New urine test spots pre-eclampsia 10 weeks earlier than current versions

Pregnant women have a new test for a deadly complication which affects 50,000 people a year. A simple urine test could detect pre-eclampsia up to 10 weeks earlier, according to doctors in the United States (US).

Currently, the complication affecting one in 12 pregnancies first comes to light at antenatal appointments. High blood pressure and protein in the urine are the first warning signs of pre-eclampsia, which threatens the life of a baby in the womb when it is rejected by the mother’s immune system.

But the new test picks up an earlier and more subtle red flag in the body – fragments of kidney cells in the urine. Researchers say these show up well before proteins or high blood pressure, at 27 weeks of pregnancy, so that a woman can be taken into hospital and closely monitored immediately.

Pre-eclampsia occurs when a mother’s white blood cells fail to adapt to her baby, which is treated as a foreign body. Women, most at risk of pre-eclampsia if they are overweight or over 40, can also die.

Doctors have historically tested women’s urine for proteins, and taken their blood pressure, to diagnose the condition. But previous US research has found fragments of kidney cells appear less than seven months into a pregnancy. Garovic said these can be detected eight to 10 weeks earlier than the usual symptoms doctors check for.

Indeed, women who develop pre-eclampsia might never develop high blood pressure or urine proteins, which makes the new test far more accurate. While previous versions have been time-consuming and expensive, the researchers say theirs takes just two rather than 24 hours and is several times cheaper.

The findings, in a study of 84 pregnant women, of which half had pre-eclampsia, are published in the Journal of the American Society of Nephrology. They also show a blood test can be used to diagnose pre-eclampsia, which in addition to kidney damage appears to cause a surge of foetal haemoglobin – the main oxygen transport protein in an unborn baby.

It is hoped the findings showing the changes in the body caused by pre-eclampsia will provide new treatments for the condition.