Final answer:
Uremia or increased blood urea can be classified into pre-renal, renal, or post-renal causes. Pre-renal uremia can result from dehydration affecting kidney perfusion. Renal and post-renal causes include kidney disorders and urinary tract obstructions, respectively.
Step-by-step explanation:
Causes of Uremia
- Uremia, or an increased blood urea level, can be classified as pre-renal, renal, or post-renal in origin.
Pre-Renal Uremia
- Pre-renal causes of uremia include situations leading to decreased kidney perfusion such as dehydration from vomiting or diarrhea. This dehydration can result from pyloric obstruction, chronic intestinal obstruction, or ulcerative colitis, which all cause hemoconcentration and reduced glomerular filtration rate (GFR), leading to elevated blood urea levels.
Renal Uremia
- Renal causes of uremia may arise from kidney disorders such as advanced glomerulonephritis, which can cause acidosis and increased levels of blood indica (indoxyl potassium sulphate). Severe crises, such as autoimmune disorders, can also lead to acute renal failure.
Post-Renal Uremia
- Post-renal causes of uremia, such as urinary tract obstructions from urolithiasis (kidney stones), can also elevate blood urea levels.
Moreover, conditions like increased blood pressure due to fluid overload, production of vasoactive hormones, and marked sulphate retention can contribute to the development of uremia. Symptoms of uremia range from lethargy to more severe complications such as pericarditis and encephalopathy. In stages of advanced uremia, urea may be excreted through sweating, sometimes leading to "uremic frost" on the skin.