Serum concentrations of thyrotropin, thyroxine, triiodothyronine and thyroxine binding globulin in female endurance runners and joggers

1987 ◽  
Vol 114 (1) ◽  
pp. 41-46 ◽  
Author(s):  
H. Hohtari ◽  
A. Pakarinen ◽  
A. Kauppila
Keyword(s):  
Endurance Training ◽  
Anterior Pituitary ◽  
Luteal Phase ◽  
Serum Concentrations ◽  
Endurance Running ◽  
Thyroxine Binding Globulin ◽  
Trh Stimulation ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
Serum Tsh

Abstract. The effects of endurance training and season on the function of the anterior pituitary-thyroid axis were studied in 18 female runners and their 12 controls, and in 13 joggers and their 11 controls in Northern Finland, with a large seasonal difference in environmental factors. The serum concentrations of thyrotropin (TSH), thyroxine (T4), free thyroxine (fT4), triiodothyronine (T3), thyroxine binding globulin (TBG) and oestradiol (E2) were measured during one menstrual cycle in the light training season (autumn) and in the hard training season (spring). The responses of TSH to intravenous TRH stimulation were also measured in the luteal phase of the cycle during the hard training season. Endurance running did not affect the basal or TRH-stimulated serum TSH concentrations, while those of T4 and fT4 in runners were lowered in both seasons and that of T3 in the light training season in relation to control subjects. The serum concentrations of TBG were also significantly lower in runners than their controls in the luteal phase in both seasons. The effect of jogging on thyroid hormones was less pronounced. Serum concentrations of TSH, T4, fT4, T3 and TBG were generally slightly higher in spring than in autumn. Strenuous endurance training seems to have minor changes on the function of the thyroid gland. Depressed T4 levels in runners may rather be due to lowered TBG levels than due to direct effect of training. In spring the function of anterior pituitary-thyroid axis is more active than in autumn.

Lighting conditions affect serum and pituitary TSH in male rats

1990 ◽  
Vol 259 (2) ◽  
pp. E162-E169
Author(s):  
M. L. Laakso ◽  
T. Porkka-Heiskanen ◽  
D. Stenberg ◽  
G. Johansson ◽  
P. T. Mannisto
Keyword(s):  
Diurnal Variation ◽  
Adult Male ◽  
Anterior Pituitary ◽  
Male Rats ◽  
Natural Lighting ◽  
Lighting Conditions ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
Serum Tsh ◽  
Tsh Levels

It has been reported that periodicity of lighting plays a role in the regulation of the function of the hypothalamus-anterior pituitary-thyroid axis in the rat. We studied whether other properties of lighting influence the levels of pituitary and serum thyrotropin (TSH) in adult male rats. The animals were reared 7 days under various lighting conditions, then trunk blood and adenohypophyses were collected at different times of the day, and TSH was measured radioimmunologically. In natural lighting conditions the diurnal variation of plasma and pituitary TSH levels was abolished, and the overall levels of plasma TSH were higher and those of pituitary TSH lower than in ordinary laboratory lighting conditions. The intensity of lighting affected the serum TSH levels; daytime serum TSH decreased in the rats under low daytime illuminances and in those under nighttime twilight instead of darkness. Changing the rate of the lighting transition at dawn and dusk had no influence on the TSH patterns. We conclude that, in addition to periodicity, other features of lighting affect the daily secretion patterns of TSH.

scholarly journals The Hypothalamic-Pituitary-Thyroid Axis in Preterm Infants; Changes in the First 24 Hours of Postnatal Life

2004 ◽  
Vol 89 (6) ◽  
pp. 2824-2831 ◽  
Author(s):  
Nuala Murphy ◽  
Robert Hume ◽  
Hans van Toor ◽  
Tom G. Matthews ◽  
Simon A. Ogston ◽  
...  
Keyword(s):  
Preterm Infants ◽  
Age Groups ◽  
Postnatal Life ◽  
Free T4 ◽  
Thyroxine Binding Globulin ◽  
Time Points ◽  
Pituitary Thyroid Axis ◽  
Serum T4 ◽  
Thyroid Axis ◽  
Immature Group

Abstract 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.

scholarly journals Distinct Roles of Deiodinases on the Phenotype of Mct8 Defect: A Comparison of Eight Different Mouse Genotypes

Endocrinology ◽  
2011 ◽  
Vol 152 (3) ◽  
pp. 1180-1191 ◽  
Author(s):  
Xiao-Hui Liao ◽  
Caterina Di Cosmo ◽  
Alexandra M. Dumitrescu ◽  
Arturo Hernandez ◽  
Jacqueline Van Sande ◽  
...  
Keyword(s):  
Growth Response ◽  
Pituitary Thyroid Axis ◽  
Severe Impairment ◽  
Serum T3 ◽  
Serum T4 ◽  
Thyroid Axis ◽  
Mct8 Deficiency ◽  
The Brain ◽  
Insight Into ◽  
Serum Tsh

Mice deficient in the thyroid hormone (TH) transporter Mct8 (Mct8KO) have increased 5′-deiodination and impaired TH secretion and excretion. These and other unknown mechanisms result in the low-serum T4, high T3, and low rT3 levels characteristic of Mct8 defects. We investigated to what extent each of the 5′-deiodinases (D1, D2) contributes to the serum TH abnormalities of the Mct8KO by generating mice with all combinations of Mct8 and D1 and/or D2 deficiencies and comparing the resulting eight genotypes. Adding D1 deficiency to that of Mct8 corrected the serum TH abnormalities of Mct8KO mice, normalized brain T3 content, and reduced the impaired expression of TH-responsive genes. In contrast, Mct8D2KO mice maintained the serum TH abnormalities of Mct8KO mice. However, the serum TSH level increased 27-fold, suggesting a severely impaired hypothalamo-pituitary-thyroid axis. The brain of Mct8D2KO manifested a pattern of more severe impairment of TH action than Mct8KO alone. In triple Mct8D1D2KO mice, the markedly increased serum TH levels produced milder brain defect than that of Mct8D2KO at the expense of more severe liver thyrotoxicosis. Additionally, we observed that mice deficient in D2 had an unexplained marked reduction in the thyroid growth response to TSH. Our studies on these eight genotypes provide a unique insight into the complex interplay of the deiodinases in the Mct8 defect and suggest that D1 contributes to the increased serum T3 in Mct8 deficiency, whereas D2 mainly functions locally, converting T4 to T3 to compensate for distinct cellular TH depletion in Mct8KO mice.

Influence of meal composition on the postprandial response of the pituitary–thyroid axis

1995 ◽  
Vol 133 (1) ◽  
pp. 75-79 ◽  
Author(s):  
Vinay Kamat ◽  
Wendy L Hecht ◽  
Robert T Rubin
Keyword(s):  
Significant Decline ◽  
Randomized Design ◽  
Postprandial Response ◽  
Pituitary Thyroid Axis ◽  
Tsh Secretion ◽  
Thyroid Axis ◽  
Normal Men ◽  
Allegheny General Hospital ◽  
Serum Tsh ◽  
Meal Composition

Kamat V, Hecht WL, Rubin RT. Influence of meal composition on the postprandial response of the pituitary–thyroid axis. Eur J Endocrinol 1995;133:75–9. ISSN 0804–4643 Ingestion of food can result in an acute decline of serum thyrotropin (TSH) concentrations, but it is not known whether meal composition and/or stomach distension are influential. Normal men and women were given a normocaloric or hypocaloric, isobulk meal at lunch and at dinner in a randomized design. The normocaloric, but not the isobulk, meal resulted in a significant decline in serum TSH at both lunch and dinner; thyroid hormones and cortisol were not affected significantly. These findings suggest that meal composition is influential in the acute postprandial decline of serum TSH in man. A possible mechanism is food-induced elevation of somatostatin and consequent suppression of TSH secretion. Robert T Rubin, Neurosciences Research Center, Allegheny General Hospital, 320 E North Ave. Pittsburgh, PA 15212-4772, USA

scholarly journals The pituitary-thyroid axis in healthy men living under subarctic climatological conditions

2001 ◽  
Vol 169 (1) ◽  
pp. 195-203 ◽  
Author(s):  
J Hassi ◽  
K Sikkila ◽  
A Ruokonen ◽  
J Leppaluoto
Keyword(s):  
Thyroid Hormones ◽  
Climatic Factors ◽  
Feedback Mechanism ◽  
Free Triiodothyronine ◽  
Serum Free ◽  
Healthy Men ◽  
Non Invasive ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
Serum Tsh

In order to evaluate the effects of climatic factors on the secretion of thyroid hormones and TSH in a high latitude population, we have taken serum and urine samples from 20 healthy men from northern Finland (67 degrees -68 degrees N) every 2 months for a period of 14 months. Serum free triiodothyronine (T(3)) levels were lower in February than in August (3.9 vs 4.4 pmol/l, P<0.05) and TSH levels were higher in December than during other months (2.1 vs 1.5-1.7 mU/l, P<0.01). Serum total and free thyroxine (T(4)), total T(3) and reverse T(3) levels and urinary T(4) levels were unchanged. Urinary T(3) levels were significantly higher in winter than in summer. Serum free T(3) correlated highly significantly with the outdoor temperature integrated backwards weekly for 7-56 days (r=0.26 for 1-56 days) from the day when the blood samples were taken. Serum TSH did not show any significant correlation with the thyroid hormones or with the integrated temperature of the previous days, but it did show an inverse and significant correlation (r=-0.31) with the ambient luminosity integrated backwards for 7 days from the day when the blood sample was taken. The gradually increasing correlation between outdoor temperatures and serum free T(3) suggests that the disposal of thyroid hormones is accelerated in winter, leading to low serum free T(3) levels and a high urinary free T(3) excretion. Since there was no correlation between thyroid hormones and serum TSH, the feedback mechanism between TSH and thyroid hormones may not be the only contributing factor, and other factors such as ambient luminosity may at least partly determine serum TSH in these conditions. Also urinary free T(3) appears to be a novel and non-invasive indicator for thyroid physiology.

scholarly journals Type 3 Deiodinase Deficiency Results in Functional Abnormalities at Multiple Levels of the Thyroid Axis

Endocrinology ◽  
2007 ◽  
Vol 148 (12) ◽  
pp. 5680-5687 ◽  
Author(s):  
Arturo Hernandez ◽  
M. Elena Martinez ◽  
Xiao-Hui Liao ◽  
Jacqueline Van Sande ◽  
Samuel Refetoff ◽  
...  
Keyword(s):  
Wild Type ◽  
Central Hypothyroidism ◽  
Trh Stimulation ◽  
Serum T3 ◽  
Antithyroid Treatment ◽  
Pituitary Glands ◽  
Thyroid Axis ◽  
Type 3 ◽  
Serum Tsh ◽  
Hormonal Levels

The type 3 deiodinase (D3) is a selenoenzyme that inactivates thyroid hormones and is highly expressed during development and in the adult central nervous system. We have recently observed that mice lacking D3 activity (D3KO mice) develop perinatal thyrotoxicosis followed in adulthood by a pattern of hormonal levels that is suggestive of central hypothyroidism. In this report we describe the results of additional studies designed to investigate the regulation of the thyroid axis in this unique animal model. Our results demonstrate that the thyroid and pituitary glands of D3KO mice do not respond appropriately to TSH and TRH stimulation, respectively. Furthermore, after induction of severe hypothyroidism by antithyroid treatment, the rise in serum TSH in D3KO mice is only 15% of that observed in wild-type mice. In addition, D3KO animals rendered severely hypothyroid fail to show the expected increase in prepro-TRH mRNA in the paraventricular nucleus of the hypothalamus. Finally, treatment with T3 results in a serum T3 level in D3KO mice that is much higher than that in wild-type mice. This is accompanied by significant weight loss and lethality in mutant animals. In conclusion, the absence of D3 activity results in impaired clearance of T3 and significant defects in the mechanisms regulating the thyroid axis at all levels: hypothalamus, pituitary, and thyroid.

The effect of iodine deficiency and propylthiouracil on the hypothalamo–pituitary–thyroid axis in the neonatal rat

1978 ◽  
Vol 56 (6) ◽  
pp. 950-955 ◽  
Author(s):  
J. H. Dussault ◽  
P. Walker
Keyword(s):  
Tap Water ◽  
Elevated Serum ◽  
Thyroid Stimulating Hormone ◽  
Significant Decline ◽  
Neonatal Rat ◽  
Rapid Rise ◽  
Neonatal Rats ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
Serum Tsh

The effect of chronic propylthiouracil (PTU) and low iodide diet (LID) on the development of the hypothalamo–pituitary–thyroid axis in the rat has been studied. Pregnant and neonatal rats received 0.05% PTU in their drinking water or LID (distilled water and LID: Teklad Mills, Madison, Wisconsin). Control animals received tap water and Purina rat chow ad libitum. Hypothalamic thyrotropin-releasing hormone (TRH), pituitary and serum thyroid-stimulating hormone (THS), and serum thyroxine (T4) and triiodothyronine (T3) were measured by specific double-antibody radioimmunoassay. Both PTU- and LID-exposed animals had low hypothalamic TRH concentrations at 1 day and a rapid rise to peak levels of 2.4 ± 0.4 pg/μg protein (mean ± SEM) between 12 and 24 days in the PTU animals and 3.2 ± 0.4 pg/μg protein between 12 and 18 days in the LID rats. Hypothalamic TRH concentrations remained relatively stable in the PTU animals, whereas in the LID rats, after a brief but significant decline from 24 to 28 days, hypothalamic TRH concentrations rose to the highest values observed at 57 days (3.9 ± 0.5 pg/μg protein). Both groups of animals had elevated serum TSH levels at 1 day, with higher values seen in the PTU group (p < 0.01), and both showed a rapid rise at 12 days. Thereafter, serum TSH concentrations remained high in the PTU rats but declined to stable, albeit elevated, levels by 24 days (1260 ± 140 ng/ml) in the LID animals. Hypothyroidism was confirmed in the PTU animals by undetectable T4 and reduced T3 concentrations. In the LID rats, serum T4 concentrations rose from undetectable levels at 1 day to stable values by 32 days (2.18 ± 0.13 μg/dl). Serum T3 rose to peak values of 157.0 ± 6.9 ng/dl at 32 days and was elevated at all times after 12 days. These data suggest that chronic exposure to PTU or LID results in a marked derangement of the ontogenetic pattern of the hypothalamo–pituitary–thyroid axis. In addition, neonatal rats exposed to LID appear to respond appropriately by preferential T3 production.

Effects of neonatal exposure to TRH on development of the pituitary-thyroid axis in rats

1983 ◽  
Vol 104 (2) ◽  
pp. 201-205 ◽  
Author(s):  
Yoshiaki Kawai ◽  
Mizuo Azukizawa ◽  
Nobuyuki Ashida ◽  
Yuichi Kumahara ◽  
Kiyoshi Miyai
Keyword(s):  
Body Weight ◽  
Hormone Level ◽  
Neonatal Period ◽  
Neonatal Exposure ◽  
Neonatal Rats ◽  
Neonatal Life ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
Serum Tsh ◽  
Tsh Levels

Abstract. TRH (10 and 1000 μg/kg body weight) was administered ip daily to neonatal rats from day 0 to 9 after birth (Neo-TRH rats) and their pituitary-thyroid axis was examined on days 4, 10, 21 and 90. The pituitary TSH content in Neo-TRH rats was significantly smaller than in controls on days 4 and 10. The serum TSH levels in Neo-TRH rats were significantly lower than those in controls on days 4 (male group only), 10 and 21 (only 10 μg/kg group). The serum T4 levels in Neo-TRH rats were lower than in controls on day 10. The reduced pituitary TSH content and serum TSH and T4 were restored to control levels on day 90. However, the response of serum TSH to exogenous TRH (10 μg/kg/ip) was blunted in Neo-TRH rats on days 10, 21 and 90. It is concluded that repetitive administration of TRH during the neonatal period suppresses the pituitary-thyroid axis in neonatal life, even after the basal hormone level has been restored to normal.

scholarly journals Thyroid dysfunction in preterm infants born before 32 gestational weeks

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Hye-Rim Kim ◽  
Young Hwa Jung ◽  
Chang Won Choi ◽  
Hye Rim Chung ◽  
Min-Jae Kang ◽  
...  
Keyword(s):  
Preterm Infants ◽  
Thyroid Dysfunction ◽  
Thyroid Stimulating Hormone ◽  
Thyroid Function Tests ◽  
Academic Center ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
Delayed Maturation ◽  
Levothyroxine Treatment ◽  
Serum Tsh

Abstract Background Thyroid hormones are critical for growth and brain development during the newborn period and infancy. Because of delayed maturation of the hypothalamic-pituitary-thyroid axis in preterm infants, thyroid dysfunction is common, and thyroid stimulating hormone (TSH) elevation is often delayed in preterm infants. The objective of this study was to determine the incidence of thyroid dysfunction requiring levothyroxine treatment and to identify its risk factors in preterm infants. Methods A retrospective cohort study was performed on preterm infants who were born before 32 gestational weeks and admitted to a single tertiary academic center for more than 8 weeks between January 2008 and December 2014. In these infants, serial thyroid function tests (TFTs) measuring serum TSH and free thyroxine (fT4) were routinely performed at 1, 3, and 6 weeks of postnatal age. Results Of the 220 preterm infants enrolled, 180 infants underwent TFTs at 1, 3, and 6 weeks of postnatal age and were included in the study. Of the 180 infants, 35 infants (19.4%) were started on levothyroxine treatment based on the results of serial TFTs. Among the 35 infants who were treated with levothyroxine, 16 infants (45.7%) had normal results on the initial TFT. Three of these 16 infants continued to have normal results on the second TFT. Thyroid dysfunction requiring levothyroxine treatment was significantly associated with maternal pregnancy-induced hypertension (adjusted odds ratio 2.64, 95% confidence interval 1.02–6.81). Conclusions Thyroid dysfunction requiring levothyroxine treatment occurred in nearly one-fifth of preterm infants born before 32 gestational weeks. Nearly half of the preterm infants who were treated with levothyroxine had normal TSH and fT4 levels at 1 week of postnatal age. The findings of the present study suggest that serial TFTs is important to find preterm infants who require levothyroxine treatment.

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