Chronic Kidney Disease
What does it mean to have CKD?
Chronic kidney disease (CKD) is a condition in which the kidneys don't work as well as they should persistently for at least three months. By looking at your pathology and imaging results, we measure and grade the severity of kidney disease by:
1. Estimated glomerular filtration rate (eGFR) – A blood test. You can think of this as the approximate percentage kidney function remaining. This diminishes with increased age. For instance, the average 80 year old has an eGFR of around 50mL/min/1.73m2. That is, they have around 50% of kidney function remaining.
2. Protein (or albumin) to creatinine ratio – A urine test. As the kidneys become damaged, they leak protein. The more protein leaks in the urine, the more severe the kidney disease is.
3. Blood or white blood cells in the urine – Healthy kidneys do not leak these cells into urine
Depending on our clinic interview, we may suggest further blood tests, and possibly a kidney biopsy. This procedure is done under local anaesthetic to sample the kidney tissue. This allows us to have a better idea of what the underlying problem is, how severe it is, and how to treat it.
How did I get CKD?
In order, most common causes in Australia for CKD are:
1. Diabetes
2. Glomerulonephritis – Resulting from inflammation and damage to the filtering units (called glomeruli) in the kidney
3. High blood pressure
4. Polycystic kidney disease – Usually an inherited condition where the kidneys grow multiple cysts, which eventually replace the kidney tissue
5. Reflux nephropathy – A condition where the urine flows back from the bladder into the kidney, rather that out of the body.
Age is a major risk factor for CKD - increasing age increases. However, older people are often at lower risk for progression to end-stage kidney disease (ESKD). Other factors that are associated (but don’t necessarily cause) increased risk of end stage kidney disease include male sex, race (especially Indigenous Australians), low socioeconomic status, and other medical issues such as high blood pressure and smoking.
How will CKD affect my daily life?
Chronic kidney disease (CKD) usually doesn't cause symptoms until it's in the advanced stages, and it's often discovered through routine blood testing. The symptoms of CKD are not specific and can include difficulty sleeping, frequent need to urinate at night, a metallic taste in the mouth, fatigue, muscle cramps and twitches, restless legs, lack of appetite, abdominal pain, nausea, vomiting, and weight loss, and itching. If severe, it can cause shortness of breath and seizures
As the CKD progresses, a person may need to have more medical check-ups, make changes to their medications and lifestyle in order to slow down the progression of the disease and manage symptoms.
What are the treatment options for CKD?
The treatment options for CKD are aimed at slowing down the progression of the disease and managing symptoms. One of the main goals is to reduce the amount of protein in the urine, which is a strong predictor of kidney function decline. This can be done by controlling blood pressure, taking medications that block the renin-angiotensin system (ideally ACE inhibitors), SGLT2 inhibitors, beta-blockers and aldosterone antagonist therapy. Additionally, alkali therapy (such as sodium bicarbonate, sodium citrate, or a diet high in fruits and vegetables) may also be recommended to slow CKD progression and prevent cardiovascular disease. Your kidney specialist can tailor the options to you.
Ideally we would like to slow the GFR decline to around 1mL/min/year (around 1% decrease in kidney function per year). This is the natural rate of decline of a person’s kidneys.
What can I do to maintain my kidney function?
There are several things that can you can do to maintain kidney function even if you have chronic kidney disease. Much of this comes down to diet and lifestyle. This includes managing obesity, diabetes, cholesterol levels, and high blood pressure. Smoking should be avoided as it promotes progression of all forms of kidney disease.
One of the most important things is to limit the intake of salt, as high intake has been linked to CKD progression and an increased risk for cardiovascular disease. It is recommended to have a sodium intake of about 2-3 grams per day (around one teaspoon a day). Beware of hidden sources of salt, especially in processed food or takeaway. The average Australian (according to South Australia Health) eats 9 grams of salt per day!
High fructose intake (found in table sugar, Fanta, Sprite, Coca-Cola and Pepsi) should also be avoided.
Protein intake should also be considered. Too much protein has been linked to an increased risk of end stage kidney disease. A moderate amount of protein a day of 0.7 grams per kilogram of ideal body weight (you can find this by looking up your height) per day has been associated with less kidney function decline and less protein in the urine. For scale, a 100g steak has around 30g of protein in it. Meat is also high in phosphorus. As CKD progresses, it becomes important to control these levels. This can be achieved by reducing meat and dairy products and substituting them with plant-based proteins.
Your kidney specialist will be able to link you in with a dietician who can juggle the complexities of each individual.
Nonsteroidal anti-inflammatory drugs should be avoided or minimised. Two common anti-inflammatories are ibuprofen (also called Brufen, Nurofen, Advil) and diclofenac (also called Voltaren). This becomes especially important in those who are also have heart and liver conditions, and are on ACE inhibitors and diuretics.
What is the progression of CKD?
As our age increases, the kidney function will gradually decline around 1 mL/min/1.73m2 each year (or 1% a year).
In clinic, we measure CKD by regularly monitoring kidney function and amount of protein in the urine. Ideally, we would target a protein leak from the kidneys of less than 500mg each day (normal being 100mg/d).
Decline in renal function can be caused by a variety of factors, including the activity of the primary kidney disease, natural progression, age and co-existing medical conditions. For instance, primary membranous nephropathy is relatively slow to progress (around 3 mL/min/1.73m2 or 3% per year) compared with IgA nephropathy which can progress as quickly as 9 mL/min/1.73m2 (or 9% per year) at protein levels in the urine of 3000-5000mg/d. . Factors such as obesity, hypertension, hyperlipidemia, or hyperglycemia can also contribute to the progression of CKD.
Will I need dialysis or a kidney transplant?
As your kidney function deteriorates, you may eventually reach a point where you require renal replacement therapy (RRT) such as haemodialysis, peritoneal dialysis or a kidney transplant. Your healthcare team (including your kidney specialist and dialysis nurses) will work with you to determine the best option for you, and to ensure that you have the necessary education and support.
Usually, I start having these conversations with my patients when their GFR drops to less than 20 mL/min/1.73m2 (ie 20% of kidney function) to give us time to plan for the next steps. For instance, if haemodialysis is chosen, you may need to have an arteriovenous fistula (a connection between an artery and vein) constructed, which can take a couple of months to heal. Similarly, if peritoneal dialysis is chosen, you may need to have a peritoneal dialysis catheter inserted in advance (ideally 6 weeks before starting dialysis in order for the abdominal wound to heal).
Renal replacement therapy usually starts around a GFR of 5-8mL/min/1.73m2 (5-8% of kidney function), or if you have symptoms of kidney failure (which can start even around 20 mL/min/1.73m2 ).
Early kidney transplantation may be associated with better outcomes, so if you're a suitable candidate, you may be placed on the transplant waiting list.
On the other hand, if you're nearing end stage of kidney disease and are not interested in or suitable for dialysis or transplantation, you may choose to receive palliative management. This focuses on symptom relief and maintaining your quality of life.
How will end stage kidney disease affect my overall health and longevity?
End stage kidney disease comes with other complications.
On dialysis, survival rates are quite variable. They are naturally lower in older age groups. Survival is especially dependent on complications such as heart attacks and infections.
Anaemia (low blood count) is common in those especially with advanced CKD. This is because of a deficiency in the blood stimulating hormone erythropoietin (which is normally produced by the kidneys), low iron and chronic body inflammation.
The bones are also affected due to high phosphate and low vitamin D levels (which is usually activated by the kidneys). This causes the bones to be reabsorbed, with the minerals deposited in the blood vessels. This is a key factor which makes our patients more prone to heart attacks, strokes and other vascular diseases.
Infections are also very dangerous for those with end stage kidney failure. This is because CKD induces a state of immunosuppression. This makes the body’s immune system less effective.
The good news is that there are solutions to the above challenges. We can artificially replace erythropoetin, we have medications to fortify the bones, and our patients are encouraged to keep up with their vaccinations (eg influenza, pneumococcal, hepatitis). It is therefore important to regularly keep in touch with your healthcare team!
Sources:
Australia & New Zealand Dialysis & Transplant Registry
Johnson Richard J John Feehally and Floege Jürgen. 2019. Comprehensive Clinical Nephrology (version Sixth edition) Sixth ed. Edinburgh: Elsevier. http://www.engineeringvillage.com/controller/servlet/OpenURL?genre=book&isbn=9780323479097>.
