PP036. The intrarenal renin-angiotensin system and pregnancy outcome

The intrarenal renin angiotensin system (iRAS) may be activated in normal pregnancy. Failure of activation may predispose to preeclampsia.

Urinary angiotensinogen/creatinine (uAGT/creat), albumin and protein/creat were measured in 10 non-pregnant and 17 pregnant non-Indigenous women and 61 Indigenous pregnant women (in whom other components of iRAS were also measured).

uAGT/creat was higher in pregnancy (18.2±3.2μg/mmol, n=9 vs. 1.1±0.3μg/mmol, P=0.001, n=10). Women with clinical proteinuria and/or preeclampsia had low uAGT/creat (n=3). Hypertensive women had normal high uAGT/creat (n=4). Indigenous pregnant women had higher protein/creat (P=0.01) and lower uAGT/creat (2.9±1.0μg/mmol, P=0.010, n=51) than non-Indigenous pregnant women. Indigenous women were classified based on a uAGT/creat of <2μg/mmol (n=37) or >2.0μg/mmol (n=12). Only low uAGT/creat Indigenous pregnant women had correlations between uAGT/creat and albumin/creat (r=0.367, P=0.027), renin/creat and albumin or protein/creat (r=0.493, P=0.002, r=0.603, P<0.001). uAGT/creat levels fell with gestation (r=-0.329, P=0.047) while Cystatin C increased (r=0.592, P=0.000).

The iRAS is activated in normal pregnancy. This is not the case in women with proteinuria/preeclampsia or in many Indigenous women who have higher urinary protein/creat. Therefore a low uAGT/creat in pregnancy may indicate impaired renal function and be associated with an increased risk of preeclampsia.