Kidney disease is a term used by doctors to include any abnormality of the kidneys, even if there is only very slight damage. ‘Chronic’ means a condition that does not get completely better. Some people think that ‘chronic’ means severe. This is not the case, and often CKD is only a very slight abnormality in the kidneys.
Recent research suggests that 1 in 10 of the population may have CKD, but it is less common in young adults, being present in 1 in 50 people. In those aged over 75 years, CKD is present in 1 out of 2 people. However, many of the elderly people with CKD may not have ‘diseased’ kidneys, but have normal ageing of their kidneys. Although severe kidney failure will not occur with normal ageing of the kidneys, there is an increased chance of high blood pressure and heart disease or stroke, so that medical checks will be helpful.
In most cases CKD does not cause any symptoms, and is detected because tests are abnormal. These may be urine tests for blood or protein; an X-ray or scan of the kidneys; or a blood test to measure kidney function.
There are many causes of CKD, and two of the commonest causes are high blood pressure and ageing of the kidneys. Very few of the causes of CKD are completely curable, so it is often not necessary to do extensive tests to find a cause, so long as blood tests show the kidney function is stable. If someone has markedly reduced kidney function, declining kidney function, or associated problems such as kidney pain, a scan of the kidneys will be performed. Some people will also have tests such as a cystoscopy (flexible tube to look inside the bladder), or a kidney biopsy (a small piece of kidney is removed with a needle and looked at under the microscope).
A test called the eGFR (estimated glomerular filtration rate) is used to measure kidney function. The eGFR is calculated by the laboratory from the level of a chemical called creatinine in the blood.
A normal eGFR is about 100 ml/min in young adults, so the eGFR is sometimes referred to as the percentage of normal kidney function, as the number is the same.
Some young adults with normal kidneys will have an eGFR as low as 75 ml/min, and this falls by about 1 ml/min per year as people get older, so many healthy people aged 75 will have an eGFR of 50-60 ml/min.
Most laboratories now report eGFR alongside their measurements of blood creatinine levels and this is the most reliable way to obtain an eGFR result. It is possible to use on-line calculator (e.g. at the Renal Association’s website - www.renal.org/eGFRcalc/GFR.pl) by putting in age, sex, blood level of creatinine and racial origin. However, different laboratories use different methods to measure serum creatinine, and each of these methods gives slightly different answers. The eGFR that the laboratory reports takes account of these differences, but the on-line calculators do not; so the results that they give are not quite as accurate.
CKD is divided into 5 stages:-
Leakage of protein into the urine increases the risk of any kidney disease. Everyone with CKD should therefore have a urine test to measure the amount of protein in the urine, and if this level is high, they will receive more careful treatment and possibly more extensive investigations. More Details
There are some things that everyone with CKD should try to do. These are:-
The blood pressure should be treated carefully. If it is above 140/85, tablets are usually needed, and the aim is to get the blood pressure down to 130/80 or lower. The cholesterol should be checked, and some people will be advised to take a daily aspirin tablet. A blood test to check eGFR should be performed once a year. If the urine tests show a lot of protein in the urine, or the kidney function is declining over time, the case will be discussed with a kidney specialist, or a referral may be made to a kidney specialist.
Treatment as in CKD stages 1 and 2, but with more careful monitoring for declining kidney function.
Treatment as for CKD stages 1-3. Additionally, any medications should be reviewed, as the dose may need to be altered and some drugs may need to be avoided as they could damage the kidneys further. This should include prescribed drugs and any drugs bought at the chemist and complementary therapies. In CKD stages 4 and 5 it is usually necessary to get advice from a kidney specialist, especially in stage 5 because kidney failure may become life threatening.
If someone with CKD also has diabetes, extra care to control the blood pressure, blood sugar levels and cholesterol levels is required. More intensive monitoring will be performed, including extra urine tests to look for protein in the urine. This is because CKD can be a complication of diabetes. However, CKD does not cause diabetes.
In people with declining kidney function, a treatment plan should be made with a kidney specialist team well before CKD stage 5 is reached. There are also several books and other aids that give information and help make a decision about the best treatment, some of which are available from the National Kidney Federation (for a FREE copy of Help I’ve got Kidney Failure by Dr Rob Higgins, phone the NKF Helpline on 0845 601 02 09 [Local charge within the UK]).
Most people with CKD should be able to lead normal lives. CKD does not normally run in families and routine family screening is not necessary if one person is affected. However, some specific types of kidney disease do run in families, and people should check with their health care team to see if testing of family members is needed.
NKF Controlled Document No. 60, Chronic Kidney Disease (CKD), written 21 July 2006. Last reviewed 29 November 2012.
The National Kidney Federation cannot accept responsibility for information provided. The above is for guidance only. Patients are advised to seek further information from their own doctor.