Ageing thyroid

ECG effects T wave diminished in amplitude or inverted, P-R interval prolonged, Q-T interval shortened. Tests for serum digoxin levels may be altered by electrolyte imbalance, renal impairment, age, thyroid disease, other drugs, or substances in the body which imitate digoxin in radioimmunoassay. 

Carcinoma type Thyroiditis/total (%) Mean age (thyroiditis) Thyroiditis/totai (%) Mean age (thyroiditis) Thyroiditis/totai (%) Mean age (thyroiditis)... 

McCann UD, Shaw EA, Kaplan MM, lodothyronine deiodination reaction types in several rat tissues effects of age, thyroid status, and glucocorticoid treatment. Endocrinology 114 1515 (1984)... 

Rodent 20-day pubertal female with thyroid age of rats at time of vaginal opening. 

The metabolic rate is increased by several hormones including thyi oid hormone, adrenalin and male sex hormones. The increase in metabolic rate caused by male sex hormones explains why males have slightly higher average metabolic rates than females of the same size and age. Living in a cold climate increases the metabolic rate because the cold stimulates thyroid hormone production and this hormone increases heat output of the body, while living in a warm climate causes the metabolic rate to decrease. 

Hyperthyroidism is much less common than hypothyroidism. In NHANES III,1 1.3% of the population was hyperthyroid (0.5% overt, 0.8% subclinical), with the highest incidences in women overall and in men and women in the 20 to 39 and over 80 years of age groups. The Colorado Thyroid Health Study2 showed a hyperthyroid incidence of 2.2% (2.1% subclinical). 

No effects of lead on thyroid function have been found in children. Thirty-six male and 32 female children ranging in age from 11 months to 7 years (median age of 25 months) took part in a study of the effects of lead exposure on thyroid function in inner city children (Siegel et al. 1989). Blood lead levels,... 

Hormonal actions occur during sensitive periods in development, in adult life during natural endocrine cycles and in response to experience as well as during the aging process (see Ch. 30). As a result of their fundamental actions on cellular processes and genomic activity and of the control of their secretion by environmental signals, steroid and thyroid hormone actions on the brain provide unique insights into the plasticity of the brain and behavior (see also Ch. 50). 

Ah-responsive and Ah-nonresponsive strains females, age 10 weeks given single ip injection of 50 mg/kg BW killed after 7 days Both groups had increased body weight, increased blood EROD activity, decreased plasma retinol levels, and increased plasma total thyroid hormone levels. The Ah-responsive group also had increased hepatic pentoxyresorufin-O-deethylase activity, increased livercytochrome P-450 activity, and increased liver weight 12... 

Radiation is carcinogenic. The frequency of death from cancer of the thyroid, breast, lung, esophagus, stomach, and bladder was higher in Japanese survivors of the atomic bomb than in nonexposed individuals, and carcinogenesis seems to be the primary latent effect of ionizing radiation. The minimal latent period of most cancers was <15 years and depended on an individual s age at exposure and site of cancer. The relation of radiation-induced cancers to low doses and the shape of the dose-response curve (linear or nonlinear), the existence of a threshold, and the influence of dose rate and exposure period have to be determined (Hobbs and McClellan 1986). 

The therapeutic objectives for hyperthyroidism are to normalize the production of thyroid hormone minimize symptoms and long-term consequences and provide individualized therapy based on the type and severity of disease, patient age and gender, existence of nonthyroidal conditions, and response to previous therapy. 

Endocrine Thyroid gland atrophies with age Increased incidence of diabetes mellitus, thyroid disease Menopause... 

A recent report by the National Institutes of Health estimated that at 14 to 22 million people in the United States are affected by an autoimmune disease.1 As a group, these diseases represent a leading cause of death among women under age 65, with systemic lupus erythematosus, multiple sclerosis, and type 1 diabetes being the major sources of this impact on mortality.2 The autoimmune thyroid diseases, type 1 diabetes and rheumatoid arthritis are the most common of the autoimmune diseases (Table 25.1).3-5 Most autoimmune diseases disproportionately affect women. In the thyroid diseases, primary biliary cirrhosis, scleroderma, systemic lupus erythematosus, and Sjogren s syndrome, more than 85% of patients are female, but it is not known why the female predominance is so high in these specific diseases. 

Hyperthyroidism is a fairly common complaint which may occur at any age, but affects mainly females. There are several causes of increased thyroid hormone secretion but only rarely is the condition due to non-thyroidal (e.g. pituitary) illness. 

Crump C, Michaud P, Tellez R, Reyes C, Gonzalez G, Montgomery EL, Crump KS, Lobo G, Becerra C, Gibbs JP (2000) Does perchlorate in drinking water affect thyroid function in newborns or school-age children J Occup Environ Med 42 603-612... 

Vanderver GB (2007) Cigarette smoking and iodine as hypothyroxinemic stressors in US women of childhearing age a NHANES III analysis. Thyroid 17 741-746... 

Spontaneous thyroid tumors derived from the thyroid follicular cell occur in l%-3% of laboratory rats (adenomas and carcinomas combined in a variety of strains of rats aged 2 or more years). 

Children s Susceptibility. Neurodevelopmental delays and postnatal changes in serum thyroid hormone levels have been observed in animals following exposure of their mothers to chlorine dioxide or chlorite during gestation and/or lactation (Carlton and Smith 1985 Carlton et al. 1987 Gill et al. 2000 Mobley et al. 1990 Orme et al. 1985 Taylor and Pfohl 1985 Toth et al. 1990). It is not known whether age-related differences in toxicokinetic parameters exist for chlorine dioxide or chlorite. Additional studies should be designed to further examine neurodevelopmental toxicity and underlying mechanisms. 

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