INDEX hormones, stimulating

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 plasma concentration of calcidiol is the most sensitive and usefiil index of vitamin D status, and is correlated with elevated plasma parathyroid hormone and alkaline phosphatase activity (Table 3.4). As shown in Table 3.2, the reference range of plasma calcidiol is between 20 to 150 nmol per L, with a twofold seasonal variation in temperate regions. Concentrations below 20 nmol per L are considered to indicate impending deficiency, and osteomalacia is seen in adults when plasma calcidiol falls below 10 nmol per L. In children, clinical signs of rickets are seen when plasma calcidiol faUs below 20 nmol per L. The plasma concentration of calcitriol does not give a useful indication of vitamin D status. The reference range is between 38 to 144 pmol per L and is maintained because of the stimulation of calcidiol 1-hydroxylation by parathyroid hormone secreted in response to faUing concentrations of calcium (Holick, 1990). 

Physical inactivity and elevated body mass index (BMI), independent of level of physical activity, are associated with an elevated risk of colon adenoma, colon cancer, and rectal cancer. Individuals with a total higher level of activity throughout life have the lowest risk. Hypotheses for these relationships include the observation that physical activity stimulates bowel peristalsis, resulting in decreased bowel transit time, and the possibihty that exercise-induced alterations in body glucose, insuhn levels, and perhaps other hormones may reduce tumor ceU growth. ... 

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