Standards of Metabolism
These basal metabolism tests are valuable chiefly because of their aid in the recognition of diseases in which the metabolic rates are increased or decreased and in the differential diag- nosis between abnormal conditions having similar manifestations yet regularly having different metabolic rates; also as a guide in treatment, and to determine the effectiveness of the treatment. Especially in the following conditions the tests are of value:
Enlarged thyroid gland with symptoms of hyperthyroid-ism; enlarged thyroid where symptoms resembling those of hyperthyroidism are due to other causes; enlarged thyroid with no symptoms; symptoms of hyperthyroidism with no enlargement of the thyroid; enlargement of the thyroid from tumors; enlarged thyroid with symptoms of hypothyroidism; symptoms of hypothyroidism with no change in the size of the thyroid.
In the case of goiter with disturbed health the tests will help determine whether the health impairment is due to the goiter or to other causes. Among conditions of disturbed thyroid activity in which the tests are of value may be men¬tioned nervous heart afflictions, nervousness, weakness, defec¬tive circulation, loss of weight and inability to gain weight, incipient tuberculosis and gastrointestinal disorders.
Usually in determining the basal metabolic rate comparison of the findings in a given case is made with tests already made on normal persons of both sexes and various ages. The rate of an individual subject is expressed in terms of per¬centage of the normal: a 25 per cent, increase being termed a basal metabolic rate of +25, and a 25 per cent, decrease being termed a basal metabolic rate of —25. There being a range in normal individuals of 15 per cent, above and below normal, only values above +15 or below —15 are considered abnormal.
Numerous conditions have been listed in which basal metabolic rate determination is of diagnostic value. Accord¬ing to one medical work, the value “is greatest in the group of cases with one or more of the symptoms caused by hyper¬thyroidism. Cardiac disturbances, as tachycardia, cardiac myasthenia (muscular weakness of the heart), and palpita¬tion; fine tremors, general debility, loss of weight, anemia, attacks of vomiting and diarrhea, psychic disturbance, as depressions and irritability, psychasthenia and sweats are symptoms in respect of which the exclusion of thyroid dis¬turbance or its acceptance as cause can be made by a determi¬nation of basal metabolism.” The test was further considered useful “in the differential diagnosis of hysteria, neurasthenia, tuberculosis (incipient), and neuroses simulating thyroid disease, and necessary in the diagnosis of effort syndrome.”