THE FILTRATION RATE, EFFECTIVE RENAL BLOOD FLOW, TUBULAR EXCRETORY MASS AND PHENOL RED CLEARANCE IN SPECIFIC TOXEMIA OF PREGANANCY 1

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Abstract
Renal function in patients with specific toxemia of pregnancy was detd., using the inulin clearance as a measure of glomerular filtration rate, the diodrast clearance as a measure of effective renal blood flow, and the diodrast Tm as a measure of tubular excretory mass. 13 patients were studied in 14 pregnancies. Tests were done late in pregnancy and again after delivery. The antepartum observations in about one half of these patients fall within the normal range. However, when antepartum figures are compared to postpartum figures for a given individual, as well as when the toxemic subjects are considered as a group in comparison to the normals, certain trends which appear to be characteristic of toxemia of pregnancy are evident. During toxemia the glomerular filtration rate is normal or slightly diminished, the effective renal blood flow is normal or above normal, and the filtration fraction (inulin/diodrast clearance ratio) is normal or low. The finding of a normal effective renal blood flow or actual renal hyperemia in the presence of arterial hypertension is of particular interest since renal ischemia of varying degree associated with a high filtration fraction, indicating efferent arteriolar hypertonus, is characteristic of essential hypertension. Following delivery, the filtration fraction is seen to increase, in part because of an increased glomerular filtration rate, and in part because of a diminished effective renal blood flow. In the patients with clinical cure, the postpartum observations fall within normal limits. In the patients with residual hypertension the filtration fraction is high and the effective renal blood flow low postpartum. The renal ischemia seen after delivery in this latter group is like that seen in patients with essential hypertension.