Evaluation of Urine Nephrin:Creatinine Ratio Longitudinally in Pregnancy for the Detection of Preeclampsia and Kidney Damage in Women With Pre‐Existing Diabetes

AIMS: (i) To evaluate longitudinal changes in urine nephrin to creatinine ratio (NCR) throughout gestation in women with pre-existing diabetes; (ii) To evaluate the association of NCR with diabetic nephropathy and pregnancy outcomes including preeclampsia. METHODS: A prospective cohort study of 158 pregnant women with pre-existing diabetes was conducted. Changes in urinary nephrin, protein, albumin and creatinine were assessed serially during pregnancy at four time points. The association with diabetic nephropathy and pregnancy outcomes was investigated by linear mixed effects models. Spearman's rank correlation was used to assess the correlation of NCR with protein/albumin to creatinine ratio (PCR/ACR). RESULTS: NCR increased from early to late pregnancy (p < 0.05); however, there was no significant difference in NCR between those with and without preeclampsia irrespective of gestational age. Women with diabetic nephropathy had 3.48 times greater [1.38-8.77] NCR at 14 weeks compared to those without (p < 0.01), although this was not sustained in late pregnancy. NCR was positively associated with PCR through pregnancy (p < 0.01) and with ACR at 14 and 30 weeks (p < 0.05); however, the associations were weak. CONCLUSIONS: While all women with diabetes show a gradual increase in NCR during pregnancy, it was not a useful marker in predicting preeclampsia. However, higher NCR was indicative of kidney damage in the first trimester and could potentially be useful for monitoring diabetic nephropathy.