Pre-Renal Azotemia is characterized by all of the following, EXCEPT:
Azotemia refers to increase in BUN and creatinine. Azotemia can be prerenal, renal or postrenal. Pre renal azotemia occurs when there is a reduction in the effective aerial blood flow to the kidney, either from a reduction in extracellular volume or in conditions where effective circulating volume is reduced despite normal total extracellular volume. LAB findings include: FeNa is less than 1 %,- proximal tubular function is normal, so it reabsorbs sodium and water, so less sodium is available at the distal tubule leading to greater secretion of renin. This inturn increase aldosterone secretion and increased distal sodium reabsorption resulting in low Fractional excretion of sodium. BUN and creatinine levels are elevated. BUN/creatinine ratio >20:1 as filtered urea is reabsorbed and creatinine is excreted. Urine osmolality is greater than 500mosml/kg. Urine sodium is less than 20meq/l consistent witjavascript:void ('14')h normal tubular function. Ref: CURRENT Diagnosis & Treatmentchapter, Chapter 9; Advances in clinical chemistry, Volume 29 By Herbe E. Spiegel, Page 137; Nephrology in 30 Days By Robe F. Reilly, Mark A. Perazella, Page 234.
Fractional Excretion of Na < 1%
Urinary osmolality > 500 mosm/kg
Urinary sodium concentration > 40 meq/1
Reversible with replacement fluids