Urea-Kidney Test

UREA

Question 1. What is Blood area nitrogen or urea?

Urea is a waste product formed in the liver when protein is broken down or metabolized. Urea is released into the blood is carried to the kidneys, where it is filtered out of the blood and released into the urine. Since this is an ongoing process, there is usually a small but stable amount of urea nitrogen in the blood. However, when the kidneys cannot filter wastes out of the blood due to disease or damage, then the level of urea in the blood will rise.

Question 2. When do we test by Urea Measurement?

Blood urea level measured to detect kidney disease and is part of kidney function test that includes creatinine and electrolytes, often called UEC or Urea, electrolyte & creatinine test.

The following conditions require urea or kidney function test:

All very sick patients

General health screen

Suspect kidney disease

Monitor kidney disease

Monitor effectiveness of dialysis

Monitor drug treatment

Prior to major operation

Question 3. What is type of Blood sample use?

A simple blood sample is collected on plain tube to get plasma or serum which can be used for kidney function test along with creatinine, electrolytes and other tests.

Question 4. How good is urea in detecting kidney disease?

Urea is increased when 60 % of kidney function is affected. Hence, in early stages when kidney function is still less than 60% affected urea level may still be normal. This also applies to creatinine level too.

Question 5. Any cause false elevation?

False elevation of urea is seen in dehydration, high protein meal prior to test and use of wrong reference ranges in elderly and children. Low urea is seen in patient with severe liver disease, starvation or protein deficiency and over-hydration.

Questions 6. When do I have kidney test done?

You should have kidney test done;

As baseline health check

Symptoms suggest kidney disease

                                Loin pain

                                Blood in urine,

                                Pain urinating

Have high blood pressure

Have family history of kidney diseases

Take cancer medications

Take antibiotics for many weeks

Vomiting repeatedly

Chronic diarrhoea

Question 7. Is there anything else I should know?

Almost always urea is requested as part of kidney function tests and should be interpreted together with creatinine report and electrolytes. Interpretation is not straight forward and in all cases doctors will assess urea result with clinical information and other test reports available.

Question 8. Is BUN/Creatinine ratio useful?

Occasionally, your doctor may use urea: creatinine ratio to see if the sign of impaired kidney function (high urea and creatinine) is due to dehydration or kidney disease. Normally, the ratio is between 10:1 and 20:1.  Increased ratio, ie, urea proportionally higher than creatinine is observed in dehydration or decreased blood supply to kidneys as in heart failure. This implies that the high urea and creatinine, also called azotaemia is not due to kidney disease but lack of blood flow to kidneys. If this isn’t corrected quickly by increased fluid intake or infusion, kidney damage can occur.