The effect of pregnancy on kidney function in renal allograft recipients

Abstract

In women with renal transplants glomerular filtration rate (GFR) increases during pregnancy but how soon the increment occurs, its relation to pre-pregnancy GFR, and the overall pattern of change are unknown. Twenty-four hour creatinine clearance (24-hr CCr) were measured prospectively in ten pregnancies in eight allograft recipients before conception, throughout pregnancy, 8 to 12 weeks postpartum, and 4 to 6 monthly thereafter. Inulin (CIn) in creatinine (CCr) clearances during infusion were also determined and protein excretion was evaluated. The results were compared to those in similar studies in ten healthy women. By the tenth gestational week 24-hr CCr was 124 +/- (SD) 15.9 ml/min in healthy women (an increase of 38%; range, 18 to 69%) and in transplant patients was 105 +/- 28.1 ml/min (an increase of 34%: range, 10 to 60%), with the greatest increments in those whose allografts functioned best before conception, regardless of donor source and sex or the transplant-pregnancy interval. In late pregnancy mean 24-hr CCr decreased by 19% (range, 6 to 28%) in healthy women and by 34% (range, 12 to 57%) in the transplant patients, but in most this did not represent graft deterioration nor lead to permanent impairment. At all time points CIn values were 5 to 10% greater than those for 24-hr CCr but slightly less than infusion CCr values. Protein excretion increased throughout pregnancy and by the third trimester in healthy women averaged 200 mg in 24 hr and regularly exceeded 500 mg in 24 hr in transplant patients, which was three times non-pregnant levels and probably not clinically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Overview of Pregnancy in Renal Transplant Patients

“…Davison reported that the increase in 24-hour creatinine clearance in healthy women was comparable to allograft recipients at 10 weeks of gestation (38% versus 34%). Allograft recipients also have a higher 24-hour protein excretion as compared to healthy women which increases throughout pregnancy, becomes threefold higher by third trimester regularly exceeding 500 mg (versus 200 mg in healthy women), and returns to prepregnancy levels at 3 months postpartum [15]. Proteinuria in pregnancy should never be attributed to normal pregnancy related changes and common comorbidities like urinary tract infection and preeclampsia should be ruled out.…”

Clinical Therapeutics in Pregnancy

“…An early change in pregnancy is systemic vasodilation which is thought to be mediated by progesterone and relaxin [8, 70]. Dilation of renal vasculature with an increase in glomerular filtration rate (GFR) and effective renal plasma flow (RPF) also occurs [71].…”

Caring for the pregnant kidney transplant recipient

“…Normal pregnancy-related hyperfiltration occurs in transplants with the greatest increase in glomerular filtration rate (GFR) occurring in patients whose allografts functioned best before conception (17,36). GFR usually decreases and returns to baseline toward the end of pregnancy or the postpartum period.…”

“…Short-term effects of hyperfiltration can be seen in proteinuria which can appear or increase to abnormal levels in the last three months of pregnancy but usually returns to baseline within three months postpartum. The presence of proteinuria early in the pregnancy is a marker of previous renal damage which, when combined with maternal hypertension, puts a patient at risk for an unfavorable renal outcome (36).…”