urea-Chemical Pathology

Urea synthesis,Significant

1. Urea Source : Principal end product of Protein and amino acid metabolism. major end product of nitrogen metabolism in humans and mammals . Water soluble and excreted in Urine. Urea Constitutes approx one half of total urinary solutes(25g/dl).

2. UREA NH3 the product of oxidative deamination reaction , is toxic even small amount and must be removed from the body . Urea cycle is the conversion reaction of NH3 to urea. This reaction occurs in the liver ( certain occur in cytosol and mitochondria . The urea is transported to the kidney where it is excreted

3. UREA Introduction : Urea is major end product of nitrogen metabolism in humans and mammals . NH3 the product of oxidative deamination reaction , is toxic even small amount and must be removed from the body . Urea cycle is the conversion reaction of NH3 to urea. This reaction occurs in the liver( certain occur in cytosol and mitochondria . The urea is transported to the kidney where it is excreted

4. SYNTHESIS OF UREA Urea cycle also known as kreb’s urea cycle or ornithine cycle . Site : Liver Sub cellular organelle : two steps occur in the mitochondria , remaining in the cytoplasm . Converts NH3 into harmless Urea

5. Over view of Urea cycle Basic Concept: Urea cycle is a chemical reaction in our body that converts a waste ammonia(Toxic substance) in less Toxic form (Urea) then urea is concentrated and converted in to urine . Ammonia (NH3) Its highly toxic and cannot store in body .

6. Or dinary Ca r less C rappers A re A lso Fu rious A bout Ur ination. Ornithine Carbon Phosphate Citrulin Aspartate Argininosuccinate Fumarate Arginine Urea.

7. CLINICAL SIGNIFICANCE: An increased level of urea in blood is called Azotemia Azotemia may be divided into three main categories: Prerenal Renal Postrenal 1: PRE RENAL: Prerenal azotemia is the result of inadequate perfusion of the kidneys and diminished glomerular filtration. Factors that can cause decreased renal blood flow include Congestive heart failure, Shock, Dehydration, Hemorrhage and diminished blood volum e.

8. : Additional causes of increased plasma urea include High protein diet Muscle wasting as in starvation Treatment with glucocorticoids Increased protein breakdown which can occur for example; with fever, Stress and burns.

9. UREMIA: Uremia is a clinical syndrome comprised of a marked elevation in plasma Urea accompanied by academia and electrolyte imbalance (especially potassium Elevation) of renal failure. It is eventually fatal if not treated by dialysis. Patient with uremia present not only with academia and water and electrolyte Imbalance but also with nausea, vomiting, anemia.

10. POST RENAL AZOTEMIA: Post renal azotemia is usually the result of urinary tract obstruction and a consequent increase in the back-diffusion of urea from the renal tubules into The circulation. CAUSES: Nephrolithiasis Hypertrophy of the prostate gland Tumor of the gastro urinary tract .

11. CAUSES OF DECREASE IN PLASMA UREA CONCENTRATION Poor nutrition High fluid intake Excessive administration of intravenous fluids Pregnancy Severe liver disease

12. BUN REFERENCE INTERVAL: Urea in blood is usually reported as BUN and expressed in mg/ dL . BUN mass unit can be converted to urea mass units by multiplying by 2.14(60/28 = 2.14, Where 60 is the molecular weight of urea, and 28 is the weight of the two nitrogen atoms). The reference interval for serum or plasma urea nitrogen of healthy adults is 8 to 20 mg/ dL .

13. Overview As Already discussed A common blood test, the blood urea nitrogen (BUN) test reveals important information about how well your kidneys and liver are working. A BUN test measures the amount of urea nitrogen that's in your blood. Here's how your body typically forms and gets rid of urea nitrogen:

14. Once Again….. Your liver produces ammonia — which contains nitrogen — after it breaks down proteins used by your body's cells. The nitrogen combines with other elements, such as carbon, hydrogen and oxygen, to form urea, which is a chemical waste product. The urea travels from your liver to your kidneys through your bloodstream.

15. Healthy kidneys filter urea and remove other waste products from your blood. The filtered waste products leave your body through urine. A  BUN test can reveal whether your urea nitrogen levels are higher than normal, suggesting that your kidneys or liver may not be working properly.

16. Why it's done You may need a blood urea nitrogen test: If your doctor suspects that you have kidney damage If your kidney function needs to be evaluated To help determine the effectiveness of dialysis treatment if you're receiving hemodialysis or peritoneal dialysis As part of a blood test group to help diagnose a number of other conditions, such as liver damage, urinary tract obstruction, congestive heart failure or gastrointestinal bleeding — although an abnormal BUN test result alone doesn't confirm any of these conditions

17. Cont … If kidney problems are the main concern, the creatinine levels in your blood will likely also be measured when your blood is tested for urea nitrogen levels. Creatinine is another waste product that healthy kidneys filter out of your body through urine. High levels of creatinine in your blood may be a sign of kidney damage. Your doctor may also test how well your kidneys are removing waste from the blood. To do this, you may have a blood sample taken to calculate your estimated glomerular filtration rate (GFR). The GFR estimates the percentage of kidney function you have left

18. Results Results of the blood urea nitrogen test are measured in milligrams per deciliter (mg/ dL ) in the United States and in millimoles per liter ( mmol /L) internationally. In general, around 7 to 20 mg/ dL (2.5 to 7.1 mmol /L) is considered normal. But normal ranges may vary, depending on the reference range used by the lab, and your age. Ask your doctor to explain your results. Urea nitrogen levels tend to increase with age. Infants have lower levels than other people do, and the range in children varies .

19. High blood urea nitrogen level Generally , a high blood urea nitrogen level means your kidneys aren't working well. But elevated blood urea nitrogen can also be due to:

20. Cont …. Urinary tract obstruction Congestive heart failure or recent heart attack Gastrointestinal bleeding Dehydration, resulting from not drinking enough fluids or for other reasons Shock Severe burns Certain medications, such as some antibiotics A high-protein diet If kidney damage is a concern, ask your doctor what factors may be contributing to the damage and what steps you can take to try to control them.