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Protein in the urine can signal that a patient is up to
twice as likely to develop heart disease.
Source: iStockphoto

We already rely on urine to tell us when we’re dehydrated or our kidneys are struggling, but the diagnostic equivalent of liquid gold could soon enable doctors to more accurately predict who’s at risk of developing cardiovascular disease (CVD) – and help them to avoid it.

Doctors currently rely on a range of factors, including high blood pressure and cholesterol, to identify patients who are at risk of having a heart attack. Although these measures provide a lot of information, CVD is still responsible for the most deaths in Australia and kills around seven million people each year worldwide, so there’s plenty of room for improvement. Researchers at the George Institute for International Health in Sydney have proved that the presence of protein in urine, which usually signals kidney disease, can indicate that someone is up to twice as likely to develop CVD and should be monitored as part of risk assessment for heart attack. 

Dr Vlado Perkovic, the lead author of the study, believes that urine screening could save lives by helping doctors identify people that are more likely to develop heart problems.  On its own, no indicator can predict whether or not someone will definitely have a heart attack, but when examined altogether, factors such as protein in the urine, cholesterol, diabetes and blood pressure, can paint a comprehensive picture of who’s at risk. Doctors currently use models to estimate how likely a patient is to have a heart attack in the next five years, but none of the most commonly used designs take into account protein in the urine, according to Perkovic. “By incorporating urine screening into the models we may be able to much more accurately predict who will and who won’t have a heart attack”. Of course this then gives doctors time to reduce their patient’s risk, through lifestyle changes or medication, and could not only save lives but reduce the $ 5.4 billion CVD costs the Australian government each year.

The beauty of the urine test is that it’s quick, cheap and painless (unless it burns when you pee, but that’s a whole other problem). Basic testing for protein in the urine could be done with a dipstick on the spot in your doctor’s office or even in a mobile screening caravan.

It might seem strange that something happening in your heart can affect what comes out of your bladder, and the researchers still aren’t certain what causes this relationship. Scientists have suspected for just over a decade that there was a link, but it was initially thought that the presence of protein in the urine was an indirect marker of some other heart attack inducer, such as high blood pressure, which can actually cause kidney disease.

But Perkovic and his team examined studies that had already taken into account diabetes, blood pressure and cholesterol to see whether there was still a relationship between protein in the urine and heart disease – and there was. Because they analysed a wide range of previous research, the team ended up looking at results from almost 170,000 people and could prove for the first time just how strongly urine tests can predict CVD. They found that people don’t necessarily need to have kidney disease to have an increased risk, as even small amounts of protein in the urine can signal that a patient is up to 50 per cent more likely to have a heart attack.

Perkovic and his team are now looking into whether or not the markers can also signal an increased risk of stroke. Preliminary findings suggest that they do, in which case the humble urine test could save even more lives.