Look after your kidneys

Most of us have two of them. They're the most commonly transplanted organ, but we're more likely to think of them in the context of a traditional British steak pie. What are they? Your kidneys, of course. Looking after them is easy if you just know how.

What do your kidneys do?

Your kidneys have several vital functions. They filter out waste products and toxins from your bloodstream; make a hormone that helps prevent anaemia; keep salts in the blood in balance; and help control blood pressure.

What happens when they stop working properly?

If your kidneys suddenly start working much less efficiently, you'll go into acute kidney failure - uncommon but potentially fatal if not treated promptly. Far more common (up to one in 10 people are affected) is chronic kidney disease, or CKD, which comes on gradually, over months or years.

Am I at risk?

The older you get, the more likely you are to be affected - about half of people over 75 have CKD. Diabetes and high blood pressure also increase your risk of CKD. That's why if you have either of these conditions, your doctor will want to monitor your kidney function and blood pressure at least every year.

Why does it matter?

As well as being caused by uncontrolled high blood pressure, having CKD raises your blood pressure - and this in turn increases your risk of stroke and heart attack. That's why, if you have CKD, your doctor will give you medication to control your blood pressure. If CKD progresses far enough, your kidneys can stop working completely. Fortunately for most people with CKD, careful blood pressure control and using certain preventive medicines can slow this progression enough for your kidneys to last you a lifetime.

How is CKD diagnosed?

You can be almost completely confident you don't have CKD if your blood pressure is normal without taking blood pressure medicine. CKD is diagnosed by a test called eGFR (if you really want to know, the 'proper' longwinded medical name is estimated glomerular filtration rate). If your eGFR is above 60, your doctor won't worry unless you have other signs of damage to your kidneys such as protein in your urine. An eGFR of 30-59 is 'moderate' CKD and below 30 is 'severe'.

This blood test is done routinely for anyone with diabetes or high blood pressure. If you're found to have CKD on blood testing, your doctor will want to check your urine and do some other blood tests to see what the cause might be. There's usually no obvious cause found - unless you consider getting older a 'cause'!

When is CKD not CKD?

There's some debate about whether we should call the levels of eGFR so commonly found in older people 'disease'. 'Disease' usually means something abnormal, or likely to cause you harm. As you get older, your kidneys gradually get less efficient at filtering - but this only gets to be a problem if it reaches very low levels, sometimes called 'end- stage kidney disease', when your eGFR is below 15. A rapid drop in eGFR is often a cause for serious concern to a doctor, as it suggests your kidneys are struggling. An eGFR of 50 in an eighty year old, which has taken five years to drop from 55, is technically classed as 'moderate CKD'. In fact, at that rate, your kidneys are only going to give out if you live to 120!

How is CKD treated?

The mainstays of treatment of CKD are:

  • Keeping your blood pressure tightly controlled, ideally to a level of about 130/80
  • Taking medicine from one of two 'families' called the ACE inhibitors or the ARBs. Both groups work to lower blood pressure, but they have an extra protective effect on the kidneys
  • Keeping other risk factors for heart attack or stroke (such as cholesterol) under control.

Living with a single kidney

Tens of thousands of people in the UK live perfectly healthy lives with only one kidney. About one in 750 people are born with only one, and others have a kidney removed because of blockage, injury or tumour. Fortunately, your one kidney will increase in size to take on the extra work. However, you should take extra precautions to protect the one you've got:

  • Avoid injury - some contact sports like rugby or martial arts increase the risk of damage to your kidney, which is more vulnerable because of its size
  • Keep up the fluids - your kidney filters toxins from your bloodstream, and lack of fluid makes you prone to infections or stones in the kidney. Drink at least 1 ½-2 litres of non -alcoholic fluid a day
  • Check it out! - get your kidney function checked regularly (say, once a year) with a blood test, a urine test for protein and a blood pressure check.

Artificial kidneys on the horizon?

In the last few years, scientists have been working to bring together nanotechnology and the latest advances in cellular biology for patients with end-stage kidney failure. At present, the only options are a kidney dialysis or a kidney transplant - they're both literally lifesavers, but neither is an easy option. Dialysis involves being attached to a machine for four hours, three times a week. There is a serious shortage of kidneys for transplant in the UK, and you'll need a lifelong cocktail of drugs to suppress your immune system and stop your body rejecting the kidney. An artificial kidney should largely get round both problems. But don't hold your breath - clinical trials aren't due to start until 2017.



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