Chronic kidney disease (CKD) affects around 1 in 10 people in the UK. Here, we’ll explore its causes, risk factors, symptoms and treatments. To understand CKD, it helps to first understand what your kidneys do.
The role of your kidneys
Your kidneys are 2 bean-shaped organs located in your lower back area that have a rich blood supply. They are responsible for cleaning your blood of toxins and waste products, and making sure substances such as water and electrolytes in your blood remain at the right levels.
They are also responsible for maintaining your blood pressure and producing or activating certain hormones, specifically erythropoietin and the hormone vitamin D. Erythropoietin encourages your bone marrow to make red blood cells. Vitamin D is largely inactive in your blood until it’s activated by the kidneys to stimulate your body to take up calcium from your food. This means your kidneys are needed for both your blood and bone health.
Chronic kidney disease (CKD) is different from acute kidney injury (AKI). Acute injury to your kidneys occurs suddenly (in days) and is usually short-term. What’s more, damage from acute kidney injury can often be reversed with prompt treatment and time to heal.
In contrast, CKD occurs when your kidneys are damaged over a prolonged period of time (at least several months). The resulting damage is irreversible as kidney tissue becomes scarred.
The 5 stages of CKD
CKD is divided into 5 stages based on the levels of a waste product that builds up in the blood called creatinine. Healthy kidneys efficiently remove creatinine, resulting in low levels in the blood, while unhealthy kidneys are less able to do this, resulting in higher levels.
To assess kidney function, first, creatinine levels are measured. This measurement is then put into a formula called the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) (2009) equation. This formula also considers your age and sex.
The formula produces a number that represents your kidney function and is used to identify to what stage your kidney disease has progressed. The lower the number, the worse your kidney function and the greater the severity of your CKD. The 5 stages are as follows:
- Stage 1 — kidney function greater than 90; your kidneys work as well as normal, but you still have other signs of kidney damage, such as protein in your urine and structural abnormalities of your kidneys
- Stage 2 — kidney function between 60 and 90; your kidneys function well most of the time, but you have signs of kidney damage
- Stage 3 — kidney function between 30 and 60; your kidneys are not working well, and this is affecting other aspects of your health, such as your blood pressure, bone health and energy levels
- Stage 4 — kidney function between 15 and 30; your kidneys are severely damaged, and this is affecting multiple aspects of your health
- Stage 5 — kidney function less than 15; your kidneys have failed or are very close to failing, and you will need dialysis to remove some of the toxins from your blood and/or a kidney transplant
With early diagnosis and prompt treatment, it’s possible to slow down the progression of CKD and reduce the chances of complications, such as heart disease, heart attacks, stroke and peripheral artery disease. However, most chronic damage caused is usually irreversible.
Causes of CKD
In the UK, the most common causes of CKD are high blood pressure (hypertension) and diabetes. Both of these conditions can develop for months or years without any obvious symptoms and silently damage your kidneys.
Other causes of CKD include autoimmune diseases that attack the kidneys, such as autoimmune glomerulonephritis and vasculitis, and inherited conditions that cause the kidneys to develop cysts and become deformed, such as autosomal dominant polycystic kidney disease (ADPKD).
If you have a blockage (obstruction) at some point along your urinary system that is not resolved, over time, this can damage your kidneys and lead to CKD. For example, an enlarged prostate squashing the urethra (the tube that urine leaves the body through) or kidney stones stuck in the ureter (the tube that urine passes from the kidneys to the bladder through).
Frequent urinary tract infections (UTIs) and drug abuse, including medications such as ibuprofen and naproxen, can also lead to CKD.
Risk factors for CKD
If you have undiagnosed or poorly controlled high blood pressure or diabetes, you are at high risk of CKD.
You are also at high risk if you have an autoimmune disease that affects your kidneys, a history of kidney disease or an inherited kidney disease.
Lifestyle factors that increase your risk include smoking, recreational drug use, overuse of painkillers such as ibuprofen and naproxen, and regularly not drinking enough fluids to stay well-hydrated.
Symptoms and diagnosis of CKD
CKD is often diagnosed incidentally when having a blood test to investigate other symptoms or as part of a routine health check.
If your blood test results suggest that you have early-stage CKD, you may not need to see a specialist as your GP can provide appropriate treatment and advice. If you have later stages of CKD, you will be referred to a specialist called a nephrologist.
In some cases, your GP may recommend a blood test to check your kidney function due to symptoms such as:
- Anaemia — symptoms include fatigue, breathlessness, palpitations and paler skin
- Fatigue
- Frothy urine — a sign of protein in your urine
- Reduced appetite
- Swelling due to fluid retention (oedema)
CKD treatments
To treat CKD effectively, it’s important to first identify the cause. For example, if you are suspected of having an autoimmune or inherited kidney condition, you may need a kidney biopsy and/or genetic testing to confirm this.
Once the underlying cause has been identified, your doctor will recommend the most appropriate treatment. This will often include lifestyle changes to reduce the burden placed on your kidneys, such as drinking more water, losing any excess weight, quitting smoking and reducing the amount of salt in your diet.
If you have diabetes or high blood pressure, you will be advised to get these conditions under control with appropriate treatment and the support of your doctor. This may involve getting advice about your diet, fluid intake and lifestyle.
Medications for CKD
If lifestyle changes and better management of other diseases contributing to your CKD are not enough, your doctor may recommend medications that lower the pressure in your kidneys to reduce damage.
If you have polycystic kidney disease, your doctor may prescribe a special type of diuretic medication, that is, medication that reduces the build-up of water in your body — they are commonly called water tablets.
If you have an autoimmune condition that is damaging your kidneys, your doctor may recommend immunosuppressant medication.
In later stages of CKD, when anaemia develops, you may also be given medication to raise your haemoglobin levels by encouraging the production of more red blood cells.
If your bone health is reduced due to CKD, your doctor may prescribe activated vitamin D supplements and medications to reduce bone breakdown.
In the final stage of CKD, your doctor will discuss your options for dialysis and a kidney transplant, which will depend on your health and circumstances. If you are healthy enough to have a kidney transplant, you will likely still need to have dialysis while you wait for a donor kidney to become available.
How to reduce your risk of CKD
The most effective way to reduce your risk of CKD is to lead a healthy lifestyle. This includes not smoking, following a healthy, balanced diet and exercising regularly. If you develop conditions that are known risk factors for CKD, such as diabetes and high blood pressure, it’s important to take your medication as prescribed and follow the advice of your doctor.
