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| | ==Description== | | ==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. | | 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. |
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| − | Urea is principally a product of amino acid deamination in the liver. Urea is primarily excreted by the kidneys and is the most commonly used test of renal function with creatinine. References: [[NationWide Laboratories]]
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| | ==Clinical Significance== | | ==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. | | 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. |
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| | *A diet with a low protein content or malnutrition. | | *A diet with a low protein content or malnutrition. |
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| − | == Small Animals ==
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| − | === Increased urea, renal azotaemia ===
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| − | * Acute renal failure
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| − | * Chronic renal failure
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| − | === Increased urea, prerenal azotaemia ===
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| − | * Dehydration
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| − | * Shock
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| − | * High protein diet
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| − | * Fever
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| − | * Reduced cardiac output
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| − | * Hyperthyroidism
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| − | * Hypoadrenocorticism
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| − | * Gastrointestinal haemorrhage
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| − | === Increased urea, postrenal azotaemia ===
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| − | * Feline urological syndrome
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| − | * Bladder rupture
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| − | * Calculi
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| − | * Neoplasia
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| − | * Perineal herniation
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| − | === Causes of a low urea concentration ===
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| − | * Polydipsia/polyuria (due to causes other than renal disease)
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| − | * Hepatic insufficiency, especially portosystemic shunt
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| − | * Low protein diet
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| − | * Late pregnancy
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| − | * Anabolic steroids
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| − | === Complementary tests ===
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| − | Creatinine and phosphorus. Urine specific gravity, urinalysis, glomerular filtration rate and SDMA.
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| − | == Equine ==
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| − | === Increased urea, prerenal azotaemia ===
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| − | * Dehydration
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| − | * Reduced renal perfusion
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| − | * Congestive heart failure
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| − | * Excessive muscle catabolism
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| − | * High protein diet
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| − | * Grass sickness
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| − | === Increased urea, renal azotaemia ===
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| − | * Acute renal failure
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| − | * Chronic renal failure
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| − | === Increased urea, postrenal azotaemia ===
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| − | * Obstruction, ruptured bladder
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| − | * Ruptured bladder in neonatal foals
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| − | * Low urea concentrations
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| − | * Hepatic insufficiency
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| − | * Young foals (normal by 60 days)
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| − | === Complementary tests ===
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| − | Creatinine and phosphorus. Urine specific gravity (<1.020 in a dehydrated or azotaemic horse suggests renal tubular dysfunction). Urine clearance or fractional electrolyte excretion ratios (renal
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| − | tubular dysfunction).
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| − | Test Codes - Please visit www.nwlabs.co.uk or see our current price list for more information
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| − | == References ==
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| − | Text referenced 'Nationwide Laboratories' [[NationWide Laboratories]]
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| − | Small Animals: [[NationWide Laboratories]]
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| − | Equine: [[NationWide Laboratories]]
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