Myxoedema

Decreased activity of the thyroid gland results in hypothyroidism and, in severe cases, myxoedema. It is often of immunological origin and the manifestations are low metabolic rate, slow speech, lethargy, bradycardia, increased sensitivity to cold, and mental impairment. Myxoedema includes a characteristic thickening of the skin. Therapy of thyroid tumours is another cause of hypothyroidism. Thyroid deficiency... 

Types of autoimmune diseases vary widely, from organ-specific diseases such as thyroiditis where there may be stimulation (thyrotoxicosis) by antibody against the receptor for pituitary thyroid-stimulating hormone (TSH) or inhibition (myxoedema) by cell destruction probably mediated by NK cells and autoantibody, through to non-... 

In 1858 Schiff removed the thyroid gland from animals and found they could not survive. From his, and later, Horsley s, experiments and from the clinical observations it was concluded that the effects of removal or damage to the thyroid were due to a loss of its internal secretions. Confirmation of this came when patients with myxoedema were successfully treated by thyroid extracts or even by eating thyroid tissue. 

Too little thyroxine may lead to cretinism in children, with poor growth and mental deficiency, or myxoedema in adults, resulting in a slowing down of all body processes. 

Reduced metabolic rate. Patients with myxoedema are very sensitive to thiopentone. 

Krolner B, Jorgensen JV, Nielsen SP. Spinal bone mineral content in myxoedema and thyrotoxicosis. Effects of thyroid hormone(s) and antithyroid treatment. Clin Endocrinol (Oxf) 1983 18(5) 439 16. 

Q4 Weight gain without an increase in appetite is a feature of myxoedema, a severe form of thyroid deficiency. Some of the factors which appear to be involved include reduced metabolic rate, and oxygen and calorie consumption. In addition complexes of protein with polysaccharides and other substances accumulate under the patient s skin to promote water... 

Hypothyroidism is characterized by decreased plasma concentration of thyroid hormones, T3 and T4, with increased concentration of TSH. Severe thyroid hormone deficiency is known as myxoedema. 

Although Brian is tired and weak, with a puffy face and significantly increased body weight, all of which may be observed in myxoedema (a severe form of adult hypothyroidism), his thyroid hormones and TSH concentration are normal. In hypothyroidism T3 and T4 concentrations are usually low, which leads to an increase in TSH because of reduced negative feedback between the thyroid hormones and the anterior pituitary gland. 

Half-life. Plasma half-life, 6 to 7 days which may be increased in pregnancy or myxoedema and decreased in hyperthyroidism. 

Liothyronine Tabs. Liothyronine is the most rapidly effective thyroid hormone, a single dose giving maximum effect within 24 h and passing off over 24—48 h. It is not used in routine treatment of hypothyroidism because its rapid onset of effect can induce heart failure. Its main uses are in myxoedema coma and psychosis, both rare conditions. A specialised use is during the withdrawal of levothyroxine replacement (to permit diagnostic radioiodine scanning) in patients with thyroid carcinoma. 

Myxoedema coma follows prolonged total hormone deficiency and constitutes an emergency. Intravenous therapy is mandatory because of impaired absorption of drugs in this condition. Liothyronine 5-20 micrograms is given every 12 hours. Hydrocortisone i.v. is also needed, as prolonged hypothyroidism may be associated with adrenocortical insufficiency. 

Khaleeli AA. Quinaband-induced thrombocytopenic purpura in a patient with myxoedema coma. BMJ 1976 2(6035) 562-3. 

The age of the patient should influence the behaviour of the injection as ageing will affect vascular blood flow and fatty deposits, but age has not been specifically isolated as a factor in studies to date. In some disease states it is possible to predict that the outcome of an i.m. injection might be different from that in normal patients for example, in patients with circulatory shock, hypotension, congestive heart failure and myxoedema, where blood flow to skeletal muscle is decreased. 

Hypothyroidism. Hypofunction (insufficiency) of the thyroid gland. Autoimmunity is the most common cause of hypothyroidism in iodine-sufficient countries. See also thyroiditis, autoimmune Hashimoto thyroiditis primary myxoedema. 

Primary myxoedema. Atrophic form of diffuse autoimmune thyroiditis. See also thyroiditis, autoimmune. 

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