Prerenal azotemia

Alternative names:

azotemia, prerenal; renal underperfusion; uremia

Symptoms:

• decreased or no urine produced
• fatigue
• decreased alertness
• confusion
• pale skin color
• rapid pulse
• dry mouth
• thirst
• swelling (edema, anasarca)

Additional symptoms that may be associated with this disease:

• urination, excessive at night
• abdominal pain

Signs and tests:

An examination may show signs of low cardiac output or signs of hypovolemia. The blood pressure may be low or may drop when the person stands up. The pulse pressure (difference between systolic blood pressure and diastolic blood pressure) may be reduced. The heart rate may be rapid. Skin turgor may be poor, with dry mucous membranes. The neck veins may be collapsed. There may be little or no urine in the bladder even when drained by a catheter. If the condition is prolonged, other signs of acute renal failure may be present.

A urinalysis may show decreased kidney function preserving the ability of the tubules. Nitrogen wastes and electrolytes continue to be excreted, but at abnormally low rates.

• Urine sodium may be low, with fractional excretion at less than 1%.
• Urine creatinine to serum creatinine ratio is high.
• Urine urea to serum urea (BUN) ratio is high.
• Fractional excretion of urea is low.
• Osmolality and specific gravity show concentrated urine.

Blood lab tests show a rapid accumulation of nitrogen wastes:

• increased BUN
• increased creatine
• increased BUN/creatinine ratio