Hypothyroidism 2748 INDEX

Welsh GS MMPl profiles and factors A and R. J CMn Psychol 21 43-47, 1965 Wenzel K, Meinhold H, Ruffenberg M Classification of hypothyroidism in evaluating patients after radioiodine therapy by serum cholesterol, Tj uptake, total T4, F T4 index, total Tj, basal TSH and TRH test. Fur J Chn Invest 4 141, 1974 Wernicke JF The side effect profile and safety of fluoxetine. J Chn Psychiatry 46 (3 sec 2) 59-67, 1985... 

TSH, T3, T, T3-resin uptake, free thyroxin index), but careful attention to early signs and symptoms of hypofunction (e.g., weight gain, cold intolerance, hair loss) may be more productive. Thyroid-stimulating hormone is sensitive to early thyroid changes and, if elevated, should prompt treatment with thyroid supplements to avoid goiter or hypothyroidism. 

The etiology and pathogenesis of hypothyroidism are outlined in Table 38-5. Hypothyroidism can occur with or without thyroid enlargement (goiter). The laboratory diagnosis of hypothyroidism in the adult is easily made by the combination of a low free thyroxine (or low free thyroxine index) and elevated serum TSH (Table 38-2). 

Hypothyroid women frequently have anovulatory cycles and are therefore relatively infertile until restoration of the euthyroid state. This has led to the widespread use of thyroid hormone for infertility, although there is no evidence for its usefulness in infertile euthyroid patients. In a pregnant hypothyroid patient receiving thyroxine, it is extremely important that the daily dose of thyroxine be adequate because early development of the fetal brain depends on maternal thyroxine. In many hypothyroid patients, a modest increase in the thyroxine dose (about 20-30%) is required to normalize the serum TSH level during pregnancy. Because of the elevated maternal TBG, the free thyroxine index (FT4I) or free thyroxine (FT4) and TSH (Table 38-2) must be used to monitor maternal thyroxine dosages. 

Cardiovascular Effects Thyroid hormones directly and indirectly influence cardiac function, and cardiovascular manifestations are prominent clinical consequences of thyroid disease. In hyperthyroidism, there is tachycardia, increased stroke volume, increased cardiac index, cardiac hypertrophy, decreased peripheral vascular resistance, and increased pulse pressure. In hypothyroidism, there is bradycardia, decreased cardiac index, pericardial effusion, increased peripheral vascular resistance, decreased pulse pressure, and elevation of mean arterial pressure. 

One of the most frequent questions asked has been whether or not pure ID results in hypothyroidism (Morreale de Escobar et ai, 1997). The answer to this is especially difficult, because there are few quantitative indices of thyroid hormone action in different tissues. For this reason, we have focused on concentrations of 3,5,3 -triiodo-L-thyronine (T3), which was taken as an index of possible thyroid hormone effectiveness at the individual tissue level, as discussed elsewhere (Escobar-Morreale et ai, 1995). As will be seen, the thyroid status of rats with ID cannot be defined for the animal as a whole, because it is eminently tissue specific At all grades of ID, elevated. 

In a study by Pop et al. (1999) performed in the Netherlands, a country considered to be free of ID, the developmental index of the child was correlated to the first trimester free thyroxine (FT4) levels. One out of every two women with first trimester FT4 values below the tenth percentile had a child with a developmental index more than 1 SD below the mean. None of these women were clinically or subclinically hypothyroid. 

A woman with Turner s syndrome, who had undergone a total thyroidectomy and who was being treated with levothyroxine 100 micrograms daily, had a marked fall in serum levothyroxine levels and free levothyroxine index with a dramatic rise in TSH levels when given rifampicin. However, no symptoms of clinical hypothyroidism developed, and the drop in serum levothyroxine occurred prior to starting rifampicin, which may reflect the clinicd picture of an acute infection. Another case describes a fall in TSH levels when rifampicin was discontinued. ... 

In conclusion, important progresses are taking place in the standardisation of the survey methods used in IDD evaluation. At the same time new developments such as the introduction of thyroid echography improves the reliability of goitre prevalences assessment but international norms and directives will be needed for the presentation of these new data. With borderline low iodine intake, the percentage of recalled newborns obtained in neonatal screening for neonatal hypothyroidism is a sensitive index of the severity of the iodine deficiency. In former East of Europe where the... 

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