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Sometimes even people with serious kidney disease have no symptoms. That is why a blood or urine test is necessary to check for kidney problems.

There are two key tests used to detect kidney damage and to assess how well your kidneys are functioning at removing toxins and waste products from your blood.

Blood test

A blood test is used to measure your serum creatinine level which helps to indicate how well the kidneys are filtering the blood. Creatinine is a waste product made from muscle use and the breakdown of the protein you eat. As the blood creatinine rises, kidney function decreases. Decreased kidney function means that your kidneys are not able to remove the toxins and waste products from your blood as well as someone with normal kidney function.

The estimate (or percentage) of kidney function is called the glomerular filtration rate (GFR) or estimated glomerular filtration rate (eGFR). Glomeruli are tiny blood vessels in the kidney that help to filter waste. The GFR is a way of measuring how well the kidneys are working by determining the rate at which the glomeruli are filtering waste products from your blood. The eGFR is the most common way to measure kidney function at kidney clinics.


Simple laboratory tests such as urinalysis (a urine dipstick), which looks for blood and a protein called albumin in the urine, are also useful in detecting kidney damage at an early stage and determining your risk of losing more kidney function. The filters of the kidney do not normally allow protein in the urine so if protein (albumin) is detected, it is a sign that the filters of the kidney are being damaged. The more albumin that you have in your urine, the greater the risk of losing kidney function over time. Other blood tests, X-rays, kidney ultrasound or a kidney biopsy may also be needed to diagnose the specific type of kidney disease and to determine the appropriate treatment.

Signs and symptoms of kidney disease

If your kidney function continues to decline, you may start developing symptoms of kidney disease. Each person is different, but most people will start to develop uremia as the kidneys fail and are unable to remove wastes from the body. There are many symptoms of uremia that occur as kidney function declines, including:

Weight loss
Loss of appetite
Shortness of breath
Leg cramps
Chest pain
Easy bruising
Swelling in ankles and legs
Bad taste in the mouth
Restless legs
Difficulty sleeping
Cold intolerance
Skin colour changes
Decreased sexual desire


Are You At Risk?
Did you know that 1 in 10 Canadians has kidney disease? Take 10 minutes to answer these 10 questions. The answers will help you know if you should talk to your doctor about having your kidney function checked.