Hyperthyroidism causes

Locker GJ, Kotzmann H, Frey B, Messina FC, Strez FR, Weissel M, Laggner AN. Factitious hyperthyroidism causing acute myocardial infarction. Thyroid 1995 5(6) 465-7. 

Galvan G. Hyperthyreosis factitia durch L-Thyroxinabusus ein Fallbericht. [Factitious hyperthyroidism caused by L-thyroxin abuse. Case report.] Acta Med Austriaca 1983 10(2-3) 79-81. 

Thyroid Hormone. Treatment of rats with thyroxin increases hepatic microsomal NADPH oxidation in both male and female rats, with the increase being greater in females. Cytochrome P450 content decreases in the male but not in the female. Hyperthyroidism causes a decrease in gender-dependent monooxygenase reactions and appears to interfere with the ability of androgens to increase the activity of the enzymes responsible. Gender differences are not seen in the response of mice and rabbits to... 

In the past decade several lines of evidence have shown that human chorionic gonadotropin (hCG) is a thyroid stimulator and may cause hyperthyroidism. The basis for the thyrotropic effect of hCG is the structural similarity of hCG to TSH (similar a subunits and unique /3 subunits). In hyperthyroid patients with very high hCG levels, serum TSH may be inappropriately detectable owing to the weak crossreactivity of hCG in the radioimmunoassay for TSH. In patients with hyperthyroidism caused by trophoblastic tumors, serum hCG levels usually exceed 300 units/mL and always exceed 100 units/mL. The mean peak hCG level in normal pregnancy is 50 units/mL. On a molar basis, hCG has only 1/10,000 the activity of pituitary TSH in mouse bioassays. Nevertheless, this thyrotropic activity may be very substantial in patients with trophoblastic tumors, whose serum hCG concentrations may reach 2000 units/mL. 

TABLE 73—5. Treatments for Hyperthyroidism Caused by Graves Disease... 

Cooper DS. Antithyroid drugs for the treatment of hyperthyroidism caused by Graves disease. Endocrinol Metab Clin North Am 1998 27 225-247. 

Continuous administration of PTH or high circulating PTH levels achieved in primary hyperthyroidism causes bone demineralization and osteopenia. Paradoxically, intermittent PTH administration promotes bone growth. The FDA has approved human recombinant PTH (1-34) for treating severe osteoporosis, and full-length PTH is also undergoing chnical trials. 

C. Hyperthyroidism caused by thyroid autonomy C. Hyperthyroidism caused by Graves disease ... 

The improvement of iodine intake in Austria led to a transient increase in hyperthyroidism caused by thyroid autonomy, but decreased thereafter. 

Nervous system Iatrogenic subclinical hyperthyroidism is induced in patients with differentiated thyroid cancer in order to reduce the risk of recurrence. Long-term exogenous subchnical hyperthyroidism causes autonomic nervous system abnormalities, and lower heart rate variability and increased urinary catecholamine excretion are common. After restoration of euthyroidism for a minimum of 6 months in 12 patients who underwent TSH suppressive therapy for more than 10 years, autonomic nervous system abnormalities... 

The selective uptake of iodide ion by the thyroid gland is the basis of radioiodine treatment in hyperthyroidism, mainly with although various other radioactive isotopes ate also used (40,41). With a half-life of eight days, the decay of this isotope produces high energy P-particles which cause selective destmction within a 2 mm sphere of their origin. The y-rays also emitted are not absorbed by the thyroid tissue and are employed for external scanning. 

Non-selective P-adrenergic receptor antagonists (e.g. propranolol) can suppress tachycardia and tremor in patients with hyperthyroidism or tremor caused by... 

Initial daily doses of 10-40 and 100-600 mg are recommended in clinical practice for MMI and PTU, respectively [1, 2]. Several studies have shown that treatment of hyperthyroidism with single daily doses of 10-40 mg of MMI is effective in the induction of euthyroidism in 80-90% of patients within 6 weeks [2]. The aim of the further antithyroid therapy is to maintain euthyroidism with the lowest necessary diug dose. Intrathyroidal diug accumulation is one cause for the efficiency of a single daily dose regimen. Moreover, a once daily dose yields better patients compliance. Single daily doses of PTU have been shown to be less effective in achieving euthyroidism than administration of three divided doses a day. If a once daily... 

Antitrypanosomal Drugs. Table 1 Different treatment strategies depending on the cause of hyperthyroidism... 

Hyperthyroidism (thyrotoxicosis), defined as excessive thyroid activity, causes a state of thyroid hormone excess (thyrotoxicosis) characterized by an increased metabolic rate, increase in body temperature, sweating, tachycardia, tremor, nervousness, increased appetite and loss of weight. Common causes of hyperthyroidism are toxic multinodular goiter, toxic adenoma or diffuse toxic goitre ( Graves disease). Antithyroid diugs (methimazol, carbimazole, propylthiouracil) block thyroid hormone production and are hence suitable for the treatment of hyperthyroidism. 

The skeletal muscle relaxants are contraindicated in patients with known hypersensitivity. Baclofen is contraindicated in skeletal muscle spasms caused by rheumatic disorders. Carisoprodol is contraindicated in patients with a known hypersensitivity to meprobamate. Cyclobenzaprine is contraindicated in patients with a recent myocardial infarction, cardiac conduction disorders, and hyperthyroidism, hi addition, cyclobenzaprine is contraindicated within 14 days of the administration of a monoamine oxidase inhibitor. Oral dantrolene is contraindicated in patients with active hepatic disease and muscle spasm caused by rheumatic disorders and during lactation. See Chapter 30 for information on diazepam. 

About 4.5 million Americans have heart failure (HF). It is the most frequent cause of hospitalization for individuals older than 65 years. Some patients, with treatment, may lead nearly normal lives, whereas more than 50% of individuals with severe HF die each year. HF is a complex clinical syndrome that can result from any number of cardiac or metabolic disorders such as ischemic heart disease, hypertension, or hyperthyroidism. Any condition that impairs the ability of the ventricle to pump blood can lead to HF In HF, die heart... 

The common causes of thyrotoxicosis are shown in Table 41-6.29,30 Thyrotoxicosis can be related to the presence or absence of excess hormone production (hyperthyroidism). Graves disease is the most common cause of hyperthyroidism. Thyrotoxicosis in the elderly is more likely due to toxic thyroid nodules or multinodular goiter than to Graves disease. Excessive intake of thyroid hormone may be due to overtreatment with prescribed therapy. Surreptitious use of thyroid hormones also may occur, especially in health professionals or as a self-remedy for obesity. Thyroid hormones can be obtained easily without a prescription from health food stores or Internet sources. 

Treatment of thyrotoxicosis due to hyperthyroidism is similar, regardless of the underlying cause. The goals of treating hyperthyroidism are to relieve symptoms, to reduce thyroid hormone production to normal levels and achieve biochemical euthyroidism, and to prevent long-term adverse sequelae. 

Interferon-a causes hypothyroidism in up to 39% of patients being treated for hepatitis C infection. Patients may develop a transient thyroiditis with hyperthyroidism prior to becoming hypothyroid. The hypothyroidism may be transient as well. Asians and patients with preexisting anti-TPOAbs are more likely to develop interferon-induced hypothyroidism. The mechanism of interferon-induced hypothyroidism is not known. If LT4 replacement is initiated, it should be stopped after 6 months to re-evaluate the need for replacement therapy. 

Hyperthyroidism State caused by excess production of thyroid hormone. 

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