The Cerebral Circulation and Metabolism in Hyperthyroidism and Myxedema1

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Abstract
Cerebral hemodynamic and metabolic studies by the nitrous oxide technique were made in 22 subjects with hyperthyroidism and 11 subjects with myxedema; post-treatment euthyroid values served as controls. Hyperthyroidism was associated with a 42% increase in central blood flow (CBF), a 35% decrease in central vascular resistance (CVR) and a 7% decrease in mean arterial blood pressure (MABP); these circulatory changes were not accompanied by changes in cerebral O2 utilization. Myxedema was associated with a 22% reduction in CBF, a 48% increase in CVR, and a 16% increase in MABP; again, the circulatory changes were not associated with changes in the rate of cerebral O2 utilization. The cerebral circulation thus shares equally in the general circulatory changes incident to alterations in thyroid function but cerebral O2 and glucose consumption is unaffected by such alterations.