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Uremia
Synonym(s): Uremic syndrome
Introduction
- Polysystemic toxic syndrome resulting from severe azotemia Azotemia due to decreased renal function. Azotemia is an increased concentration of non-protein nitrogenous compounds, eg urea and creatinine, in the blood.
- Cause: acute or chronic renal failure or prolonged urinary tract obstruction.
- Signs: vomiting, anorexia, lethargy/depression, anemia, weakness, hypothermia, oral ulcers, melena, muscle, tremors, seizures.
- Diagnosis: signs, blood biochemistry, urinalysis.
- Prognosis: depends on severity of renal damage.
Presenting signs
- Acute or chronic renal failure Kidney: chronic kidney disease (CKD) with azotemia, metabolic acidosis, oliguria or polyuria, mineral and electrolyte abnormalities.
- Gastrointestinal complications.
- Chronic renal failure Urinary incontinence.
- Non-regenerative anemia (if the renal failure is chronic).
- Systemic hypertension Hypertension.
- Soft tissue calcification may be visible on radiographs.
- Oral ulceration, halitosis.
- Hemorrhagic diathesis.
- Urinary tract obstruction Urinary obstruction with azotemia, metabolic acidosis and hyperkalemia.
- Renal osteodystrophy (demineralization) Renal secondary hyperparathyroidism.
- Hypokalemia → muscle weakness.
- Depression, tremors, seizures.
- Scleral and conjunctival injection.
- Hypothermia +/- bradycardia.
- Uremic pericarditis and secondary cardiac disease.
- Respiratory compromise: tachypnea due to anemia, metabolic acidosis or uremic pneumonitis.
Acute presentation
- Acute renal failure Kidney: acute kidney injury (AKI) with oliguria, dehydration, circulatory collapse, hyperkalemia and metabolic acidosis.
Geographic incidence
- Infectious causes of renal failure may occur more frequently in some geographical areas, eg Leptospirosis, Lyme nephropathy.
Age predisposition
- Chronic renal failure is most common in geriatric dogs.
Breed/Species predisposition
- Many breeds are prone to juvenile renal disease which results in chronic renal failure Kidney: chronic kidney disease (CKD).
- A few breeds are prone to renal amyloidosis Amyloidosis.
- Golden Retrievers Retriever: Golden and Labrador Retrievers Retriever: Labrador have an increased incidence of Lyme nephropathy.
Cost considerations
- Hemodialysis or peritoneal dialysis.
- Intravenous fluid therapy, anti-ulcer medications, nutritional support, etc.
- Dietary modification.
Special risks
- Increased risk of anesthesia Anesthesia: in renal insufficiency - pay particular attention to fluid balance.
- Increased risk from dehydration - warn owners to avoid heat stress and provide free access to water at all times.
Warn owner of increased risk of anesthesia
Pathogenesis
Etiology
Acute renal failure
- Tubular failure due to dehydration, circulatory failure, hypovolemia (prerenal uremia).
- Toxins: aminoglycosides Therapeutics: antimicrobial drug , ethylene glycol Ethylene glycol poisoning , paraquat Paraquat poisoning , heavy metals, eg cisplatin.
- Vascular obstruction, ischemia.
- Hypercalcemia Blood biochemistry: total calcium.
- Acute interstitial nephritis Chronic interstitial nephritis.
- Glomerular failure due to infection, auto-immune disease or toxemia (pyometra/sepsis).
- Urinary tract obstruction Urinary obstruction (post-renal uremia).
- Trauma.
- Acute diffuse pyelonephritis Kidney: pyelonephritis.
- Decompensating chronic renal disease Kidney: chronic kidney disease (CKD).
- Congenital renal dysplasia Kidney: dysplasia or other juvenile renal diseases.
- Chronic interstitial nephritis Chronic interstitial nephritis.
- Glomerulonephritis Glomerulonephritis.
- Neoplasia Kidney: neoplasia.
- Pyelonephritis Kidney: pyelonephritis.
- Amyloidosis Amyloidosis.
- Hydronephrosis Hydronephrosis / hydroureter.
Predisposing factors
General- Post-renal failure - urinary tract obstruction Urinary obstruction.
Specific
- Acute renal failure Kidney: acute kidney injury (AKI).
- Chronic renal failure Kidney: chronic kidney disease (CKD).
Pathophysiology
Acute renal failure
- Prerenal, renal or post-renal azotemia → decreased glomerular filtration → oliguria → retention of waste products → toxemia/uremia.
- Loss of functional nephrons → inability to concentrate urine → polyuria, polydipsia.
- Retention of waste products → toxemia → catabolism of body tisues → anorexia.
- Toxemia → increased erythrocyte fragility, bone marrow depression → anemia.
- Toxemia → oral and gastrointestinal ulceration → vomiting, diarrhea and anorexia.
- Loss of functional nephrons → decreased GFR → increased phosphorus → decreased calcium → increased PTH → normalizes calcium and phosphorus but causes renal secondary osteodystrophy.
Timecourse
- Acute or chronic.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Brassard J A , Meyers K M, Person M et al (1994) Experimentally induced renal failure in the dog as an animal model of uremic bleeding. J Lab Clin Med 124 (1), 48-54 PubMed.
Other sources of information
- Schluman R L & Krawiec D R (2000)Gastrointestinal Complications of Uremia.In: Kirk'sCurrent Veterinary Therapy XIII. J D Bonagura (ed). W B Saunders. pp 864-866.