Chronic Kidney Disease

Chronic kidney disease (CKD) means that the kidneys are not working as well as they once did. Various conditions can cause CKD. Severity can vary but most cases are mild or moderate, occur in older people, do not cause symptoms and do not progress to kidney failure. People with any stage of CKD have an increased risk of developing heart disease or a stroke. This is why it is important to detect even mild CKD. Treatment may not only slow down the progression of the disease, but also reduce the risk of developing heart disease or stroke.
Understanding the kidneys and urine

The two kidneys lie to the sides of the upper part of the abdomen, behind the intestines, and either side of the spine.
A large artery – the renal artery – takes blood to each kidney. The artery divides into many tiny blood vessels (capillaries) throughout the kidney. In the outer part of the kidneys, tiny blood vessels cluster together to form structures called glomeruli.
Each glomerulus is like a filter. The structure of the glomerulus allows waste products and some water and salt to pass from the blood into a tiny channel called a tubule. The liquid that remains at the end of each tubule is called urine. The urine then passes down a tube called a ureter which goes from each kidney to the bladder. Urine is stored in the bladder until it is passed out.
The main functions of the kidneys are to:
• Filter out waste products from the bloodstream, to be passed out in the urine.
• Help control blood pressure – partly by the amount of water passed out of the body as urine and partly by making hormones involved in blood pressure control.
• Make a hormone called erythropoietin, which stimulates the bone marrow to make red blood cells. This is needed to prevent anaemia.
• Help keep various salts and chemicals in the blood at the right level.
What is chronic kidney disease (CKD)?
CKD means that your kidneys are diseased or damaged in some way, or are ageing. So, the various functions of the kidney, as described in the previous section, can be affected. A whole range of conditions can cause CKD.
How is chronic kidney disease (CKD) diagnosed?
A simple blood test can estimate the volume of blood that is filtered by the tiny filters (glomeruli) in your kidneys over a given period of time. This test is called the estimated glomerular filtration rate (eGFR). A normal eGFR is 90 ml/minute/1.73 m or more. If some of the glomeruli do not filter as much as normal, then the kidney is said to have reduced or impaired kidney function.
The eGFR test involves a blood test which measures a chemical called creatinine. Creatinine is a breakdown product of muscle. Creatinine is normally cleared from the blood by the kidneys. If your kidneys are not working so well and the glomeruli are not filtering as much blood as normal, the level of creatinine in the blood goes up.
The eGFR is calculated from your age, sex and blood creatinine level.
CKD is diagnosed by the eGFR and other factors, and is divided into stages ranging thorough mild, moderate, severe and end stage renal disease.
Who has the eGFR test?
The eGFR blood test is commonly done as a routine part of monitoring people with kidney diseases or with conditions that can affect the kidneys, such as diabetes or high blood pressure. It is also often done as a routine test in many medical situations. If you are found to have CKD then the eGFR test is usually done at regular intervals to monitor your kidney function.
How common is chronic kidney disease (CKD)?
About 1 in 10 people have some degree of CKD. It can develop at any age and various conditions can lead to CKD. It becomes more common with increasing age and is more common in women.
Although about half of people aged 75 or more have some degree of CKD, most of these people do not actually have diseases of their kidneys; they have normal ageing of their kidneys.
What causes chronic kidney disease (CKD)?
A number of conditions can cause permanent damage to the kidneys and/or affect the function of the kidneys and lead to CKD. Three most common causes are:
• Diabetes. Diabetic kidney disease is a common complication of diabetes.
• High blood pressure. Untreated or poorly treated high blood pressure is a major cause of CKD. However, CKD can also cause high blood pressure, as the kidney has a role in blood pressure regulation.
• Ageing kidneys. There appears to be an age-related decline in kidney function. About half of people aged 75 or more have some degree of CKD. In most of these cases, the CKD does not progress beyond the moderate stage unless other problems of the kidney develop, such as diabetic kidney disease.
Other less common conditions that can cause CKD include:
• Diseases of the tiny filters (glomeruli), such as inflammation of the glomeruli in the kidneys (glomerulonephritis).
• Narrowing of the artery taking blood to the kidney (renal artery stenosis)
• Polycystic kidney disease.
• Blockages to the flow of urine, and repeated kidney infections.
What are the symptoms of chronic kidney disease (CKD)?
You are unlikely to feel unwell or have symptoms with mild-to-moderate CKD – (However, there may be symptoms of an underlying condition such as kidney pain with certain kidney conditions.) CKD is usually diagnosed by the estimated glomerular filtration rate (eGFR) test before any symptoms develop.
Symptoms tend to develop when CKD becomes very severe. The symptoms at first tend to be vague and nonspecific, such as feeling tired, having less energy than usual, and just not feeling well. With more severe CKD, symptoms that may develop include:
• Difficulty thinking clearly.
• A poor appetite.
• Weight loss.
• Dry, itchy skin.
• Muscle cramps.
• Fluid retention which causes swollen feet and ankles.
• Puffiness around the eyes.
• A need to pass urine more often than usual.
• Being pale due to anaemia.
• Feeling sick.
If the kidney function is very severely reduced then various other problems may develop – for example, anaemia and an imbalance of calcium, phosphate and other chemicals in the bloodstream. End-stage kidney failure is eventually fatal unless treated.
Further diagnostic tests
Routine urine dipstick tests from time to time to check for blood and protein in the urine may be carried out. Also, blood tests may be done from time to time to check on your blood level of chemicals such as sodium, potassium, calcium and phosphate. The need for other tests then depends on various factors and the doctor will advise. For example:
• An ultrasound scan of the kidneys or a kidney biopsy may be advised if certain kidney conditions are suspected.
• If the CKD progresses to moderately to severely reduced then various other tests may be done. For example, blood tests to check for anaemia and an altered level of parathyroid hormone (PTH). PTH is involved in the control of the blood level of calcium and phosphate.
What is the treatment for chronic kidney disease (CKD)?
Research studies have shown that, in many people, treatment at early stages of CKD can prevent or slow down progression through to eventual kidney failure.
The aims of treatment include:
• If possible, to treat any underlying kidney condition.
• To prevent or slow down the progression of CKD.
• To reduce the risk of developing cardiovascular disease (CVD).
• To relieve symptoms and problems caused by CKD.
Treating any underlying kidney condition
There are various conditions that can cause CKD. For some of these there may be specific treatments for that particular condition – for example:
• Good blood sugar (glucose) control for people with diabetes.
• Blood pressure control for people with high blood pressure.
• Antibiotic medication for people with recurring kidney infections.
• Surgery for people with a blockage to urine flow.
Preventing or slowing down the progression of CKD
Once CKD has developed, in many cases it tends gradually to become worse over months or years. This can occur even if an underlying cause has been treated. Treatment to prevent or slow down the progression of CKD includes:
• Blood pressure control. The most important treatment to prevent or delay the progression of CKD, whatever the underlying cause, is to keep blood pressure well controlled. Most people with CKD will require medication to control their blood pressure. The target blood pressure level to aim is usually below 130/80 mm Hg, and even lower in some circumstances.
• Review of medication. Certain medicines can affect the kidneys as a side-effect which can make CKD worse. For example, if you have CKD you should not take anti-inflammatory medicines unless advised to by a doctor. You may also need to adjust the dose of certain medicines that you may take if your CKD gets worse.
Reducing the risk of developing CVD
People with CKD have an increased risk of developing cardiovascular diseases, such as heart disease, stroke, and peripheral arterial disease. People with CKD are actually twenty times more likely to die from cardiovascular-related problems than from kidney failure. This is why reducing any other cardiovascular risk factors is so important.
• Good control of blood pressure (and blood glucose level if you have diabetes).
• Medication to lower your cholesterol level (called statins), which is often given to people with CKD.
• Where relevant, to tackle lifestyle risk factors. This means to:
o Stop smoking if the patient smokes and stop alcohol is the patients drinks alcohol.
o Eat a healthy diet which includes a low salt intake.
o Keep weight and waist in check.
o Take regular physical activity.
Relieving symptoms and problems caused by CKD
If CKD becomes severe treatment may be needed to combat various problems caused by the poor kidney function. For example:
• Anaemia may develop which may need treatment with iron or erythropoietin – a hormone normally made by the kidneys.
• Abnormal levels of calcium or phosphate in the blood may need treatment.
• How much fluid to drink, and how much salt to take needs to be determined.
• Other dietary advice may be given which can help to control factors such as the level of calcium and potassium in the body.
If end-stage kidney failure develops, the patient is likely to need kidney dialysis or a kidney transplant to survive.
What is the outlook (prognosis)?
Stages mild-to-moderate CKD are common, with most cases occurring in older people. It tends to become gradually worse over months or years. However, the rate of progression varies from case to case, and often depends on the severity of any underlying condition. However, in most cases, CKD progresses only very slowly. Only a small number of people with CKD progress to end-stage kidney failure.

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