Thyroid symptoms levothyroxine

The treatment of hypothyroidism involves replacing thyroid hormones. Levothyroxine (T ) is the drug of choice. T has a long half-life (7 days), which allows it to be dosed once daily. Older patients, patients with cardiac disease, or those with chronic hypothyroidism should be started at a lower dose. If cardiac symptoms develop, the dose should be reduced. 

Based on subjective evaluation of thyroid symptoms and neurocognitive test results, there was no difference between a 16-week study of either desiccated thyroid extract (DTE) or levothyroxine in a randomised double-blind crossover study of 70 hypothyroid patients stabilised for 6 months on levothyroxine. However, a greater number of patients preferred DTE (48.6% DTE vs 18.6% levothyroxine) due to subjective judgement of better concentration, sleep and happiness... 

Levothyroxine (T4 ) Activation of nuclear receptors results in gene expression with RNA formation and protein synthesis Hypothyroidism See Table 38-1 maximum effect seen after 6-8 weeks of therapy Toxicity See Table 38-4 for symptoms of thyroid excess... 

Overdosage of levothyroxine causes increased metabolism resulting in increased heat production, with increased sweating and weight loss despite normal or even increased appetite. Accidental or suicidal injection of large amounts of thyroid hormones is exceptional (67). Clinical symptoms do not necessarily correlate well with plasma T4 concentrations and range from anxiety, confusion, or coma to tachycardia, atrial fibrillation, and angina. At least three lethal cases have been reported (SEDA-8, 371). 

Failure of the thyroid to produce sufficient thyroid hormone is the most common cause of hypothyroidism and is known as primary hypothyroidism. Secondary hypothyroidism occurs much less often and results from diminished release of TSH from the pituitary. Treatment of hypothyroidism is achieved by the replacement of thyroid hormone, primarily T4. A synthetic preparation of T4 is available, levothyroxine (Synthroid ), which has been a popular choice for hypothyroidism because of its consistent potency and prolonged duration of action. No toxicity occurs when given in physiological replacement doses. Desiccated animal thyroid is also available at a lesser cost. Overdoses cause symptoms of hyperthyroidism and can be used as a guide in clinical management. Hypothyroidism is not cured by the daily intake of thyroid hormone it is a life-long regimen. 

Adverse effects of thyroid hormone parallel the increase in metabolic rate. The symptoms and signs are those of hyperthyroidism. Symptoms of myocardial ischaemia, atrial fibrillation or heart failure are liable to be provoked by too vigorous therapy or in patients having serious ischaemic heart disease who may even be unable to tolerate optimal therapy. Should they occur levothyroxine must be discontinued for at least a week and begim again at lower dosage. Only slight overdose is needed to precipitate atrial fibrillation in patients over 60 years. 

D Levothyroxine is the drug of choice for hypothyroidism since it provides the necessary hormone without causing the inaease peak effect of Tj administration, levothyroxine is converted to Tj in the periphery. Liotrix contains T4 and T3 in a 4 1 ratio. This combination is not necessary since the T4 is converted to T3 and the short rz> of liotrix requires multiple daily doses. Desiccated thyroid is unreliable in potency since it is standardized to iodine content and not to T4 or T3 content. Triiodothyronine is also not preferred since rapid gastric absorption can lead to hyperthyroid symptoms and can lead to cardiac effects. 

A. An acute ingestion of more than 5 mg of levothyroxine (T4) or 0.75 mg of triiodothyronine (T3) is considered potentially toxic. An adult has survived an ingestion of 48 g of unspecified thyroid tablets a 15-month-old child had moderate symptoms after ingesting 1.5 g of desiccated thyroid. 

Electrolyte balance In patients with metastatic thyroid carcinoma undergoing treatment with I, levothjTOxine is withdrawn and a low iodine diet prescribed to improve treatment efficacy. Significant hyponatremia, associated with symptoms including weakness, dizziness, fainting spells, lethargy, and nausea, has been reported in five patients during levothyroxine withdrawal and a low iodine diet. Combined low sodium intake and the syndrome of inappropriate antidiuretic hormone secretion secondary to hypothyroidism or metastatic disease were proposed as potential underlying mechanisms [13 ]. 

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