Difference between revisions of "Azotaemia"
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Azotaemia may cause the clinical syndrome of [[Uraemia|'''uraemia''']], affecting multiple organ systems. The causes of azotaemia are usually divided into pre-renal, renal and post-renal: | Azotaemia may cause the clinical syndrome of [[Uraemia|'''uraemia''']], affecting multiple organ systems. The causes of azotaemia are usually divided into pre-renal, renal and post-renal: | ||
===Pre-renal azotaemia=== | ===Pre-renal azotaemia=== | ||
| − | This occurs when the kidney receives insufficient oxygen to maintain its | + | This occurs when the kidney receives insufficient oxygen via blood flow to maintain its normal metabolic processes: |
*'''Dehydration/hypovolaemia''', reducing renal blood flow. | *'''Dehydration/hypovolaemia''', reducing renal blood flow. | ||
*'''Heart failure''' results in a reduced cardiac output, reducing renal blood flow. | *'''Heart failure''' results in a reduced cardiac output, reducing renal blood flow. | ||
*'''Anaemia''' reduces the amount of oxygen delivered to the kidneys. | *'''Anaemia''' reduces the amount of oxygen delivered to the kidneys. | ||
*'''Portal hypertension''' may result in splanchnic pooling of blood and reduced renal blood flow. | *'''Portal hypertension''' may result in splanchnic pooling of blood and reduced renal blood flow. | ||
| + | |||
===Renal azotaemia=== | ===Renal azotaemia=== | ||
This occurs following a direct insult to the kidney: | This occurs following a direct insult to the kidney: | ||
Revision as of 11:04, 3 November 2010
Introduction
Azotaemia refers to an increase in the blood concentrations of urea and creatinine. Azotaemia occurs almost exclusively with renal failure that results in an inability to excrete these two metabolic products. Urea and Creatinine vary in the extent of the increase induced by renal pathologies (creatinine can show substantial increases from baseline, whereas smaller increases in urea are significant as levels generally increase by a much smaller factor) and also the timing of the increase - creatinine levels will rise and fall more quickly than changes in urea and can therefore be more useful in monitoring response to treatment.
Clinical Significance
Azotaemia may cause the clinical syndrome of uraemia, affecting multiple organ systems. The causes of azotaemia are usually divided into pre-renal, renal and post-renal:
Pre-renal azotaemia
This occurs when the kidney receives insufficient oxygen via blood flow to maintain its normal metabolic processes:
- Dehydration/hypovolaemia, reducing renal blood flow.
- Heart failure results in a reduced cardiac output, reducing renal blood flow.
- Anaemia reduces the amount of oxygen delivered to the kidneys.
- Portal hypertension may result in splanchnic pooling of blood and reduced renal blood flow.
Renal azotaemia
This occurs following a direct insult to the kidney:
- Exogenous toxins including heavy metals, aminoglycosides, tetracyclines, polymixin B, cisplatin, lilies in cats and grapes in dogs.
- Endogenous toxins including haemoglobin, myoglobin and calcium.
- Infection as in pyelonephritis, interstitial nephritis (as caused by Leptospira spp. or granulomatous nephritis (as caused by the dry form of Feline Infectious Peritonitis).
- Glomerulonephritis and amyloidosis.
- Neoplasia, including adenocarcinoma in dogs and lymphoma in cats.
Post-renal azotaemia
This occurs following obstructions within the urinary tract:
- Urolithiasis
- Rupture of the urinary tract, often due to trauma and causing uroabdomen.
- Neoplasia, including transitional cell carcinoma of the bladder and prostatic neoplasia.