Patients with hypothyroidism are usually treated with thyroxine (levothyroxine) only, although both thyroxine and triiodothyronine are secreted by the normal thyroid gland. Whether thyroid secretion ...of triiodothyronine is physiologically important is unknown.
We compared the effects of thyroxine alone with those of thyroxine plus triiodothyronine (liothyronine) in 33 patients with hypothyroidism. Each patient was studied for two five-week periods. During one period, the patient received his or her usual dose of thyroxine. During the other, the patient received a regimen in which 50 microg of the usual dose of thyroxine was replaced by 12.5 microg of triiodothyronine. The order in which each patient received the two treatments was randomized. Biochemical, physiologic, and psychological tests were performed at the end of each treatment period.
The patients had lower serum free and total thyroxine concentrations and higher serum total triiodothyronine concentrations after treatment with thyroxine plus triiodothyronine than after thyroxine alone, whereas the serum thyrotropin concentrations were similar after both treatments. Among 17 scores on tests of cognitive performance and assessments of mood, 6 were better or closer to normal after treatment with thyroxine plus triiodothyronine. Similarly, among 15 visual-analogue scales used to indicate mood and physical status, the results for 10 were significantly better after treatment with thyroxine plus triiodothyronine. The pulse rate and serum sex hormone-binding globulin concentrations were slightly higher after treatment with thyroxine plus triiodothyronine, but blood pressure, serum lipid concentrations, and the results of neurophysiologic tests were similar after the two treatments.
In patients with hypothyroidism, partial substitution of triiodothyronine for thyroxine may improve mood and neuropsychological function; this finding suggests a specific effect of the triiodothyronine normally secreted by the thyroid gland.
Decades of research have established that the biological functions of thyrotropin-releasing hormone (TRH) extend far beyond its role as a regulator of the hypothalamic-pituitary-thyroid axis. Gary et ...al. Gary, K.A., Sevarino, K.A., Yarbrough, G.G., Prange, A.J. Jr., Winokur, A. (2003). The thyrotropin-releasing hormone (TRH) hypothesis of homeostatic regulation: implications for TRH-based therapeutics. J Pharmacol Exp Ther 305(2):410-416. and Yarbrough et al. Yarbrough, G.G., Kamath, J., Winokur, A., Prange, A.J. Jr. (2007). Thyrotropin-releasing hormone (TRH) in the neuroaxis: therapeutic effects reflect physiological functions and molecular actions. Med Hypotheses 69(6):1249-1256. provided a functional framework, predicated on its global homeostatic influences, to conceptualize the numerous interactions of TRH with the central nervous system (CNS) and endocrine system. Herein, we profer a similar analysis to interactions of TRH with the immune system. Autocrine/paracrine cellular signaling motifs of TRH and TRH receptors are expressed in several tissues and organs of the immune system. Consistent with this functional distribution, in vitro and in vivo evidence suggests a critical role for TRH during the developmental stages of the immune system as well as its numerous interactions with the fully developed immune system. Considerable evidence supports a pivotal role for TRH in the pathophysiology of the inflammatory process with specific relevance to the "cytokine-induced sickness behavior" paradigm. These findings, combined with a number of documented clinical actions of TRH strongly support a potential utility of TRH-based therapeutics in select inflammatory disorders. Similar to its global role in behavioral and energy homeostasis a homeostatic role for TRH in its interactions with the immune system is consonant with the large body of available data. Recent advances in the field of immunology provide a significant opportunity for investigation of the TRH-immune system homeostatic hypothesis. Moreover, this hypothesis may provide a foundation for the development of TRH-based therapeutics for certain medical and psychiatric disorders involving immune dysfunction.
To discuss the effects of thyroid dysfunction and thyroid autoimmunity on mental symptoms and disorders in patients with thyroid disease with reference to recent epidemiological, clinical, and ...genetic findings.
During brain development, iodine deficiency, maternal thyroid dysfunction, and neonatal thyroid malformations together with genetic factors contribute to neurological deficit. Most adults with thyroid dysfunction will develop mental symptoms. In hyperthyroidism, adrenergic hyperactivity is a major cause of psychiatric symptoms, and beta-adrenergic antagonists are effective treatment. Most patients with severe hypothyroidism will also demonstrate mental symptoms; however, causality is not so evident as in hyperthyroidism. Polymorphism in deiodinase genes and in transporter genes appears to make an important contribution to the presentation of mental symptoms as well as to the outcome of treatment of hypothyroidism. A thyroid autoimmunity process may by itself contribute to mental symptoms in vulnerable patients. Data from epidemiological studies provide conflicting evidence as to associations between thyroid disorders and mental symptoms.
In the adult brain, compared with the developing brain, brain-thyroid relationships are less apparent but still important. Adrenergic hyperactivity is a major cause of psychiatric symptoms in hyperthyroidism. Genetic factors contribute to the development and treatment outcome of mental disorder in hypothyroidism.
This review defines subclinical hypothyroidism and examines its influence on the occurrence and course of major depression. Recommendations are presented for the identification and treatment of ...patients with coexisting mood disorders and borderline thyroid failure.
The functions of thyrotropin-releasing hormone (TRH) in the central nervous system (CNS) can be conceptualized as performed by four anatomically distinct components that together comprise a general ...TRH homeostatic system. These components are 1) the hypothalamic-hypophysiotropic neuroendocrine system, 2) the brainstem/midbrain/spinal cord system, 3) the limbic/cortical system, and 4) the chronobiological system. We propose that the main neurobiological function of TRH is to promote homeostasis, accomplished through neuronal mechanisms resident in these four integrated systems. This hypothesis offers a unifying basis for understanding the myriad actions of TRH and TRH-related drugs already demonstrated in animals and humans. It is consistent with the traditional role of TRH as a regulator of metabolic homeostasis. An appreciation of the global function of TRH to modulate and normalize CNS activity, along with an appreciation of the inherent limitations of TRH itself as a therapeutic agent, leads to rational expectations of therapeutic benefit from metabolically stable TRH-mimetic drugs in a remarkably broad spectrum of clinical situations, both as monotherapy and as an adjunct to other therapeutic agents. The actions of TRH are numerous and varied. This has been viewed in the past as a conceptual and practical impediment to the development of TRH analogs. Herein, we alternatively propose that these manifold actions should be considered as a rational and positive impetus to the development of TRH-based drugs with the potential for unique and widespread applicability in human illness.
Summary Nearly four decades of research have yielded thousands of publications on the physiology, pharmacology and therapeutic effects of TRH and TRH mimetic analogs. This work addresses both the ...neuroendocrine and the extrahypothalamic actions and functions of the tripeptide. The many reports of clinical effects of TRH in diverse medical conditions, unrelated to pituitary or thyroid function, can appear bewildering, as can its widespread involvement in a plethora of neuronal and physiological processes. Herein, we hypothesize that a logical and causal interrelationship exists between the fundamental molecular and cellular actions of TRH, its broader physiological functions and the therapeutic effects that attend the administration of exogenous TRH and TRH analogs. When viewed from this perspective, the basic neurobiological actions and functions of TRH provide a rational basis for understanding its diverse therapeutic effects. We posit: that the fundamental excitatory actions of TRH throughout the neuroaxis result from blocking various K+ channels linked to G-protein coupled TRH receptors in neurons and pituitary cells in distinct TRH-innervated anatomical pathways; that the functional consequences of blockade of these K+ channels are to enhance neuronal and secretory outputs in TRH regulatory circuits to modulate behavioral and energy homeostasis, and; that in clinical situations the resultant broad and useful therapeutic effects following administration of TRH reflect the state-dependent normalizing effects of activation of these regulatory circuits. In this light, the spectrum of reported clinical effects of TRH agonism remains unique and impressive but is less enigmatic. With the understanding that the neurobiological actions of TRH underlie and are rationally antecedent to its documented, extensive clinical ‘normotrophic’ effects, continued empirical efforts to assess the medical uses of TRH and related drugs seem rational and warranted. We predict that the range of disorders whose symptoms are alleviated by TRH therapy will continue to expand and that TRH agonism could conceivably become a near-universal therapeutic adjunct, particularly in the practice of neuropsychiatric medicine.
To evaluate the prevalence of mood and anxiety disorders in women with treated hyperthyroidism caused by Graves' disease and to compare them with the prevalence of such findings in women without past ...or present thyroid disease.
Thirty inpatient women with treated hyperthyroidism and ophthalmopathy caused by Graves' disease and 45 women hospitalized for treatment of gynecologic disorders such as abnormal vaginal bleeding, benign tumors or infertility were evaluated for the prevalence of mood and anxiety diagnoses using a standard Mini-International Neuropsychiatric Interview and for mood and anxiety ratings using the Profile of Mood States (POMS). At the time of assessment, it was discovered that 14 of 30 women with treated hyperthyroidism caused by Graves' disease were still hyperthyroid, while 16 women were euthyroid.
Significantly greater prevalence of social anxiety disorder, generalized anxiety disorder, major depression and total mood and anxiety disorders, as well as higher symptom scores on the POMS, was found in hyperthyroid women with Graves' disease in comparison with the control group. A prevalence of total anxiety disorder, as well as history of mania or hypomania and lifetime bipolar disorder, but not lifetime unipolar depression, was more frequent in both the euthyroid and the hyperthyroid subgroups of study women in comparison with the control group.
These results confirm a high prevalence of mood and anxiety disorders in women with treated hyperthyroidism and ophthalmopathy caused by Graves' disease. Hyperthyroidism plays a major role in psychiatric morbidity in Graves' disease.
The authors assessed the lifetime history of major depression in 16 subjects with subclinical hypothyroidism and 15 subjects whose thyroid function was completely normal. The lifetime frequency of ...depression was significantly higher in the subjects who met the criteria for subclinical hypothyroidism (56%) than in those who did not (20%), suggesting that subclinical hypothyroidism may lower the threshold for the occurrence of depression.
Fatigue in cancer patients is highly prevalent, predominantly idiopathic, difficult to manage, and has a significant negative impact on quality of life. Thyrotropin-releasing hormone (TRH) exerts ...normotrophic, state-dependent therapeutic effects in a variety of experimental and clinical situations. To evaluate TRH as a treatment for cancer-related fatigue, an ongoing randomized, placebo-controlled, crossover pilot study of breast cancer patients has been initiated and this report presents preliminary observations conducted with three of these patients over 4 consecutive weeks, thereby involving a total of six TRH treatments and six saline controls. Global assessment using both subjective and objective parameters showed that TRH exerted clear anti-fatigue effects in four of the six TRH treatments. These responses were rapid in onset and persisted through the 24 h observation period. No anti-fatigue responses were seen in five of the six saline controls. No unexpected side-effects were seen with TRH administration. These initial findings support the proposal that TRH can ameliorate cancer-related fatigue.
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