Editing Azotemia (section)

==Signs and symptoms==
* Oliguria or anuria (decreased or absent urine output)
* Fatigue
* [[Asterixis]] (flapping tremor)
* Decreased alertness
* Confusion
* Pale skin
* [[Tachycardia]] (rapid pulse)
* [[Xerostomia]] (dry mouth)
* Thirst
* [[Edema]], [[anasarca]] (swelling)
* Orthostatic blood pressure (fluctuates depending on body position)
* [[Uremic frost]], a condition that occurs when [[urea]] and urea derivatives are secreted through the skin in sweat, which evaporates away to leave solid uric compounds, resembling a [[frost]].

A [[urinalysis]] will typically show a decreased urine sodium level, a high urine [[creatinine]]-to-serum creatinine ratio, a high urine urea-to-serum urea ratio, and concentrated urine (determined by osmolality and specific gravity). None of these is particularly useful in diagnosis.{{citation needed|date=November 2021}}

In pre-renal and post-renal azotemias, elevation of urea exceeds that of the creatinine (i.e., BUN>12*creatinine).  This is because urea is readily reabsorbed by the kidneys while creatinine is not.  In [[congestive heart failure]] (a cause of pre-renal azotemia) or any other condition that causes poor perfusion of kidneys, the sluggish flow of glomerular filtrate results in excessive absorption of urea and elevation of its value in blood.  Creatinine, however, is not absorbable and therefore does not rise significantly.  Stasis of urine in post-renal azotemia has the same effect.{{citation needed|date=November 2021}}