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, 09:34 18 mar 2012
Also known as '''''Blood Urea Nitrogen — BUN
==Description==
Urea is a form of nitrogenous waste formed from [[Ammonia|ammonia]] via the urea cycle in the liver. It freely crosses lipid membranes and is filtered into the glomerular filtrate in the renal glomerulus. A proportion of this filtered urea is reabsorbed passively before final excretion and it forms a vital of the concentration gradient needed to prevent passive diuresis.
==Clinical Significance==
An increase in serum concentrations of urea and creatinine is known as '''[[Azotaemia|azotaemia]]''' and it is found almost exclusively in animals with kidney disease.
Blood urea coentration may be elevated independently of creatinine for the following reasons:
*Gastro-intestinal haemorrhage, as with [[Gastric Ulceration - Dog|gastro-duodenal ulceration]].
*Diet with high protein or purine content, such as liver.
*Increased catabolism of body tissues, particularly muscle, which may occur in pyrexic animals or those with systemic disease.
Reduced urea concentration may occur due to:
*Over-enthusiastic fluid therapy, diluting the urea present in the blood.
*Disease that cause polyuria and/or polydipsia may cause 'medullary washout' of urea. Common examples include pyschogenic polydipsia, [[Diabetes Insipidus|diabetes insipidus]] and [[Hyperadrenocorticism|Cushing's disease]].
*Reduced synthesis with [[Portosystemic Shunt|porto-systemic shunts]], [[Hepatic Microvascular Dysplasia|microvascular dysplasia]] or liver failure.
*A diet with a low protein content or malnutrition.
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[[Categoría:Cambios Bioquímica de la Sangre]][[Category:To_Do_-_Blood]]
[[Categoría:Cristina Castillo]]