Early prediction of pre-eclampsia by measurement of kallikrein and creatinine on a random urine sample.

OBJECTIVE

To assess the measurement of inactive urinary kallikrein (IUK) to creatinine (Cr) ratio (IUK:Cr) on an untimed urine sample, collected between 16 and 20 weeks of pregnancy, as a predictive test for the development of both proteinuric and nonproteinuric pre-eclampsia.

DESIGN

A prospective longitudinal study.

SETTING

A clinic for antenatal care and a university research department.

PARTICIPANTS

Three hundred and seven normotensive women randomly selected (124 nulliparous and 183 parous) attending the antenatal clinic for their booking visit.

MAIN OUTCOME MEASURES: 1. Nonproteinuric pre-eclampsia: a rise in diastolic blood pressure of 25 mmHg or more and a crossing of the threshold of 90 mmHg; 2. Proteinuric pre-eclampsia: same as 1. plus the development of significant proteinuria ( > 1 + on urine dipstick).

RESULTS

Thirty-seven women developed pre-eclampsia, 12 of whom had proteinuria. Median IUK:Cr ratio in this group was 78.27, compared with 358.19 in the remainder. Analysis of receiver-operator characteristics gave an area under the curve of 0.803. An IUK:Cr ratio of 170 or less in this study predicted nonproteinuric or proteinuric pre-eclampsia with a sensitivity of 70% and a specificity of 86%. Ten of the twelve women who had proteinuria had an IUK:Cr below 170. Median IUK:Cr for those with proteinuric pre-eclampsia was 72.91.

CONCLUSIONS

Measurement of IUK:Cr on a urine sample, collected between 16 and 20 weeks of gestation, represents a simple and practical test for the risk of subsequent pre-eclampsia, with a sensitivity and specificity comparable to those reported by other investigators using the widely recognised, but less practical, angiotensin II sensitivity test.