After every surgery, I sit down and go through that day’s blood results, matching each one to the patient it belongs to. Most are normal. Some mean a phone call. A few are so alarming the lab rings us before I’ve even opened my laptop.

But there is one result that comes up again and again, for a condition most of my patients have never heard of, because it rarely causes any symptoms at all.

And I’m worried that there are countless patients across the country who do not realise they have this disease either.

Take Linda, who I spoke to last week. She has high blood pressure and takes medication for it, so has annual blood tests.

One of those tests checks kidney function, and combined with a urine test, it revealed she had something called chronic kidney disease.

Her first questions were: ‘What does that even mean? And is it serious?’

Chronic kidney disease, or CKD, affects one in ten adults in Britain – around 7.2million of us. Every year it contributes to an estimated 45,000 deaths – that’s more than the number of breast and prostate cancer deaths combined.

And yet the vast majority walk around with no idea they have it.

That is because CKD does not behave like other serious diseases. Think of it less as a single illness and more as a risk factor.

The kidneys essentially clean the blood – removing waste and excess water to make urine. But for those with CKD, the kidneys slowly stop functioning properly, meaning they remove less waste and water.

If symptoms of the condition do appear, they tend to be vague at first – tiredness, most commonly, as well as brain fog and itchy skin

The kidneys essentially clean the blood – removing waste and excess water to make urine. But for those with CKD, the kidneys slowly stop functioning properly, meaning they remove less

Eventually, the kidneys can give out completely – known as kidney failure – meaning dialysis (blood cleaning treatment) or an organ transplant will be needed.

Thankfully, however, this only affects around 2 per cent of CKD patients.

Instead the real danger, even when the disease is mild, is the extra strain it puts on the heart and blood vessels.

People with CKD are around 20 times more likely to die of a heart attack or stroke than they are to ever reach kidney failure.

Like Linda, most people with CKD have no symptoms at all in the early stages, because the body compensates so well for a decline in kidney function.

That is exactly why most cases are only picked up by chance, when a blood or urine test is done for something else entirely.

If symptoms do appear, they tend to be vague at first – tiredness, most commonly, as well as brain fog and itchy skin.

Later on you may notice weight loss, swollen ankles, feet or hands, breathlessness, blood in your urine, needing to urinate more often or muscle cramps.

By the time you notice any of this, the disease has often been present for years.

And, unlike many other diseases, there is no reversing CKD. It cannot be cured and the damage cannot be healed.

GP, author and broadcaster Dr Philippa Kaye

So what causes CKD?

CKD is closely tied to diabetes, high blood pressure – and the relationship runs both ways.

Diabetes and high blood pressure damage the kidneys, but damaged kidneys also increase blood sugar (the symptom of diabetes) and push blood pressure up.

Both conditions are typically triggered by poor lifestyle – namely an unhealthy diet, a lack of exercise and excessive drinking and smoking.

For most patients, the only way to get diagnosed is via two simple tests that a GP can order.

One is a blood test that measures for creatinine, a waste product the kidneys should be clearing, and is used to calculate how well the organs are working.

The other is a urine test that looks for something called albumin, a protein that leaks into the urine when the kidneys are damaged.

Anyone with diabetes or high blood pressure should ask their GP for these tests.

Early diagnosis of CKD is crucial because, while it cannot be reversed, it can be halted.

Getting blood pressure down and diabetes under control are crucial. This can be done by losing weight if you need to, eating a balanced diet – one that is rich in fruit, vegetables and wholegrains – but low in salt and sugar.

Staying active matters enormously too. Exercise cuts your risk of heart disease, and CKD is fundamentally a heart problem in disguise.

If you smoke, quit, and keep alcohol under 14 units a week – ideally well under.

However, alongside these lifestyle changes, there are also effective medicines.

A decade ago, there were few drugs that could help CKD patients.

But there has been a genuine breakthrough in recent years: a class of medicines called SGLT2 inhibitors – the most well-known called dapagliflozin and empagliflozin.

Originally developed for diabetes, they have been shown in major trials to significantly slow the decline in kidney function and cut the risk of heart failure and death in people with CKD whether or not they have diabetes.

Any CKD patient who hasn’t been offered one of these tablets should speak to their GP about the possibility of taking them.

There are many more Lindas out there who don’t yet know they have this disease. If you’re aged 40 to 74 with no other health conditions, you’re entitled to an NHS health check every five years, covering blood pressure, blood glucose and cholesterol – and if your blood pressure is raised, your kidney function too.

Don’t leave it until it’s too late and you begin to show symptoms – or even have a heart attack. Get checked now.