A raised urea level > 7.8 mmol/L is considered uraemia, and the following are usual causes of an increased serum urea:
- Renal failure or disease (acute or chronic)
- Dehydration due to low fluid intake, excessive fluid loss (vomiting, diarrhoea)
- Excessive renal loss from diuretic use
- Decreased renal perfusion causing low circulatory states: CCF, heart failure, severe hypotension, hypovolaemic shock
- Gastrointestinal haemorrhage
- Acute-on-chronic renal failure
- High protein diet
- Advancing age
- Medications: corticosteroids, tetracyclines
- Catabolic state resulting in tissue damage: from severe infection, post-major surgery, trauma, starvation states
Causes of low urea < 2.5mmol/L
- Pregnancy low protein diet
- excess water intake,
- advanced liver disease (cirrhosis, liver failure)
