Kidney disease is any disease or condition that affects the function of the kidneys, which is to filter and remove wastes and water from the bloodstream.
Most people have two kidneys and they are located near the middle of your back, just under the ribcage. Each kidney weighs about 150g, and is about the size of an adult fist. They are bean-shaped and reddish brown in colour.
- Diabetes and untreated high blood pressure are two of the commonest causes of chronic kidney disease (CKD)
- If you are Maori or Pacific and have diabetes, you are at increased risk of kidney disease - see your doctor regularly
- Excellent blood pressure and blood sugar control reduces the complications of diabetes
- Early detection and treatment of kidney disease is important as it can prevent or slow the progression of kidney disease
- Chronic kidney disease is a silent condition (no pain or obvious symptoms) so risk factors (such as diabetes and high blood pressure) need to be checked for regularly
The kidneys have four main roles in the body:
- Remove waste from the body. Nutrients that cannot be used by the body become toxic. The kidneys filter the blood to remove them from the body in the urine
- Remove excess water from the body
- Make and regulate important hormones in the body. These hormones control red blood cell production, blood pressure regulation and calcium absorption
- Control body chemistry by regulating the amount of salt, water and other chemicals circulating in the body.
Various diseases can affect kidney function. These include:
- high blood pressure
- hereditary disease of the kidneys
- scarring of the kidneys (due to backflow of urine from the bladder)
- urinary tract infections, eg. bladder infections
- kidney damage as a side effect of medication, particularly painkillers and in the past, headache powders.
- Cancer of the kidneys
Kidney disease often causes no symptoms at all. It is not uncommon for people to lose up to 70% of their kidney function before developing any symptoms.
The first signs may be general and can include:
- changes in frequency and quantity of urine passed, especially at night
- pain or burning when passing urine
- blood in the urine
- puffiness or swelling around the eyes and ankles
Many of the causes of kidney failure strike at random, and cannot be predicted or prevented. Others, such as diabetes, are present for many years before they develop into kidney failure. When this is so, there is an opportunity for early diagnosis and prevention of progression of kidney failure to end stage.
Recent advances in our understanding has created a great deal of interest in the possibility of picking up kidney failure early and offering preventative treatment before the kidneys are completely destroyed. These early detection and prevention programmes are particularly targeted at high risk groups such as those who have diabetes, high blood pressure, a family history of kidney disease or other predisposing factors.
If you or a member of your family fall into these groups, you should talk to your local doctor about being tested for kidney problems and find out what you can do to keep them healthy and functioning well.
There are several tests that can detect kidney disease such as:
- Blood tests: these measure blood levels of creatinine and urea. Both of these products are normally excreted in the urine, but if the kidneys are not functioning properly, increased amounts can be detected in the blood.
- Urine tests: the presence of protein in the urine, simply diagnosed with a dipstick test, can often be a marker for silent kidney disease.
- Renal imaging: involves taking a picture of the kidney using a variety of methods, such as ultrasound, CAT scan or magnetic resonance imaging. These tests help determine if there are any unusual growths or blockages to the flow or urine.
- Renal biopsy: a hospital procedure in which a needle is inserted through the skin into the kidney. A small sample of kidney tissue is removed for microscopic examination.
When kidney disease is detected early, changes to lifestyle and diet can slow the disease and prevent serious consequences.
There are also specific medications available that can slow or prevent the progression of kidney failure.
The treatment you will need depends on what stage of kidney disease you have and what caused it in the first place. In brief:
- Stages 1 to 3 (early to moderate kidney failure) - reduce blood pressure, keep diabetes well controlled and take medication to reduce further damage to your kidneys.
- Stage 3 - glomerular filtration rate (GFR) less than 60 - also referral to a nephrologist (kidney specialist)
- Stages 4 to 5 - dialysis, renal transplantation or supportive measures are generally needed.
You can look after the health of your kidneys by following these points:
- have your blood pressure checked at least once a year
- have your blood sugar checked for diabetes
- don't smoke - there is no safe level of smoking and it damages blood vessel walls
- check your cholesterol levels (high cholesterol damages blood vessels in the kidney)
- maintain your weight within a healthy range for your height with a well-balanced diet - regular exercise will also help control your weight
- have an annual check-up with a GP. If you need a blood test, ask for your kidney function to be checked. Ask for your urine to be checked for blood, protein and sugar.
Note: Herbal supplements can be risky for people with kidney disease
- Often considered harmless, the regular use of herbal products may result in harm for people with kidney disease
- Very few herbs have been studied in people with kidney disease
- The government does not regulate herbal supplements so the exact content is unknown
- Purity, safety and effectiveness of the products are unknown
- Some herbal supplements are contaminated with toxic heavy metals such as lead or mercury
- Some products may contain minerals that are harmful to people with kidney disease
- Some Chinese herbs containing aristolochic acid (AA) used for weight loss have caused kidney injury and resulted in kidney failure. Despite warnings from government authorities herbal remedies containing AA are still available via the internet
- Some herbs interact with prescription drugs e.g. St John’s wort, echinacea, ginseng
- Many herbs can be toxic to the kidneys e.g. alfalfa, dandelion, aloe, cat's claw, juniper berry
- Self medication involves risk. Patients should be asked about this when they present to their GP.