ENDOTHELIN EXCRETION IN HYPERTENSIVE PREGNANCY - RELATIONSHIP TO GLOMERULAR-FILTRATION RATE, BLOOD-PRESSURE, AND SODIUM-EXCRETION

The objective of this study was to determine whether urinary endotheli n (ET) excretion is altered in pregnant women with preeclampsia or ess ential hypertension compared with normal pregnant and nonpregnant wome n, and whether urinary ET excretion is significantly related to glomer ular filtration rate (GER), blood pressure, or sodium excretion in hyp ertensive pregnant women. Subjects included 85 hypertensive women in t heir third trimester (32 with severe preeclampsia, 37 with mild preecl ampsia some of whom may be classified as having ''transient (gestatio nal) hypertension'' by other classifications, and 16 with essential h ypertension), 42 normal third-trimester pregnant women, and 26 normal nonpregnant women. Twenty-four-hour urine ET and creatinine excretion were measured in all women. ET was extracted from urine and measured b y radioimmunoassay. Plasma creatinine, serum uric acid and albumin con centrations, and urine protein and sodium excretion were also measured . Twenty-four-hour ET excretion was significantly higher (P < .01) in normal pregnant women (14.7 9.1 to 20.1 pmol/day; median interquart ile range) than in nonpregnant women (8.4 6.4 to 15.2 pmol/day) and was reduced significantly (P < .01) in hypertensive pregnant women (s evere preeclampsia: 9.0 5.5 to 12.4 pmol/day; mild preeclampsia: 7.2 5.7 to 9.9 pmol/day; essential hypertension: 7.5 6.4 to 9.4 pmol/ day) compared to values for normal pregnant women. Twenty-four-hour ur ine ET excretion in hypertensive pregnant women was correlated positiv ely but weakly with both creatinine clearance (r = 0.31, P < .01) and urine sodium excretion (r = 0.34, P < .01). Urinary ET excretion is in creased in normal pregnancy and reduced from these values in pregnanci es complicated by preeclampsia or essential hypertension. This may be explained partly by reduced filtered ET but must also reflect impaired renal ET production. There is no evidence for enhanced renal ET produ ction in preeclampsia.