scholarly journals The Effect of Droloxifene and Estrogen on Thyroid Function in Postmenopausal Women1

2000 ◽  
Vol 85 (11) ◽  
pp. 4407-4410
Author(s):  
Ellen Marqusee ◽  
Lewis E. Braverman ◽  
Jennifer E. Lawrence ◽  
Judith S. Carroll ◽  
Ellen W. Seely
Keyword(s):  
Postmenopausal Women ◽  
Treatment Period ◽  
Thyroid Function ◽  
Free T4 ◽  
Double Blind ◽  
Stimulatory Action ◽  
Serum Free ◽  
Serum T4 ◽  
Conjugated Estrogen ◽  
Serum Tsh

Estrogen is known to increase serum T4-binding globulin (TBG) concentrations, thereby increasing serum total T4 concentrations. Serum free T4 concentrations, however, remain normal. Tamoxifen, a selective estrogen receptor modifier (SERM), also raises serum TBG concentrations, but whether newer SERMs with less stimulatory action on the endometrium do so is not known. We, therefore, compared the effect of droloxifene, a SERM, and conjugated equine estrogen on pituitary-thyroid function in normal postmenopausal women. Ten women were treated for 6 weeks with conjugated estrogen (Premarin), 0.625 mg/day, and droloxifene, 60 mg/day, in a double-blind crossover study with an intervening 4-week no-treatment period. We measured serum T4, T3, TBG, free T4 index, and TSH at baseline and at the end of each 6-week period. The baseline values were compared with the 6-week values using paired t tests. The mean (±sd) serum TBG concentrations increased significantly during both treatment periods (baseline, 1.5 ± 0.4 mg/dL; conjugated estrogens, 2.7 ± 0.6 mg/dL; droloxifene, 2.1 ± 0.6 mg/dL; P < 0.001 and P= 0.001, respectively). There were no significant changes in the serum free T4 index. Serum T4 and T3 concentrations increased during both treatment periods, however, the increase was significant only for T4 during the conjugated estrogen treatment period. The serum TSH concentrations increased significantly during both treatment periods (18% during conjugated estrogen and 11% during droloxifene), and the values remained within the normal range in all women. Administration of both conjugated estrogen and droloxifene for 6 weeks increases serum TSH and TBG concentrations, but does not alter free T4 index values in postmenopausal women.

scholarly journals The Effect of Perchlorate, Thiocyanate, and Nitrate on Thyroid Function in Workers Exposed to Perchlorate Long-Term

2005 ◽  
Vol 90 (2) ◽  
pp. 700-706 ◽  
Author(s):  
Lewis E. Braverman ◽  
XueMei He ◽  
Sam Pino ◽  
Mary Cross ◽  
Barbarajean Magnani ◽  
...  
Keyword(s):  
Thyroid Function ◽  
Thyroid Volume ◽  
Production Plant ◽  
Sodium Iodide Symporter ◽  
Free T4 ◽  
High Exposure ◽  
Serum T4 ◽  
Serum Tsh ◽  
Serum And Urine

Perchlorate (ClO4−) and thiocyanate (SCN−) are potent and nitrate (NO3−) a weak competitive inhibitor of the thyroid sodium-iodide symporter. To determine the effects of long-term, high ClO4− exposure on thyroid function, we conducted a study of 29 workers employed for at least 1.7 yr (50% over 5.9 yr) in an ammonium ClO4− production plant in Utah. Serum ClO4−, SCN−, and NO3−; serum T4, free T4 index, total T3, thyroglobulin (Tg), and TSH; 14-h thyroid radioactive iodine uptake (RAIU); and urine iodine (I) and ClO4− were assessed after 3 d off (Pre) and during the last of three 12-h night shifts in the plant (During) and in 12 volunteers (C) not working in the plant. Serum and urine ClO4− were not detected in C; urine ClO4− was not detected in 12 of 29 and was 272 μg/liter in 17 Pre workers; serum ClO4− was not detected in 27 of 29 Pre; and serum and urine ClO4− were markedly elevated during ClO4− exposure to 868 μg/liter and 43 mg/g creatinine, respectively. Serum SCN− and NO3− concentrations were similar in all groups. Thyroid RAIUs were markedly decreased in During compared with Pre (13.5 vs. 21.5%; P < 0.01, paired t) and were associated with an increase in urine I excretion (230 vs. 148 μg I/g Cr; P = 0.02, paired t) but were similar to those in the C group (14.4%). Serum TSH and Tg concentrations were normal and similar in the three groups. Serum T4 (8.3 vs. 7.7 μg/dl), free T4 index (2.4 vs. 2.2), and total T3 (147 vs. 134 ng/dl) were slightly but significantly increased in the During vs. Pre workers (P < 0.01, paired t). Thyroid volumes and patterns by ultrasound were similar in the 29 workers and 12 community volunteers. In conclusion, high ClO4− absorption during three nights work exposure decreased the 14-h thyroid RAIU by 38% in ClO4− production workers compared with the RAIU after 3 d off. However, serum TSH and Tg concentrations and thyroid volume by ultrasound were not affected by ClO4−, suggesting that long-term, intermittent, high exposure to ClO4− does not induce hypothyroidism or goiter in adults.

Thyroid function test changes with adjuvant tamoxifen therapy in postmenopausal women with breast cancer.

1995 ◽  
Vol 13 (4) ◽  
pp. 854-857 ◽  
Author(s):  
C C Mamby ◽  
R R Love ◽  
K E Lee
Keyword(s):  
Postmenopausal Women ◽  
Thyroid Function ◽  
Thyroid Function Test ◽  
Thyroid Stimulating Hormone ◽  
Tamoxifen Therapy ◽  
Controlled Clinical Trial ◽  
Thyroid Function Tests ◽  
Free T4 ◽  
Double Blind ◽  
Before And After

PURPOSE While tamoxifen has been shown to alter concentration of many hormones and their binding globulins, there have been conflicting results regarding its effects on thyroid function tests. We sought to clarify these effects by studying subjects in a controlled clinical trial. PATIENTS AND METHODS We evaluated a subset of postmenopausal women who had participated in a longitudinal, double-blind, randomized, placebo-controlled toxicity study of tamoxifen 10 mg orally, twice daily. There were 14 subjects in both the tamoxifen and placebo groups. Measurement of thyroid-binding globulin (TBG), thyroxine uptake (T-Uptake), thyroxine (T4), and thyroid-stimulating hormone (TSH), and an indirect estimate of the free T4 index (FTI), were made for each subject before and after 3 months of treatment. RESULTS For T-Uptake, T4, and TBG, there were significant increases in the mean change from baseline to 3 months in the tamoxifen group compared with the placebo group (P = .02, .0001, and .003, respectively), while there were no significant changes in the measured TSH and in the calculated FTI. CONCLUSION We conclude that tamoxifen therapy in postmenopausal women results in increased TBG, with secondary increases in measured T-Uptake and T4 following. However, TSH and FTI levels are unchanged, and treated women remain eumetabolic.

scholarly journals SAT-437 Influence of Smoking on Thyroid Function in Japanese Subjects: Longitudinal Study for One Year of On-Off Smoking

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Yasuyo Nakajima ◽  
Sayaka Yamada ◽  
Ayaka Nishikido ◽  
Masayuki Yoshioka ◽  
Akiko Katano-Toki ◽  
...  
Keyword(s):  
Longitudinal Study ◽  
Thyroid Function ◽  
Thyroid Peroxidase ◽  
Free T4 ◽  
Serum Free ◽  
Thyroid Peroxidase Antibody ◽  
One Year ◽  
Old Men ◽  
Serum Tsh ◽  
Tsh Levels

Abstract Recent studies showed that various factors, including age, gender, race, iodine intake, obesity, the thyroid peroxidase antibody (TPO-Ab), and/or smoking, influence the thyroid status. In the present study, we analyzed and investigated the effects of these factors, particularly smoking and the thyroid peroxidase antibody (TPO-Ab) in Japanese euthyroxinemia individuals with serum free T4 level within normal range. A total of 12,289 subjects who underwent health check-ups were analyzed in a cross-sectional and longitudinal study. The mean age of subjects was 50 ± 10 years (age range: 21–88 years). Serum TSH levels and the prevalence of positivity for TPO-Ab increased with age in Japanese euthyroxinemia subjects. Mean and median serum TSH levels increased with age in smokers and non-smokers, but were significantly lower in smokers than in non-smokers among men and women in most age groups; the median 97.5th percentiles of TSH levels were 1.2 mU/liter and 2.9 mU/liter in smokers, and 1.4 mU/liter and 3.9 mU/liter in non-smokers in 31- to 40-year-old men, p<0.01, and 1.4mU/liter and 4.3 mU/liter, and 1.8mU/liter and 6.2 mU/liter in 61- to 70-year-old men, p<0.01. However, smoking had a negligible effect on serum TSH levels in women older than 50 years; 1.3 mU/liter in smokers and 1.6 mU/liter in non-smokers in 31- to 40-year-old women, p<0.01, and 1.5 mU/liter and 1.8 mU/liter in 51- to 60-year-old women, p=0.3. Furthermore, the present study confirmed that serum free T4 levels in men progressively decreased with age, whereas no significant change was observed in women. Smoking did not affect the relationship between age and serum free T4 levels in men or women, except for men in their 20s. Serum TSH levels were significantly higher in subjects with positivity for TPO-Ab than in those with negativity at all ages and in both genders; however, smoking did not affect free T4 levels or the positivity for TPO-Ab. The rate of smokers in men was significantly higher in patients with subclinical hyperthyroidism (25%) than in those with subclinical hypothyroidism (10%, p<0.05). Furthermore, the results of the longitudinal study revealed a significant decrease in serum TSH levels one year after the start of smoking in men (p<0.05). Since smoking appears to lower serum TSH levels in Japanese euthyroxinemia subjects careful consideration of the smoking status is needed when evaluating subclinical thyroid function.

Human cold air habituation is independent of thyroxine and thyrotropin

1992 ◽  
Vol 72 (6) ◽  
pp. 2134-2139 ◽  
Author(s):  
R. L. Hesslink ◽  
M. M. D'Alesandro ◽  
D. W. Armstrong ◽  
H. L. Reed
Keyword(s):  
Single Daily Dose ◽  
Plasma Norepinephrine ◽  
Free T4 ◽  
Cold Air ◽  
Brown Adipose ◽  
Daily Dose ◽  
Before And After ◽  
Serum T4 ◽  
The Relationship ◽  
Serum Tsh

Thyroxine (T4) is required in species possessing brown adipose tissue (BAT) for the maintenance of cold tolerance and adaptation. In humans, who possess negligible quantities of BAT, the importance of T4 has not been demonstrated. We studied the effects of decreased serum T4 and thyrotropin (TSH) on human cold habituation after repeated cold air exposures. Eight men (T3+) received a single daily dose of triiodothyronine (T3; 30 micrograms/day), and another eight men (T3-) received a placebo. All 16 normal thyroid men underwent a standardized cold air test (SCAT) under basal conditions in January and again in March after eighty 30-min 4.4 degrees C air exposures (10/wk). Measurements of basal metabolic rate (BMR), O2 consumption (VO2), mean arterial pressure (MAP), plasma norepinephrine (NE), serum TSH, free and total T4, and free and total T3 were repeated before and after 8 wk of exposure. TSH, free T4, and total T4 were 50% lower for T3+ than for T3- subjects. Total and free T3 were not different between groups. BMR was unchanged after habituation, whereas the cold-stimulated VO2, MAP, and NE were significantly reduced for all subjects in March. The relationship between VO2 and NE (r2 = 0.44, P less than 0.001) during the initial SCAT was unchanged with habituation. We suggest that human cold habituation is independent of major changes in circulating T4 and TSH.

scholarly journals Perchlorate and Thiocyanate Exposure and Thyroid Function in First-Trimester Pregnant Women

2010 ◽  
Vol 95 (7) ◽  
pp. 3207-3215 ◽  
Author(s):  
Elizabeth N. Pearce ◽  
John H. Lazarus ◽  
Peter P. A. Smyth ◽  
Xuemei He ◽  
Daniela Dall'Amico ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Thyroid Function ◽  
Sodium Iodide ◽  
Urinary Iodine ◽  
First Trimester ◽  
Iodine Intake ◽  
Sodium Iodide Symporter ◽  
Free T4 ◽  
Cross Sectional ◽  
Serum Tsh

Context: Thyroid hormone, requiring adequate maternal iodine intake, is critical for fetal neurodevelopment. Perchlorate decreases thyroidal iodine uptake by competitively inhibiting the sodium/iodide symporter. It is unclear whether environmental perchlorate exposure adversely affects thyroid function in pregnant women. Thiocyanate, derived from foods and cigarette smoke, is a less potent competitive sodium/iodide symporter inhibitor than perchlorate. Objective: Our objective was to determine whether environmental perchlorate and/or thiocyanate exposure is associated with alterations in thyroid function in pregnancy. Design and Setting: We conducted a cross-sectional study at health centers in Cardiff, Wales, and Turin, Italy. Patients: During 2002–2006, 22,000 women at less than 16 wk gestation were enrolled in the Controlled Antenatal Thyroid Screening Study. Subsets of 261 hypothyroid/hypothyroxinemic and 526 euthyroid women from Turin and 374 hypothyroid/hypothyroxinemic and 480 euthyroid women from Cardiff were selected based on availability of stored urine samples and thyroid function data. Main Outcome Measures: Urinary iodine, thiocyanate, and perchlorate and serum TSH, free T4 (FT4), and thyroperoxidase antibody were measured. Results: Urinary iodine was low: median 98 μg/liter in Cardiff and 52 μg/liter in Turin. Urine perchlorate was detectable in all women. The median (range) urinary perchlorate concentration was 5 μg/liter (0.04–168 μg/liter) in Turin and 2 μg/liter (0.02–368 μg/liter) in Cardiff. There were no associations between urine perchlorate concentrations and serum TSH or FT4 in the individual euthyroid or hypothyroid/hypothyroxinemic cohorts. In multivariable linear analyses, log perchlorate was not a predictor of serum FT4 or TSH. Conclusions: Low-level perchlorate exposure is ubiquitous but did not affect thyroid function in this cohort of iodine-deficient pregnant women.

Long term changes in serum T4, T3, and TSH in benign thyroid disease

2004 ◽  
Vol 43 (05) ◽  
pp. 158-160 ◽  
Author(s):  
F. Hartmann ◽  
R. Rödel ◽  
M. Reinhardt ◽  
H.-J. Biersack
Keyword(s):  
Thyroid Function ◽  
Small Variation ◽  
Reference Ranges ◽  
Thyroid Function Tests ◽  
Free T4 ◽  
Wide Range ◽  
Serum T4 ◽  
The Individual ◽  
Benign Thyroid

Summary:Aim: The diagnosis of abnormalities of thyroid function is generally based on the measurement of thyroid hormones and TSH in blood. The recommended reference ranges for serum T4 and T3 as well as TSH are quite wide as the result of large differences in thyroid function tests in healthy persons. It has been proven that the individual variation within an individual is small, compared with the variation between individuals. We investigated long term variations of these parameters in patients with and without benign thyroid diseases. Methods: We performed long term follow-up serum determinations of T3, T4, and TSH in a total of 150 patients for a time period of 3 to 13 years. The majority of patients had been put on L-thyroxine. Values of total T3, total T4, free T4 were measured with an almost unmodified test (RIA) over the years. Results: The lowest relative coefficient of variation (<10%) was observed in the group of patients who had been treated with L-thyroxine only. Even for TSH, relatively low cofficients of variation were observed in this group. In the group of patients who had not received any medication, T3 and T4 showed also a variation of 10%. FT4 and TSH revealed a wider range of variation. Even after radioiodine therapy, T3 and T4 showed only a quite small variation, while TSH demonstrated a wide range with a variation of >30%. Conclusion: Our data demonstrate that there are only narrow variations of serum T4 and T3 within individuals with and without thyroid disorders.

scholarly journals Measurement of Serum Free Thyroxine Index May Provide Additional Case Detection Compared to Free Thyroxine in the Diagnosis of Central Hypothyroidism

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
Kevin M. Pantalone ◽  
Betul Hatipoglu ◽  
Manjula K. Gupta ◽  
Laurence Kennedy ◽  
Amir H. Hamrahian
Keyword(s):  
Elevated Serum ◽  
Free Thyroxine ◽  
Pituitary Hormone ◽  
Normal Range ◽  
Free T4 ◽  
Central Hypothyroidism ◽  
Serum Free ◽  
Free Thyroxine Index ◽  
Serum Tsh ◽  
Serum Free Thyroxine

The diagnosis of central hypothyroidism is often suspected in patients with hypothalamic/pituitary pathology, in the setting of low, normal, or even slightly elevated serum TSH and low free thyroxine (FT4). We present four cases of central hypothyroidism (three had known pituitary pathology) in whom central hypothyroidism was diagnosed after the serum free thyroxine index (FTI) was found to be low. All had normal range serum TSH and free thyroxine levels. This report illustrates that the assessment of the serum FTI may be helpful in making the diagnosis of central hypothyroidism in the appropriate clinical setting and when free T4 is in the low-normal range, particularly in patients with multiple anterior pituitary hormone deficiencies and/or with symptoms suggestive of hypothyroidism.

Changes in pituitary and thyroid function with increasing age in young male rats.

1979 ◽  
Vol 237 (3) ◽  
pp. E224 ◽  
Author(s):  
F Azizi
Keyword(s):  
Thyroid Function ◽  
Subcutaneous Administration ◽  
Young Male ◽  
Thyroid Stimulating Hormone ◽  
Male Rats ◽  
Progressive Decline ◽  
Basal Serum ◽  
Serum T4 ◽  
Serum Tsh ◽  
Bovine Tsh

As the age of young adult male rats increased from 30 to 150 days, the serum thyroxine (T4) decreased by 50% and the serum thyroid-stimulating hormone (TSH) increased by 250%. There was no change in the serum triiodothyronine (T3). The increment in serum TSH after injection of thyrotropin-releasing hormone (TRH) was not significantly different at any of the ages studied, but the old animals had significantly lower increments in serum T4 and T3 after subcutaneous administration of bovine TSH. Despite a higher basal serum TSH, the older rats had a lesser increase in serum TSH after thyroidectomy or propylthiouracil. Thus, 1) there is a progressive decline in intrinsic thyroid function between 30 and 150 days of age in male rats, and 2) pituitary TSH response to fall in serum concentration of thyroid hormones is also decreased with age.

scholarly journals Influence of Smoking on Thyroid Function in Japanese Subjects: Longitudinal Study for One Year of On-Off Smoking

2019 ◽  
Vol 3 (12) ◽  
pp. 2385-2396
Author(s):  
Yasuyo Nakajima ◽  
Sayaka Yamada ◽  
Ayaka Nishikido ◽  
Akiko Katano-Toki ◽  
Emi Ishida ◽  
...  
Keyword(s):  
Longitudinal Study ◽  
Thyroid Function ◽  
Smoking Status ◽  
Careful Consideration ◽  
Thyroid Peroxidase ◽  
Free T4 ◽  
Cross Sectional ◽  
Serum Tsh ◽  
Tsh Levels ◽  
Japanese Subjects

Abstract Context We previously identified factors affecting thyroid status, including sex, age, and smoking. Objective In the current study, we increased the number of subjects examined and investigated the effects of these factors, particularly smoking and the thyroid peroxidase antibody (TPO-Ab), in Japanese patients with euthyroxinemia and serum free T4 levels within the normal range. Participants A total of 12,289 subjects who underwent health checkups were analyzed in a cross-sectional and longitudinal study. Results The mean age of subjects was 50 ± 10 years (age range: 21 to 88 years). Serum TSH levels and the prevalence of positivity for TPO-Ab increased with age in Japanese subjects with euthyroxinemia. Mean serum TSH levels were significantly lower in the smoking group than in the nonsmoking group except for women older than 50 years. Serum TSH levels were significantly higher in subjects with positivity for TPO-Ab than in those with negativity at all ages and in both sexes; however, smoking did not affect free T4 levels or positivity for TPO-Ab. Among men, the rate of smokers was significantly higher in patients with subclinical hyperthyroidism (25%) than in those with subclinical hypothyroidism (10%; P < 0.05). Furthermore, the results of the longitudinal study revealed a significant decrease in serum TSH levels 1 year after the start of smoking in men (P < 0.05). Conclusion Because smoking appeared to lower serum TSH levels in Japanese subjects with euthyroxinemia, their smoking status warrants careful consideration when evaluating subclinical thyroid function.

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