Prerenal azotemia

  • Definition
    • Prerenal azotemia is an abnormally high level of nitrogen waste products in the blood.

  • Alternative Names
    • Azotemia - prerenal; Uremia; Renal underperfusion

  • Causes
    • Prerenal azotemia is common, especially in people who are in the hospital.

      The kidneys filter the blood. They also make urine to remove waste products. When the amount, or pressure, of blood flow through the kidney drops, filtering of the blood also drops. Or it may not occur at all. Waste products stay in the blood. Little or no urine is made, even though the kidney itself is working.

      When nitrogen waste products, such as creatinine and urea, build up in the body, the condition is called azotemia. These waste products act as poisons when they build up. They damage tissues and reduce the ability of the organs to function.

      Prerenal azotemia is the most common form of kidney failure in hospitalized people. Any condition that reduces blood flow to the kidney may cause it, including:

      • Burns
      • Conditions that allow fluid to escape from the bloodstream
      • Long-term vomiting, diarrhea, or bleeding
      • Heat exposure
      • Decreased fluid intake (dehydration)
      • Loss of blood volume

      Conditions in which the heart cannot pump enough blood or pumps blood at a low volume also increase the risk for prerenal azotemia. These conditions include:

      It also can be caused by conditions that interrupt blood flow to the kidney, such as:

      • Certain types of surgery
      • Injury to the kidney
      • Blockage of the artery that supplies blood to the kidney (renal artery occlusion)
  • Symptoms
    • Prerenal azotemia may have no symptoms. Or, symptoms of the causes of prerenal azotemia may be present.

      Symptoms of dehydration may be present and include any of the following:

  • Exams and Tests
  • Treatment
    • The main goal of treatment is to quickly correct the cause before the kidney becomes damaged. People often need to stay in the hospital.

      Intravenous (IV) fluids, including blood or blood products, may be used to increase blood volume. After blood volume has been restored, medicines may be used to:

      • Increase blood pressure
      • Improve the pumping of the heart

      If the person has symptoms of acute kidney failure, treatment will likely include:

  • Outlook (Prognosis)
    • Prerenal azotemia can be reversed if the cause can be found and corrected within 24 hours. If the cause is not fixed quickly, damage may occur to the kidney (acute tubular necrosis).

  • Possible Complications
    • Complications may include:

      • Acute kidney failure
      • Acute tubular necrosis (tissue death)
  • When to Contact a Medical Professional
    • Go to the emergency room or call the local emergency number (such as 911) if you have symptoms of prerenal azotemia.

  • Prevention
    • Quickly treating any condition that reduces the volume or force of blood flow through the kidneys may help prevent prerenal azotemia.

  • References
    • Goldfarb DA, Poggio ED. Etiology, pathogenesis, and management of renal failure. In: Wein AJ, Kavoussi LR, Novick AC, et al., eds. Campbell-Walsh Urology. 10th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 43.

      Meyer TW, Hostetter TH. The pathophysiology of uremia. In: Taal MW, Chertow GM, Marsden PA, et al., eds. Brenner and Rector's The Kidney. 9th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 53.