Diagnosis of Kidney Failure :

• First, the kidney disease is suspected, when any of the following is present :
• The symptoms of kidney disease (described earlier).High blood pressure, particularly in the young (less than 35 years of age).Abnormal urine examination even when he/she has no symptoms. This is usually detected when one requires a routine urine examination as part of health check-up before taking a new job. Once kidney failure is suspected, following basic tests are done to determine the nature of kidney disease and extent of kidney failure :

Routine urine examination :

A normal urine should not show any protein (albumin) or blood in the urine. Presence of this is abnormal and requires further tests. However, a normal urine does not rule out a kidney disease.
 
24 hour urine for albumin :

If the routine urine examination shows protein (albumin) in the urine, it is necessary to quantitate protein loss in the 24 hours urine sample.

Blood tests :

This is done to check for the amount of waste products (BUN and creatinine) accumulated in the blood because of poor kidney function. Other substances in the blood normally controlled by the kidneys are also checked. The degree of rise in BUN and creatinine gives a rough idea of the degree of kidney failure but does not indicate the nature of kidney disease.
 
Ultrasound :

This simple test is useful in determining the size of the kidneys. When kidneys are found to be small by this test it usually signifies an irreversible kidney disease. This test is also useful when obstruction to the flow of urine is suspected.

I.V.P. ( Intravenous pyelography ) :

In this test, a dye is injected into a vein and then the X-ray pictures of the kidney are obtained . This test is commonly asked when kidney stone is suspected. An IVP cannot be done when the kidney failure is far advanced. In such a case, ultrasound is a better test.
 
Hereditary Kidney Diseases :

This test involves taking a piece of kidney tissue and examining under microscope to determine the nature of kidney disease which helps in deciding the treatment. For the test one has to get admitted to hospital. For the procedure, he/she will be asked to lie on the stomach and kidney to be biopsied will be localized with the help of ultrasound. The biopsy site will then be numbed with a local anaesthetic. Then the kidney biopsy needle will be inserted into the kidney and 2-3 small pieces of kidney tissue obtained. After biopsy, he/she will be asked to remain in bed for 24 hours

Source  : Narmada Kidney Foundation : Link : http://www.narmadakidney.org/INDEX.ASP?PAGE=DIAGNOSIS