ALBUMIN EXCRETORY RATE IN NORMAL AND HYPERTENSIVE PREGNANCY

1. The purpose of this study was to determine whether the 24 h urinary albumin excretory rate was increased in the third trimester of normal pregnancy or in pregnant women with hypertension who had 24 h urinary total protein excretion within the normal range. 2. Twenty-four hour urinary creatinine and albumin excretions were determined prospectivel y in 26 nonpregnant and 115 pregnant women in their third trimester (4 0 in normal pregnancy, 38 with mild preeclampsia, 20 with severe pre-e clampsia, 17 with essential hypertension) in whom urinary total protei n excretion was normal. Both the urinary albumin excretion rate and th e urinary albumin/creatinine ratio were compared among the groups. The clearance of albumin relative to that of creatinine was also calculat ed in the hypertensive women and in 14 of the non-pregnant women and n ine of the normal pregnant women. 3. The twenty-four hour urinary albu min excretion Fate was similar in non-pregnant [8(5-10) mg/day; median (interquartile range)] and normal pregnant [7(6-10) mg/day] women. Wo men with essential hypertension [6(4-16) mg/day] and mild preeclampsia [7(4-10) mg/day] had a urinary albumin excretion rate similar to that of normal pregnant women. Women with severe pre-eclampsia had an urin ary albumin excretion rate increased [13(7-32) mg/day] compared with o ther groups (P<0.05). The clearance of albumin relative to that of cre atinine was elevated significantly only in women with severe pre-eclam psia compared with normal pregnant women (0.00054 versus 0.00012; P<0. 05). Blood pressures were similar among all hypertensive groups. The u pper limit of the urinary albumin excretion rate was 20 mg/day in norm al pregnant women, similar to that in non-pregnant women. 4. Urinary a lbumin excretion is unchanged in the third trimester of normal pregnan cy, but is increased in women with features of severe pre-eclampsia wh o have normal total urinary protein excretion. This is not fully expla ined by a reduction in glomerular filtration rate nor by different sys temic blood pressures, and probably reflects enhanced glomerular capil lary permeability, possibly with altered maximum renal tubular reabsor ption capacity for albumin.