Changes in heart size and plasma volume during fasting

Heart size as determined by standard 6 foot x-rays of the chest before and after fasting was performed on 21 patients. Plasma volume by means of measurement of apparent volume of distribution of albumen tagged with I 131 was measured in 7 of these patients. The findings indicated that the heart size decreased in all patients studied and that a significant decrease in plasma volume was found during fasting in each subject. No correlation was found between change in heart size or blood volume and amount of weight loss or duration of fasting. All subjects were ambulatory and changes were not related to bed rest. The findings were related to the saluresis of fasting.