Thyroid-pituitary function in eight anencephalic infants

1980 ◽  
Vol 93 (4) ◽  
pp. 396-401 ◽  
Author(s):  
S. Grasso ◽  
S. Filetti ◽  
D. Mazzone ◽  
V. Pezzino ◽  
R. Vigo ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Gland ◽  
Pituitary Gland ◽  
Cord Blood ◽  
Pituitary Function ◽  
Hormone Response ◽  
Normal Range ◽  
Thyrotrophin Releasing Hormone ◽  
Bovine Tsh ◽  
Tsh Levels

Abstract. The function of the thyroid pituitary axis was investigated in 8 anencephalic infants with no hypothalamus. Thyrotrophin (TSH), thyroxine (T4), 3,5,3′-triiodothyronine (T3) and 3,3,′5′-triiodothyronine (reverse T3, rT3) were measured in the cord blood in 5 cases and during the first 4 h of life in 3 cases, TSH response to synthetic thyrotrophin-releasing hormone (TRH) (200 μg iv) was carried out in two cases and thyroid hormone response to bovine TSH (5 IU iv) was evaluated in 3 cases. The following results were obtained: 1) The pituitary gland was found in all infants and the thyroid was normal both grossly and by microscopic sections. 2) TSH levels at birth were normal but there was no spontaneous post-delivery surge. 3) T4 and T3 values at delivery were within normal range, but no T3 increase was present after birth. rT3 levels at birth were higher than normal in 3 cases. 4) Administration of TRH caused a marked and rapid TSH release. 5) Thyroid hormone response to TSH was normal. The present findings suggest that in the anencephalic foetus both pituitary TSH-secreting cells and the thyroid gland do develop despite the absence of the hypothalamus and are able to function if adequately stimulated.

EFFECT OF THYROID STATUS ON THE THYROTROPHIN-RELEASING HORMONE-DEGRADING ACTIVITY OF RAT SERUM

1976 ◽  
Vol 71 (1) ◽  
pp. 13-19 ◽  
Author(s):  
N. WHITE ◽  
S. L. JEFFCOATE ◽  
E. C. GRIFFITHS ◽  
K. C. HOOPER
Keyword(s):  
Thyroid Hormone ◽  
Human Serum ◽  
Thyroid Function ◽  
Thyroid Status ◽  
Rat Serum ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Tsh Levels

SUMMARY The TRH-degrading activity of rat serum in vitro is five times more potent than that of human serum. In rats, it is significantly reduced in hypothyroidism (thiouracil-induced) and significantly increased in hyperthyroidism (T3 or T4-induced). This suggests a possible role in the regulation of adenohypophysial-thyroid function which is probably, in turn, dependent on thyroid hormone, rather than TSH, levels.

Effects of intrathyroidal metabolism of thyroxine on thyroid hormone secretion: increased degradation of thyroxine in mouse thyroids stimulated chronically with thyrotrophin

1984 ◽  
Vol 105 (1) ◽  
pp. 57-65 ◽  
Author(s):  
Ken Kubota ◽  
Hidemasa Uchimura ◽  
Tomoaki Mitsuhashi ◽  
Shoo Cheng Chiu ◽  
Nobuaki Kuzuya ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Hormone Secretion ◽  
Plasma Concentrations ◽  
Experimental Period ◽  
Physiological Significance ◽  
The Media ◽  
Bovine Tsh ◽  
Tsh Levels ◽  
Mouse Thyroid

Abstract. Mice were infused continuously with graded doses of bovine TSH (bTSH) and changes in plasma concentrations of bTSH and T4 were measured. Then mice infused with 100 mU TSH per day were sacrificed on days 0, 1, 3 and 5 and their thyroids were excised to determine in vitro secretion of T4, T3 and rT3 during 3 h of incubation. At the end of the incubation, thyroidal contents of T4, T3 and rT3 were also determined after pronase digestion. Plasma bTSH levels were increased on day 1 to a level of 110 μU/ml and remained unchanged thereafter. Plasma T4 concentrations increased approximately 2-fold on day 1, but decreased to initial levels on days 3 and 5. Changes in T4 secretion in vitro paralleled those in plasma T4 concentrations; T4 secretion increased 2-fold on day 1, and decreased to the pre-TSH levels on days 3 and 5. In contrast, T3 secretion increased throughout the experimental period. The T3/T4 ratio in thyroidal secretion in vitro was the same as that in thyroidal contents on days 0 and 1 of TSH infusion, but the former was significantly greater than the latter on days 3 and 5. PTU (5.9 × 10−5 m), a known inhibitor of T4 deiodination, added to the incubation media did not affect T4 secretion on days 0 and 1, but increased T4 secretion on days 3 and 5 to the level of day 1, but did not affect T3 secretion. In the presence of PTU, the T3/T4 ratio in thyroidal secretion did not differ from that in thyroidal contents throughout the experimental period. Secretion of rT3 was increased on days 3 and 5 and PTU augmented this increase. Thyroidal content of rT3 was much increased on days 3 and 5. In contrast, methimazole (10−3 m), which does not inhibit in vitro T4 deiodination, added to the incubation media did not affect T4, T3 and rT3 secretion in vitro. When [125I]T4 was added to the media and incubated with mouse thyroid, no labelled products of T4-deiodination were observed to appear in the media even in mice infused with TSH for 5 days. These results suggest that intrathyroidal metabolism of T4 has physiological significance in controlling thyroid hormone secretion at least in TSH-stimulated thyroids.

Thyrotrophin-releasing hormone (TRH) and hormone secretion from the follicular and C-cells of perfused dog thyroid lobes

1985 ◽  
Vol 109 (4) ◽  
pp. 499-504 ◽  
Author(s):  
E. Iversen ◽  
P. Laurberg
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Gland ◽  
Hormone Secretion ◽  
Inhibitory Effect ◽  
C Cells ◽  
Follicular Cells ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Direct Inhibitory Effect ◽  
Thyroid Secretion

Abstract. Recently we found small amounts of TRH immunoreactivity in the thyroid gland of dogs and pigs. In the present study we investigated if exogenous TRH influences the release of T4, T3 and cAMP from the follicular cells, and calcitonin and somatostatin from the C-cells of perfused dog thyroid lobes. 10−5 mol/l TRH inhibited the TSH induced iodothyronine and cAMP release from the thyroid while 10−8 mol/l TRH had no effect. The relative proportions of T4 and T3 in thyroid secretion were not altered by TRH infusion. TRH did not influence the basal or the Ca++ induced release of somatostatin and calcitonin. Hence TRH has a direct inhibitory effect on the hormone secretion from thyroidal follicular cells. This opens the possibility that TRH in the thyroid participate in the regulation of thyroid hormone secretion. Even though the concentration of TRH found to be effective is high our results may indicate that TRH in the thyroid participates in the regulation of thyroid hormone secretion as an antagonist to TSH.

scholarly journals Modern concepts of primary thyroid gland failure

1996 ◽  
Vol 42 (1) ◽  
pp. 179-182 ◽  
Author(s):  
E C Ridgway
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Gland ◽  
Thyroid Hormones ◽  
Hormone Deficiency ◽  
Clinical Effects ◽  
Normal Range ◽  
Medical Disorder ◽  
Clinical Detection ◽  
Key Genes ◽  
Serum Tsh

Abstract Primary thyroid gland failure is a common medical disorder occurring in mild or severe forms in 10% to 15% of our population. Symptoms may be classical and easy to recognize or very subtle, escaping clinical detection. This disorder is more common in females and increases with advancing age. The most important diagnostic test is measurement of the serum thyrotropin (TSH) concentration, which will increase above the normal range in both mild and severe cases. Most clinical effects of thyroid hormone deficiency can be explained by the "nuclear thyroid hormone hypothesis," which states that thyroid hormones act predominantly by effecting the transcription of key genes in affected tissues. Therapy of hypothyroidism is easy, inexpensive, and precise, involving pure L-thyroxine and measuring dose requirements and efficacy by monitoring serum TSH concentrations.

Bombesin inhibits thyrotrophin secretion in rats

1985 ◽  
Vol 108 (1) ◽  
pp. 79-84 ◽  
Author(s):  
Terunori Mitsuma ◽  
Tsuyoshi Nogimori ◽  
Masahiro Chaya
Keyword(s):  
Thyroid Hormone ◽  
Plasma Concentrations ◽  
Treated Group ◽  
Inhibitory Effect ◽  
Thyrotrophin Releasing Hormone ◽  
Tsh Secretion ◽  
The Central Nervous System ◽  
Thyroid Hormone Levels ◽  
Tsh Levels

Abstract. The effects of peripheral administration of bombesin on thyrotrophin-releasing hormone (TRH) and thvrotrophin (TSH) secretion in rats were studied. Bombesin (200 μg/kg) was injected iv, and the rats were serially decapitated. TRH, TSH and thyroid hormone were measured by radioimmunoassay. The hypothalamic immunoreactive TRH (ir-TRH) content increased significantly after bombesin injection, whereas plasma concentrations tended to decrease, but not significantly. Plasma TSH levels decreased significantly in a dose-related manner with a nadir at 40 min after the injection. Plasma thyroid hormone levels did not change significantly. Plasma ir-TRH and TSH responses to cold were inhibited by bombesin, but the plasma TSH response to TRH was not affected. In the pimozide- or para-chlorophenylalanine pre-treated group, the inhibitory effect of bombesin on TSH levels was prevented, but not in the l-Dopa- or 5-hydroxytryptophan pre-treated group. These drugs alone had no effect on plasma TSH levels in terms of the dose used. The inactivation of TRH immunoreactivity in plasma or hypothalamus in vitro after bombesin injection did not differ from that of the controls. These findings suggest that bombesin acts on the hypothalamus to inhibit TRH release, and that its effects are at least partially modified by amines of the central nervous system.

THE EFFECT OF TRIIODOTHYRONINE AND THYROXINE ON THYROTROPHIN LEVELS IN THE ANTERIOR PITUITARY GLAND AND BLOOD SERUM OF THYROIDECTOMIZED RATS

1966 ◽  
Vol 51 (4) ◽  
pp. 619-624 ◽  
Author(s):  
G. P. van Rees
Keyword(s):  
Thyroid Hormone ◽  
Pituitary Gland ◽  
Blood Serum ◽  
Anterior Pituitary ◽  
Serum Levels ◽  
Pituitary Glands ◽  
Higher Doses ◽  
Serum Tsh ◽  
Tsh Levels ◽  
Intact Rats

ABSTRACT Levels of thyrotrophin were determined in the anterior pituitary glands and blood sera of thyroidectomized rats after treatment with triiodothyronine or thyroxine for two weeks. The effects of increasing doses of both hormones on pituitary TSH levels appeared to be of a biphasic nature: whereas lower doses caused an increase, higher doses did so to a smaller extent or even caused a decrease, while at the same time progressively depressing the serum TSH levels. The highest pituitary levels found in thyroid hormone treated thyroidectomized rats were similar to those found in untreated intact rats, and equal doses of thyroid hormone were necessary to normalize the increased serum levels as well as the decreased pituitary contents in thyroidectomized animals. These findings are interpreted as indicating that in thyroidectomized rats the rate of release of TSH is depressed by lower doses of triiodothyronine and thyroxine than the rate of synthesis. Triiodothyronine was about three times more active than thyroxine.

The thyroid gland and disorders of thyroid function

2020 ◽  
pp. 2284-2302
Author(s):  
Anthony P. Weetman ◽  
Kristien Boelaert
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Gland ◽  
Anterior Pituitary ◽  
Thyroid Dysfunction ◽  
Fetal Brain ◽  
Active Principle ◽  
Receptor Isoforms ◽  
Transcriptional Regulatory ◽  
Thyroid Hormone Levels ◽  
Tsh Levels

The iodine-containing thyroid hormones triiodothyronine (T3) and thyroxine (T4) have diverse effects on metabolism and are essential for normal development, particularly of the fetal brain. The active principle, T3, binds to nuclear receptor isoforms and serves as a transcriptional regulatory factor, thus explaining the protean actions. Thyroid hormone release is regulated by thyrotropin (TSH) from the anterior pituitary, which is itself modulated by the hypothalamic tripeptide, thyrotropin-releasing hormone. A normal TSH level rules out primary thyroid dysfunction, but when TSH levels are abnormal, or when pituitary or hypothalamic abnormalities are possible, it is essential to confirm thyroid status by measuring circulating thyroid hormone levels, which is best achieved by immunoassay of free T3 and free T4. Thyroid-antibody measurement and imaging by scintiscanning are useful in determining the aetiology of thyroid disease when this is not obvious clinically.

STIMULATION WITH THYROTROPHIN-RELEASING HORMONE (TRH) DURING ANTITHYROID TREATMENT

1975 ◽  
Vol 78 (3) ◽  
pp. 461-467 ◽  
Author(s):  
Ulrik Birk Lauridsen ◽  
Carsten Kirkegaard ◽  
Thorkild Friis ◽  
Kaj Siersbæk-Nielsen
Keyword(s):  
Thyroid Gland ◽  
Elevated Serum ◽  
Normal Serum ◽  
Normal Range ◽  
Trh Test ◽  
Duration Of Treatment ◽  
Thyrotrophin Releasing Hormone ◽  
Antithyroid Treatment ◽  
The Mean ◽  
Almost All

ABSTRACT During antithyroid treatment a total of 88 TRH tests was performed in 56 clinical euthyroid patients. 56 % had negative response to TRH (i. e. Δ TSH < 2 μU/ml) after being treated in average 12.6 months and no relation between the duration of treatment and the outcome of the TRH test was found. In the group with positive TRH tests (i. e. Δ TSH > 2 μU/ml) the mean T4 value was slightly decreased (5.8 ± sd 2.5 μg/100 ml) while the mean T3 value was normal (121 ± sd 32 ng/100 ml). The group with negative TRH tests had quite normal serum T4 values (9.3 ± sd 3.1μg/100 ml) but in general high normal or elevated serum T3 values (175 ± sd 31 ng/100 ml). Our results seem to indicate that serum T3 is of greater importance than serum T4 with regard to the outcome of the TRH test. The majority of the cases with negative TRH tests, however, had serum T3 and T4 values within normal range. In almost all patients with a negative TRH test a negative T3 suppression of 131I uptake in the thyroid gland was found while a positive TRH test was not correlated with suppressibility of 131I uptake.

scholarly journals Low TSH levels are not associated with osteoporosis in childhood

2007 ◽  
Vol 157 (2) ◽  
pp. 221-223 ◽  
Author(s):  
Anastasios Papadimitriou ◽  
Dimitrios T Papadimitriou ◽  
Anna Papadopoulou ◽  
Polyxeni Nicolaidou ◽  
Andreas Fretzayas
Keyword(s):  
Thyroid Hormone ◽  
Calcium Phosphate ◽  
Bone Metabolism ◽  
Serum Calcium ◽  
Type I ◽  
Normal Range ◽  
Hormone Levels ◽  
Amino Terminal ◽  
Thyroid Hormone Levels ◽  
Tsh Levels

Introduction: A recent study on TSH receptor (TSHR) null mice suggested that skeletal loss occurring in hyperthyroidism is caused by the low TSH rather than high thyroid hormone levels. The aim of this study was to examine whether low TSH results in osteoporosis in the human. Subjects and methods: We determined bone mineral density (BMD) and markers of bone metabolism in two male siblings aged 9.8 and 6.8 years with isolated TSH deficiency, due to a mutation of the TSH β-subunit gene. BMD was measured in the lumbar spine (L1–L4) by dual-energy X-ray absorptiometry. Laboratory investigation included the determination of serum calcium, phosphate, 25-hydroxy-vitamin D, parathyroid hormone concentrations, and urine calcium (Ca)/creatinine (Cr) ratio. Osteoblast activity was measured by serum bone alkaline phosphatase and osteocalcin levels, and osteoclast activity by urine cross-linked amino-terminal, carboxy-terminal telopeptides of type I collagen and deoxypyridinoline concentrations. Results: BMD of both patients was within the normal range for age and sex; z-scores were −0.55 and −0.23 for patients 1 and 2 respectively. Serum calcium, phosphate, urine Ca/Cr ratio, and specific markers of bone metabolism were also within normal range. Conclusion: In childhood, chronic extremely low TSH levels, in the face of normal thyroid hormone levels, are not related to bone loss.

Benefit of Combined Triiodothyronine (LT3) and Thyroxine (LT4) Treatment in Athyreotic Patients Unresponsive to LT4 Alone

2011 ◽  
Vol 120 (02) ◽  
pp. 121-123 ◽  
Author(s):  
D. Solter ◽  
M. Solter
Keyword(s):  
Thyroid Hormone ◽  
Combination Therapy ◽  
Genetic Basis ◽  
Normal Range ◽  
Serum T3 ◽  
Serum T4 ◽  
Serum Tsh ◽  
Tsh Levels

AbstractDespite some reports, the usefulness of levothyroxine ( LT4) and levotriiodothyronine (LT3) combination therapy in hypothyroidism remains controversial. The objective of this paper is to study a benefit of additional LT3 in athyreotic patients who failed to normalize TSH on LT4 alone even with hyperthyroid serum T4 values.In a survey of 200 athyreotic patients treated between 2006 and 2009, about 7% failed to normalize serum TSH levels following treatment with LT4, though serum T4 values in the hyperthyroid range were achieved. These patients (characterized by serum T4≥160 nmol/L and TSH≥5.0 mIU/L), were additionally treated with 10 μg b. i. d LT3. LT3 and LT4 combination therapy resulted in decreased serum TSH levels into the normal range (12.8 vs. 1.22 mIU/L; p<0.01) and reduced LT4 dose (153.3 vs. 117.5 μg; p<0.01) required for normalization of serum T4 values (170.6 vs. 123.3 nmol/L; p<0.01). Serum T3 values were higher (1.3 vs. 2.26 nmol/L; p<0.01) than those during monotherapy with LT4.Our results indicate a subpopulation of athyreotic patients that could significantly benefit from combined LT4 + LT3 therapy in restoring normal TSH and thyroid hormone patterns. Further research should be undertaken to provide a genetic basis for these findings.

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