Rapid adaptations of serum thyrotrophin, triiodothyronine and reverse triiodothyronine levels to short-term starvation and refeeding

1984 ◽  
Vol 105 (2) ◽  
pp. 194-199 ◽  
Author(s):  
Jean-Noel Hugues ◽  
Albert G. Burger ◽  
A. Eugene Pekary ◽  
Jerome M. Hershman
Keyword(s):  
Serum Cortisol ◽  
Starvation Period ◽  
Short Term ◽  
Mean Values ◽  
Fed State ◽  
Tsh Secretion ◽  
The Mean ◽  
Serum Tsh ◽  
Tsh Levels

Abstract. Nutrition influences thyroid function at the level of TSH secretion, at the level of monodeiodination, and possibly elsewhere. In order to study the effect of starvation on TSH secretion, 8 healthy male volunteers fasted for 30 h and were then refed with 800 kcal. Refeeding was performed at 19.00 h and blood was sampled at 20 min intervals until midnight. Control experiments were performed in the same subjects both when they were normally fed and when the starvation period was prolonged a further 5 h until midnight. Starvation decreased serum TSH levels to below 1 mU/l, and without refeeding the nocturnal peak of the TSH nycthemeral rhythm was abolished. With refeeding serum TSH tended to increase towards midnight and was significantly higher than during starvation. However, the serum TSH levels remained significantly below those at the same time of the day in the absence of a preceding starvation period. Serum T3 levels were significantly lower than in the fed state. The mean values were 1.84 ± 0.03 vs 2.30 ± 0.06 nmol/l (120 ±2 vs 150 ± 4 ng/100 ml, mean ± sem P < 0.01). Refeeding did not result in a measurable change in serum T3 concentration (1.80 ± 0.05 nmol/l; 120 ± 3 ng/100 ml, mean ± sem, n.s.). The contrary was true for rT3 levels which increased in starvation and tended to fall with refeeding, but this decrease was not significant. As glucocorticoids have been implicated in the control of monodeiodination and TSH secretion, serum cortisol levels were also measured. They did not differ during the 3 experimental periods. The results show that short-term starvation and refeeding may be a valuable tool for studying in vivo control of TSH secretion. The results show that short-term starvation and refeeding may be a valuable tool for studying in vivo control of TSH secretion.

scholarly journals Impact of Age on Cortisol Secretory Dynamics Basally and as Driven by Nutrient-Withdrawal Stress*

2000 ◽  
Vol 85 (6) ◽  
pp. 2203-2214 ◽  
Author(s):  
M. Bergendahl ◽  
A. Iranmanesh ◽  
T. Mulligan ◽  
J. D. Veldhuis
Keyword(s):  
Healthy Aging ◽  
Metabolic Stress ◽  
Serum Cortisol ◽  
Cortisol Secretion ◽  
Older Individuals ◽  
Short Term ◽  
Fed State ◽  
Aging Men ◽  
The Mean ◽  
Cortisol Release

The present study tests the clinical hypothesis that aging impairs homeostatic adaptations of cortisol secretion to stress. To this end, we implemented a short-term 3.5-day fast as an ethically acceptable metabolic stressor in eight young (ages 18–35 yr) and eight older (ages 60–72 yr) healthy men. Volunteers were studied in randomly ordered fed vs. fasting sessions. To capture the more complex dynamics of cortisol’s feedback control, blood was sampled every 10 min for 24 h for later RIA of serum cortisol concentrations and quantitation of the pulsatile, entropic, and 24-h rhythmic modes of cortisol release using deconvolution analysis, the approximate entropy statistic, and cosine regression, respectively. The stress of fasting elevated the mean (24-h) serum cortisol concentration equivalently in the two age cohorts [i.e. from 7.2± 0.35 to 11.6 ± 0.71 μg/dL in young men and from 7.7 ± 0.39 to 12.6 ± 0.59 μg/dL in older individuals (P &lt; 10−7)]. The rise in integrated cortisol output was driven mechanistically by selective augmentation of cortisol secretory burst mass (P = 0.002). The resultant daily (pulsatile) cortisol secretion rate increased significantly but equally in young (from 94 ± 6.3 to 151 ± 15 μg/dL·day) and older (from 85 ± 5.4 to 145 ± 7.3μ g/dL·day) volunteers (P &lt; 10−4). Nutrient restriction also prompted a marked reduction in the quantifiable regularity of (univariate) cortisol release patterns in both cohorts (P &lt; 10−4). However, older men showed loss of joint synchrony of cortisol and LH secretion even in the fed state, which failed to change with metabolic stress (P &lt; 10−6). In addition, older individuals maintained a premature (early-day) cortisol elevation in the fed state and unexpectedly evolved an anomalous further cortisol phase advance of 99 ± 16 min during fasting (P &lt; 10−5). Caloric deprivation in aging men also disproportionately elevated the mesor of 24-h rhythmic cortisol release (P = 10−7) and elicited a greater increment in the mean day-night variation in cortisol secretory-burst mass (P &lt; 0.01 vs. young controls). Lastly, short-term caloric depletion in older subjects paradoxically normalized their age-associated suppression of the 24-h rhythm in cortisol interburst intervals. In summary, acute metabolic stress in healthy aging men (compared with young individuals) unmasks distinct, albeit complex, disruption of cortisol homeostasis. These dynamic anomalies impact the feedback-dependent and time-sensitive coupling of pulsatile and 24-h rhythmic cortisol secretion. Nutrient-withdrawal stress in the older male heightens the cortisol phase disparity already evident in fed elderly individuals. Conversely, the stress of fasting in young men paradoxically reproduces selected features of the aging unstressed (fed) cortisol axis; viz., abrogation of joint cortisol-LH synchrony and suppression of the normal diurnal variation in cortisol burst frequency. Whether fasting would unveil analogous disruption of feedback-dependent control of the corticotropic axis in healthy aging women is not yet known.

AUGMENTED SECRETION OF TSH IN RESPONSE TO TRH AFTER PRE-TREATMENT WITH DEXAMETHASONE FOR SIX DAYS IN RATS

1976 ◽  
Vol 82 (3) ◽  
pp. 710-714
Author(s):  
Tapio Ranta
Keyword(s):  
Acth Secretion ◽  
Short Term ◽  
Trh Stimulation ◽  
Tsh Secretion ◽  
Pre Treatment ◽  
Dose Levels ◽  
Serum Tsh ◽  
Tsh Levels ◽  
Stimulation Of ◽  
Intact Rats

ABSTRACT Serum TSH and corticosterone concentrations were measured in rats given TRH or exposed to short-term cold, as well as in intact rats, after pretreatment with dexamethasone for six days at two different dose levels (25 and 250 μg/100 g body weight). Both doses increased the secretion of TSH in response to TRH whereas cold-induced TSH secretion was not modified by pre-treatment with dexamethasone. In intact rats serum TSH levels did not differ significantly from controls. In all experiments the steroid blocked ACTH secretion. It was also found that administration of TRH produced a rise in serum corticosterone concentrations. Our results support the view that dexamethasone given for six days facilitates TRH stimulation of the pituitary whilst simultaneously inhibiting the secretion of TRH in response to cold.

CIRCADIAN AND 30 MINUTES VARIATIONS IN SERUM TSH AND THYROID HORMONES IN NORMAL SUBJECTS

1978 ◽  
Vol 89 (3) ◽  
pp. 659-672 ◽  
Author(s):  
Jørgen Weeke ◽  
Hans Jørgen G. Gundersen
Keyword(s):  
Thyroid Hormones ◽  
Statistical Significance ◽  
Mean Amplitude ◽  
Normal Subjects ◽  
Short Term ◽  
Blood Samples ◽  
Young Males ◽  
Tsh Secretion ◽  
The Mean ◽  
Serum Tsh

ABSTRACT Ten normal young males were investigated in order to examine diurnal and short-term variations in serum TSH and serum thyroid hormones. In five subjects blood samples were obtained every 30 min during a 24 h period of daily life. A synchronous diurnal rhythm was found for free T3 and serum TSH with low levels in the day-time and higher levels at night. The mean increase from day to night was 15 and 140 per cent, respectively. There was a tendency to a similar rhythm in free T4, but the increase of 7 per cent fell short of statistical significance. In the other five men blood samples were obtained every 5 min in a 6 to 7 h period starting within the interval from 19.15 to 22.00 h. A significant regular variation with a cycle-length of half an hour was found in TSH, free T3 and free T4. This rhythm accounted for a significant part of the total variation in the levels of TSH, free T3 and free T4. The mean amplitude of the short-term variation is 13, 15 and 11 per cent of the mean level of the respective hormones. The data suggest a pulsatile release of hormones from the thyroid gland governed by a pulsatile TSH secretion.

scholarly journals Thyroid hormones modulate the endocrine and autocrine/paracrine actions of leptin on thyrotropin secretion

2004 ◽  
Vol 183 (1) ◽  
pp. 243-247 ◽  
Author(s):  
M A L Costa da Veiga ◽  
K de Jesus Oliveira ◽  
F H Curty ◽  
C C Pazos de Moura
Keyword(s):  
Body Weight ◽  
Thyroid Hormones ◽  
Inhibitory Action ◽  
Fold Increase ◽  
Short Term ◽  
Tsh Secretion ◽  
Paracrine Actions ◽  
Serum Tsh

We investigated the influence of hypo- and hyperthyroidism on the ability of leptin to modulate TSH secretion. Two hours after receiving leptin (8 μg leptin/100 g BW; s.c.), hyperthyroid rats (10 μg thyroxine (T4)/100 g body weight (BW) for 5 days) showed a 1.7-fold increase in serum TSH (P<0.05); in hypothyroid rats, leptin had no effect. Hemi-pituitaries of hyperthyroid rats incubated with 10−9 and 10−7M leptin showed reductions in TSH release of 40 and 50% respectively (P<0.05); incubation with 1:2000 and 1:500 dilutions of antiserum against leptin resulted in 3- and 4-fold higher TSH release (P<0.05 and P<0.001 respectively). However, in hypothyroid pituitaries leptin or the antiserum had no effect. The results suggest that the in vivo and in vitro responsiveness of TSH to leptin is abolished in hypothyroidism and is preserved in short-term hyperthyroidism, in comparison to previous reports in euthyroidism. In addition, the inhibitory action of pituitary leptin is enhanced in hyperthyroid glands, which may suggest a role for locally produced leptin in the suppression of TSH release associated with hyperthyroidism.

scholarly journals Thyrotropin Levels during Hydrocortisone Infusions That Mimic Fasting-Induced Cortisol Elevations: A Clinical Research Center Study1

1997 ◽  
Vol 82 (11) ◽  
pp. 3700-3704 ◽  
Author(s):  
M. H. Samuels ◽  
P. A. McDaniel
Keyword(s):  
Healthy Subjects ◽  
Serum Cortisol ◽  
Similar Degree ◽  
Trh Stimulation ◽  
Clinical Research Center ◽  
Tsh Secretion ◽  
Cortisol Levels ◽  
High Doses ◽  
Serum Tsh ◽  
Tsh Levels

Both short term fasting and administration of high doses of glucocorticoids lead to marked suppression of serum TSH levels in healthy subjects. However, it is not known whether the more mild serum cortisol elevations seen during fasting can account for fasting-induced TSH suppression. To study this question, eight healthy subjects each underwent three 2-day studies: 1) baseline (ad libitum diet), 2) fasting (56 h of total caloric deprivation), 3) hydrocortisone (HC) infusions at a dose and pulsatile pattern that reproduced cortisol levels measured during each subject’s fasting study. Subjects required 34–46 mg HC/24 h to achieve these cortisol levels. During each study, blood samples were drawn every 15 min during the final 24 h for serum cortisol and TSH levels. A TRH stimulation test was performed at the end of each study. By design, fasting and HC infusions induced similar mild increases in 24-h serum cortisol levels (32% over baseline), with the most significant increases seen between 1400–0200 h. Fasting decreased 24-h mean and pulsatile TSH levels 65% from baseline, whereas HC infusions decreased mean and pulsatile TSH levels 51% from baseline. Daytime (0800–0200 h) TSH levels were identical in the two studies, whereas nocturnal (0200–0800 h) TSH levels during HC infusions fell midway between baseline and fasting studies. Serum total T3 and TSH responses to TRH were decreased to a similar degree by fasting or HC infusions. These results suggest that mild elevations in endogenous cortisol levels may mediate at least in part fasting-induced changes in TSH secretion and thyroid hormone levels. In addition, these data show that near-physiological doses of HC and resulting changes in serum cortisol levels within the normal range can cause significant decreases in serum TSH levels.

scholarly journals Inhibition of pituitary type 2 deiodinase by reverse triiodothyronine does not alter thyroxine-induced inhibition of thyrotropin secretion in hypothyroid rats

2005 ◽  
Vol 153 (3) ◽  
pp. 429-434 ◽  
Author(s):  
P Cettour-Rose ◽  
T J Visser ◽  
A G Burger ◽  
F Rohner-Jeanrenaud
Keyword(s):  
Specific Inhibitor ◽  
Adult Rats ◽  
Reverse T3 ◽  
Brown Adipose ◽  
Tsh Secretion ◽  
Serum T3 ◽  
Serum T4 ◽  
Serum Tsh ◽  
Tsh Levels

Objectives: Intrapituitary triiodothyronine (T3) production plays a pivotal role in the control of TSH secretion. Its production is increased in the presence of decreased serum thyroxine (T4) concentrations and the enzyme responsible, deiodinase type 2 (D2), is highest in hypothyroidism. In order to document the role of this enzyme in adult rats we developed an experimental model that inhibited this enzyme using the specific inhibitor, reverse T3 (rT3). Methods: Hypothyroidism was induced with propylthiouracil (PTU; 0.025 g/l in drinking water) which in addition blocked deiodinase type 1 (D1) activity, responsible for the rapid clearance of rT3 in vivo. During the last 7 days of the experiment, the hypothyroid rats were injected (s.c.) for 4 days with 0.4 or 0.8 nmol T4 per 100 g body weight (bw) per day. For the last 3 days, the same amount of T4 was infused via s.c. minipumps. In additional groups, 25 nmol rT3/100 g bw per day were added to the 3-day infusion of T4. Results: Infusion of 0.4 nmol T4/100 g bw per day did not affect the high serum TSH levels, 0.8 nmol T4/100 g bw per day decreased them to 57% of the hypothyroid values. The infusions of rT3 inhibited D2 activity in all organs where it was measured: the pituitary, brain cortex and brown adipose tissue (BAT). In the pituitary, the activity was 27%, to less than 15% of the activity in hypothyroidism. Despite that, serum TSH levels did not increase, serum T4 concentrations did not change and the changes in serum T3 were minimal. Conclusions: We conclude that in partly hypothyroid rats, a 3-day inhibition of D2 activity, without concomitant change in serum T4 and minimal changes in serum T3 levels, is not able to upregulate TSH secretion and we postulate that this may be a reflection of absent or only minimal changes in circulating T3 concentrations.

Homeopathic Treatment of Subclinical Hypothyroidism—A Series of 19 Cases

Homeopathy ◽  
2021 ◽  
Author(s):  
Luiz Carlos Esteves Grelle ◽  
Luiz Antonio Bastos Camacho
Keyword(s):  
Subclinical Hypothyroidism ◽  
Clinical Importance ◽  
Clinical Problem ◽  
Thyroid Stimulating Hormone ◽  
Exclusion Criteria ◽  
The Mean ◽  
Common Clinical Problem ◽  
Prompt Diagnosis ◽  
Serum Tsh ◽  
Tsh Levels

Abstract Background Subclinical hypothyroidism (SCH) is a common clinical problem. Controversy surrounds the definition, clinical importance, and need for prompt diagnosis and treatment of the mild form of SCH. Aim The aim of the study was to analyze the evolution of serum thyroid stimulating hormone (TSH) levels after a therapeutic homeopathic intervention in women older than 40 years with SCH. Methods This study is a retrospective series of 19 cases of SCH, with serum TSH levels between 5 and 10 mIU/L, treated exclusively with homeopathic medicines prescribed on an individualized basis. Results Nineteen patients were included according to the inclusion and exclusion criteria. Their mean age was 56 years, they were followed for a mean duration of 69 months, the mean number of serum TSH level measurements was 18, and the intervention was successful for 13 patients. Conclusion The homeopathic therapeutic intervention was successful in 68% of the patients, with serum TSH levels back within the normal range (0.5–5.0 mIU/L).

Validation of a new algorithm for the short-term variation of the fetal heart rate: an antepartum prospective study

2018 ◽  
Vol 46 (6) ◽  
pp. 599-604 ◽  
Author(s):  
Christina Kouskouti ◽  
Hella Jonas ◽  
Kerstin Regner ◽  
Pia Ruisinger ◽  
Julia Knabl ◽  
...  
Keyword(s):  
Heart Rate ◽  
Reference Values ◽  
Fetal Heart Rate ◽  
Fetal Heart ◽  
Normal Values ◽  
Short Term ◽  
Mean Values ◽  
Relevant Reference ◽  
Term Variation ◽  
The Mean

Abstract Aims: Currently one of the most widespread systems for the computerized analysis of the fetal heart rate (FHR) is the Dawes-Redman system, where the short-term variation (STV) of the FHR is measured by dividing each minute into 16 segments (STV16). Technical progress has allowed for the development of a new algorithm, which measures the STV by dividing each minute into 240 segments (STV240), thus approximating the beat-to-beat variation. The STV240 still lacks reference values. Our aim was to develop clinically relevant reference values for the STV240 and compare them to the ones for the STV16. Methods: In a single centre, observational study, a total of 228 cardiotocograms were registered and subsequently analyzed with both algorithms (STV240 and STV16). Results: The 95% confidence interval (CI) was calculated for both algorithms. The values of the STV240 were significantly lower in comparison to the ones of the STV16. Not only the mean values but also the 95th percentile of the STV240 lay beneath the existent cut-off value for the STV16. Conclusions: Every clinician using the new algorithm must be aware that the normal values for the STV240 lie beneath the, up until now, established cut-off values for the STV16.

scholarly journals The role of leptin in the regulation of TSH secretion in the fed state: in vivo and in vitro studies

2002 ◽  
Vol 174 (1) ◽  
pp. 121-125 ◽  
Author(s):  
TM Ortiga-Carvalho ◽  
KJ Oliveira ◽  
BA Soares ◽  
CC Pazos-Moura
Keyword(s):  
Fold Increase ◽  
Adult Rats ◽  
Fed State ◽  
Rat Pituitary ◽  
Pituitary Thyroid Axis ◽  
Tsh Secretion ◽  
Thyroid Axis

Leptin has been shown to stimulate the hypothalamus-pituitary-thyroid axis in fasting rodents; however, its role in thyroid axis regulation under physiological conditions is still under investigation. Here it was investigated in freely fed rats whether leptin modulates thyrotroph function in vivo and whether leptin has direct pituitary effects on TSH release. Since leptin is produced in the pituitary, the possibility was also investigated that leptin may be a local regulator of TSH release. TSH was measured by specific RIA. Freely fed adult rats 2 h after being injected with a single s.c. injection of 8 microg leptin/100 g body weight showed a 2-fold increase in serum TSH (P<0.05). Hemi-pituitary explants incubated with 10(-9) and 10(-7) M leptin for 2 h showed a reduced TSH release of 40 and 50% respectively (P<0.05). Conversely, incubation of hemi-pituitary explants with antiserum against leptin, aiming to block the action of locally produced leptin, resulted in higher TSH release (45%, P<0.05). In conclusion, also in the fed state, leptin has an acute stimulatory effect on TSH release in vivo, acting probably at the hypothalamus. However, the direct pituitary effect of leptin is inhibitory and data also provide evidence that in the rat pituitary leptin may act as an autocrine/paracrine inhibitor of TSH release.

scholarly journals Uncertainty in mass-balance trends derived from altimetry: a case study along the EGIG line, central Greenland

2015 ◽  
Vol 61 (226) ◽  
pp. 345-356 ◽  
Author(s):  
Elizabeth M. Morris ◽  
Duncan J. Wingham
Keyword(s):  
Mass Balance ◽  
Greenland Ice Sheet ◽  
Repeated Measurements ◽  
Elevation Change ◽  
Short Term ◽  
Density Profiles ◽  
Mean Values ◽  
Equivalent Mass ◽  
The Mean

AbstractRepeated measurements of density profiles and surface elevation along a 515 km traverse of the Greenland ice sheet are used to determine elevation change rates and the error in determining mass-balance trends from these rates which arises from short-term fluctuations in mass input, compaction and surface density. Mean values of this error, averaged over 100 km sections of the traverse, decrease with time from the start of observations in 2004, with a half-time of ∼4 years. After 7 years the mean error is less than the ice equivalent mass imbalance.

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