There are a number of tests involved in diagnosing kidney failure:
- Blood tests are used to find out how much of the waste substances are being filtered out;
- Urine is tested to see if it contains blood, protein, glucose, ketones, bilirubin, bacteria crystals and casts. Urinanalysis is important in detecting
early kidney disease. The American National Kidney Foundation states that this type of
urinalysis "should be part of routine physical examinations for everyone";
- Scans are taken using either magnetic resonance imaging (MRI), computerised tomography (CT) or ultrasound to see if any unusual blockages
can be identified. When kidney disease is advanced, the kidneys are shrunken and have an uneven shape;
- A kidney biopsy which involves taking a tissue sample from the kidney in order to examine it for damage. A kidney biopsy is useful in indicating a
specific disease process and whether it may respond to treatment. Biopsies are also used to find out why a kidney transplant may not be doing well
The glomerular filtration rate (GFR) and the stages of chronic kidney disease.
The glomerular filtration rate is a measure of kidney function. It is arrived at by looking at blood creatinine test results, weight, body size,
age and gender. The rate itself is a measure of how many millilitres of wate products the kidneys can filter in a minute and is used to indicate how far
the disease has progresses. A healthy pair of kidneys should be able to filter more than 90ml per minute.
The phases of chronic kidney disease have been categorised into 5 distinct stages;
- stage one- the GFR is normal but other evidence of kidney disease is present;
- stage two- a GFR of less than ninety, with other evidence of kidney disease;
- stage three (a)- a GFR of less than 60 with, or without, other evidence of kidney damage;
- stage three (b)- a GFR of less than 45 with, or without, other evidence of kidney damage;
- stage four- a GFR of less than 30 with,or without, other evidence of kidney damage;
- stage five- a GFR of less than 15- established renal failure has occurred;
NICE recommended the division of stage three into two separate stages in 2008.
The 2008 NICE guidance on chronic kidney disease recommends that people with any of the following should be offered testing for CKD:
- diabetes;
- hypertension;
- cardiovascular disease;
- structural renal tract disease;
- multisystem diseases with potential kidney involvement e.g. systemic lupus erythmatosus (lupus);
- a family history of stage 5 CKD or hereditary kidney disease;
- opportunistic detection of harmaturia or proteinuria.
In testing for chronic kidney disease it is recommended that doctors obtain a minimum of three GFR estimations over a period of three months.
Disease progression is defined as a decline of 5 over 1 year or a decline of 10 over 5years.
