MECHANISM OF DIURESIS: ALTERATIONS IN THE SPECIFIC GRAVITY OF THE BLOOD PLASMA WITH ONSET OF DIURESIS IN HEART FAILURE

Abstract

In a study of the mechanism of diuresis, change in level of the sp. gr. of the plasma was used as a measure of change in blood vol., decrease in sp. gr. indicating dilution of the blood, and increase in sp. gr. conc. Blood sp. gr. was estimated by the method of Moore and Van Slyke. Diuresis in the presence of heart failure of the congestive type depended on changes initiated in the tissues since it was accompanied by decrease in plasma sp. gr. that is by dilution of the circulating blood indicating increase in blood vol. Dilution of the blood preceded the onset of diuresis and increase in blood vol. was probably the stimulus that initiated diuretic response of the kidneys. The results were similar not only when diuresis occurred spontaneously, but when it was occasioned by digitalis, and by theocalcin, and moreover whether in presence of normal sinus rhythm or of auricular fibrillation, and whether the cause of the heart disease was rheumatic fever, syphilis, arteriosclerosis or hypertension. These studies do not relate to the anatomical portions of the kidney which take part in the accelerated formation of urine in diuresis. The sp. gr. of the plasma must fall from a high level to 1.0255 or lower for the initiation of diuresis. Below this level may be called the diuretic zone in heart failure, in that it corresponds to a dilution of the blood with increase in blood vol. of sufficient magnitude to initiate diuresis. In uncomplicated heart disease the level of sp. gr. of the plasma, and by inference the plasma proteins, from previous work of Moore and Van Slyke and Moore and Stewart, is in the normal range not only before the onset of failure but during and after recovery from failure. Plasma protein deficiency does not participate in the etiology of cardiac edema usually. In the technique of taking blood for plasma or serum proteins or sp. gr. of the plasma, samples should not be obtained when diuresis is being initiated or occurring, since low results may be recorded which do not reflect the usual level for the subject.