physical activity for a week before the test. Serum samples were drawn before (baseline) and immediately, 1, 4, 24, 24 and 48 h after maximal exercise (on a treadmill, Bruce protocol). All subjects completed the protocol with normal ECG results. Specimens were analyzed to measure 3,3',5-triiodothyronine (T(3)), thyroxine (T(4)), free T(4) (FT(4)), free T(3) and thyroid-stimulating hormone (TSH) in the same assays. To determine the possible effect of hemodynamic changes, hematocrit (Hct)-adjusted data were also compared. RESULTS: Hemoconcentration, as reflected by increased Hct, was found immediately after exercise. No significant changes of serum mean TH values before and after exercise were found except for TSH, which increased significantly immediately after exercise (1.72 vs. baseline 1.42 IU/l, p < 0.01). Values for T(3), T(4), and TSH increased significantly immediately after exercise, as compared to other postexercise values. However, the changes became insignificant after Hct adjustment. The FT(4) values showed a reciprocal increase after exercise that became significant after Hct correction. Significantly negative correlation was found between FT(4) and TSH values, but these values were still well within the normal range. CONCLUSIONS: Maximal treadmill exercise does not greatly affect the determination of concentrations of circulating THs.