Abstract
Metabolism experiments were performed on 7 adult male albino rats, first under normal conditions and then under conditions of hyperthyroidism induced by dosage with iodinated casein. The basal metabolism of energy and the output in the urine of nitrogen from endogenous sources only were determined under both normal and hyperthyroid conditions by the usual methods. Both the basal metabolism and the minimum endogenous nitrogen metabolism are elevated 80 to 90% during hyperthyroidism of the intensity induced. The percentage of total creatinine of the total endogenous urinary nitrogen is not greatly disturbed, although a marked creatinuria is induced. The similar effect of thyroid-active material on the basal metabolism and on the minimum endogenous metabolism of nitrogen in the adult animal is in harmony with the Terroine-Smuts principle that the two are related causally and, under normal conditions, vary with body size in a parallel fashion, other determining factors remaining the same.