Thyroid hormones antidepressants

THYROID HORMONES ANTIDEPRESSANTS - TCAs Possible t antidepressant effect Uncertain May be beneficial but reported cases of nausea and dizziness warn patients to report these symptoms... 

Consider augmentation ) (non-SSRI antidepressant, lithium, thyroid hormone,... 

A number of medical conditions are associated with high rates of depression (see Table 3.4). In some instances, the distinction between MDD and depression due to a general medical condition is largely academic with little bearing on treatment selection. For example, pancreatic cancer may induce depression directly through the release of tumor-secreted substances however, depression in the pancreatic cancer patient is treated with conventional antidepressant medications. In other cases, the diagnostic distinction bears important treatment implications. One commonly cited example is depression occurring in association with hypothyroidism. Patients with depression and hypothyroidism do not respond to antidepressant treatment alone but require a thyroid hormone supplement. 

Drugs that may be affected by estrogens include oral anticoagulants, tricyclic antidepressants, hydantoins, corticosteroids, and thyroid hormones. 

An emerging group of antidepressant interventions comprises several hormones that have been shown to have mood-elevating or mood-modulating effects (see Halbreich, Chapter 17, in this volume). This group includes mostly cortisol suppressors, thyroid hormones, estrogen, and other steroids. However, more recently several other hormones, such as melatonin and oxytocin, were proclaimed as players in the field, but their place is still to be claimed. 

Much of the existing data on the use of thyroid hormones as antidepressants were accumulated by Prange and his colleagues [Prange, in press] and later by Whybrow and colleagues [Whybrow 1996]. 

A body of literature indicates that thyroid hormones are effective as adjuncts to antidepressants and that they enhance antidepressant activity, accelerate rate of response, and decrease treatment resistance. The accumulated literature is convincing that 25-50 mg of T3 is very effective as an adjunct to TGA when added to TGA nonresponders [Aronson et al. 1996]. Of special interest is the short period, 1 week, that is necessary for the T3... 

The mechanisms by which thyroid hormones enhance antidepressant activity are still unknown. It is of interest that thyroid hormone increases net activity of several neurotransmitters that are putatively involved in the pathophysiology of depression in a way that is descriptively similar to that of estrogens. Receptors for the two hormones belong to the same superfamily. As was previously mentioned [Pfaff 1996], these issues are currently being explored, and clarifications are expected shortly. 

Prange AJ, Wilson 1C, Rabon AM, et al Enhancement of imipramine antidepressant activity by thyroid hormone. Am J Psychiatry 126 457-468, 1969... 

Stern RA, Nevels CT, Shelhorse ME, et al Antidepressant and memory effects of combined thyroid hormone treatment and electroconvulsive therapy preliminary findings. Biol Psychiatry 30 623-627, 1991... 

A common mistake is to treat bipolar depression in the same manner that one treats unipolar depression, overlooking the need for a mood stabilizer. In bipolar depression, the first pharmacological intervention should be to start or optimize treatment with a mood stabilizer rather than to start administering an antidepressant medication. In addition, thyroid function should be evaluated, particularly if the patient is taking lithium. Subclinical hypothyroidism, manifested as an increased thyroid-stimulating hormone level and normal triiodothyronine and thyroxine levels, may present as depression in affectively predisposed individuals. In such cases, the addition of thyroid hormones may be beneficial, even if there is no other evidence of hypothyroidism. 

Thyroid Hormone Data from a limited number of controlled studies indicate that, particularly in women, adding triiodothyronine may produce remission in a nonresponder (377). However, most of these studies have been done with TCAs rather than the newer antidepressants. 

Levodopa or dopamine agonists produce diverse dyskinesias as a dose-related phenomenon in patients with Parkinson s disease dose reduction reverses them. Chorea may also develop in patients receiving phenytoin, carbamazepine, amphetamines, lithium, and oral contraceptives, and it resolves with discontinuance of the offending medication. Dystonia has resulted from administration of dopaminergic agents, lithium, serotonin reuptake inhibitors, carbamazepine, and metoclopramide and postural tremor from theophylline, caffeine, lithium, valproic acid, thyroid hormone, tricyclic antidepressants, and isoproterenol. 

Thyroid hormones are not effective and can be detrimental in the management of obesity, abnormal vaginal bleeding, or depression if thyroid hormone levels are normal. Anecdotal reports of a beneficial effect of T3 administered with antidepressants were not confirmed in a controlled study. 

Since thyroid illness is commonly associated with depression, especially in women, it has long been observed that treating the thyroid abnormalities also can reverse the depression. This is especially true for treating hypothyroidism with thyroid hormone replacement (either T3 or T4). It has even been observed that giving supplemental thyroid hormone to depressed patients unresponsive to first-line antidepressants but without overt hypothyroidism can boost the antidepressant response of the first-line antidepressant (thyroid combo in Fig. 7—30). Thyroid hormone is also commonly administered to bipolar patients resistant to mood stabilizers, particularly those with rapid cycling (see discussion of combinations for bipolar disorders below). 

Combination treatments for maintenance of bipolar disorder can include two or more mood stabilizers a mood stabilizer and an atypical antipsychotic a mood stabilizer and/or atypical antipsychotic with a benzodiazepine a mood stabilizer with thyroid hormone and even a mood stabilizer and/or atypical antipsychotic with an antidepressant (Fig. 7—35). 

Thyroid hormones also aid antidepressant action. Guidance points to the combination of tri-iodotyronine (T ) and TCAs as being most effective... 

A precursor to tyrosine and thyroid hormone (thyroxine), phenylalanine acts as an antidepressant, pain reliever, and appetite suppressant helps form collagen and supports memory, concentration, and thinking capabilities. 

Nondietary sources of cyanide include sodium nitro-prusside (a hypotensive agent), succinonitrile (an antidepressant agent), acrylonitrile (used in the plastic industry and as a fumigant to kill dry-wood termites), and tobacco smoke. Chronic exposure to cyanogenic compounds leads to toxic manifestations such as demyelination, lesions of the optic nerves, ataxia (failure of muscle coordination), and depressed thyroid functions. This last effect arises from accumulation of thiocyanate, the detoxified product of cyanide in the body (see below). Thiocyanate inhibits the active uptake of iodide by the thyroid gland and, therefore, the formation of thyroid hormones (Chapter 33). 

Antidepressants selective serotonin reuptake inhibitors, tricyclic antidepressants Antihypertensives felodipine Antibiotics quinolones, isoniazid Bronchodilators albuterol, theophylline Corticosteroids prednisone Dopa agonists levodopa Herbals ma huang, ginseng, ephedra Nonsteroidal anti-inflammatory drugs ibuprofen Stimulants amphetamines, methylphenidate, caffeine, cocaine Sympathomimetics pseudoephedrine Thyroid hormones levothyroxine Toxicity anticholinergics, antihistamines, digoxin Withdrawal alcohol, sedatives... 

So far no definite therapeutic applications have been described for TRH. It has been suggested that it has antidepressant effects, but further controlled studies (M15) did not substantiate the initial reports. The role of TRH as a tool in the treatment of thyroid carcinoma (by increasing uptake of the therapeutic dose of radioiodine by the tumor) (F4) is as yet not confirmed. TRH could be used in the treatment of hypothalamic (tertiary) hypothyroidism, but it does not offer any advantage over thyroid hormone replacement. We have not observed any beneficial effect of TRH in regenerating thyroid remnants after surgery. It has been reported that TRH administration to cows results in an elevation of PRL which increases milk production (K3). Further controlled studies of the applications of TRH in the dairy industry are required. 

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