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BUN 24 hrs Urine Test

BUN 24 hrs Urine Test

also known as: Blood Urea Nitrogen , BUN , BUN test , Serum Urea Nitrogen Blood , Serum Urea Nitrogen , Urea Nitrogen.

Kidneys are responsible for filtering blood in the human body. The substance creatine is formed during metabolism. Creatine is then broken down into another substance called creatinine, which is taken out of your blood by the kidneys and then passed out of your body in urine, among other substances like urea nitrogen. If your kidneys are damaged and aren’t functioning normally, the amount of these wastes in your blood is high. Apart from malfunctioning kidneys, heart failure, dehydration, certain medicines, intestinal bleeding, or a diet high in protein also can increase your Blood Urea Nitrogen (BUN) level. BUN test checks your blood for sign of damaged kidneys. A creatinine clearance test is done on both a blood sample and on a sample of urine collected over 24 hours.

Collection of the blood sample: An elastic band is wrapped around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.

The needle site is cleaned with alcohol Blood is collected from the vein A gauze bad or a cotton ball is used to cover the needle site and pressure is applied to stop the bleeding Collection of the 24-hour urine sample You start collecting your urine in the morning. When you first get up, empty your bladder but do not save this urine. Write down the time that you urinated to mark the beginning of your 24-hour collection period. For the next 24 hours, collect all your urine. Your doctor or lab will usually provide you with a large container that holds about 1 gal (4 L). The container has a small amount of preservative in it. Do not touch its insides. Keep the large container in the refrigerator for the 24 hours. Empty your bladder for the final time at or just before the end of the 24-hour period. Add this urine to the large container and record the time. Ensure that the sample contains only urine and no other materials or substances

Your result will be a measure of how much BUN is in your blood. The range considered normal is between 7 to 20 milligrams per decilitre.
High creatinine blood levels can mean serious kidney damage. Kidney damage can be caused by a life-threatening infection, shock, cancer, or low blood flow to the kidneys. Low blood creatinine levels can mean lower muscle mass caused by a disease, such as muscular dystrophy, or by aging.
Apart from these, there could be several other reasons for an off-range BUN test result:
• High or low protein diets can cause high and low BUN scores respectively
• Several medications, including steroids and antibiotics
• Pregnancy and aging
• Dehydration
• Urinary tract obstruction

Do not do any strenuous exercise for 48 hours before having creatinine tests. Do not eat more than 227 g of meat, or proteins for 24 hours before the blood creatinine test and during the creatinine clearance urine test. Be sure to drink enough fluids during the 24-hour urine collection but do not drink coffee and tea, since they can cause your body to pass more urine.

Uremia is best evaluated with creatinine as well as urea nitrogen.In both prerenal and postrenal azotemia, for instance, BUN is apt to be increased somewhat more than is creatinine; however, in a series of dehydrated children with gastroenteritis who had metabolic acidosis and increased anion gap, 88% had BUN concentration ≤18 mg/dL. The authors found bicarbonate and anion gap more sensitive indices in this setting.In chronic progressive renal disease, about three-quarters of the renal parenchyma must be damaged or destroyed before azotemia develops.
Serum (preferred) or plasma
Gel-barrier tube, green-top (lithium heparin) tube, or lavender-top (EDTA) tube; do not use ammonia heparin tube.
Type Gender Age-Group Value
Urea Nitrogen
< 18 years
7 - 20 mg/dL
Urea Nitrogen
>18 years
5 - 18mg/dL
Average price range of the test is between Rs.80 to Rs.350 depending on the factors of city, quality and availablity.
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