What is included in supportive therapies for prerenal azotemia?

Updated: Sep 19, 2018
  • Author: Moro O Salifu, MD, MPH, FACP; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

Diarrhea often causes isotonic volume loss that necessitates replacement with normal saline. Normal–anion gap metabolic acidosis occurring with diarrhea warrants infusion of bicarbonate in 0.5% normal saline.

Diuretic-induced volume depletion, especially in the elderly, manifests as dehydration, hyponatremia, [12] and, occasionally, hypokalemia. The treatment of choice consists of normal saline infusion and correction of hypokalemia.

Decreased cardiac output requires optimization of cardiac performance through careful use of diuretics, an angiotensin-converting enzyme (ACE) inhibitor, beta blockers, nitrates, positive inotropic agents (including dobutamine), and, when indicated, specific therapy for the cause of impaired cardiac function.

When ACE inhibitors are contraindicated because of hyperkalemia, the combination of nitrates and hydralazine offers an alternative. Because these patients tend to have risk factors for macrovascular disease, the diagnosis of ischemic nephropathy or atheroembolic disease should be entertained when renal function continues to worsen despite optimization of cardiac function.

Reduced effective arterial volume due to systemic shunting can result from sepsis or liver failure. Severe edema, hyponatremia, and hypoalbuminemia often pose management problems. Decreased oncotic pressure, increased vascular permeability, and exaggerated salt and water retention shift the Starling forces toward formation of interstitial fluid. Effective treatment of sepsis with antibiotics and of hypotension with dopamine and norepinephrine is mandated. Crystalloid replacement can be tried, but it often leads to more edema.

In severely hypoalbuminemic patients, salt-poor albumin infusion may be undertaken, but there is no conclusive evidence of benefit.

Adequate nutrition and effective treatment of sepsis may improve oncotic pressure and normalize vascular permeability, thereby decreasing the systemic shunting. The net result is improved renal perfusion, decreased salt and water retention, improved output, and edema. In hepatorenal syndrome (HRS), the average survival is 1-2 weeks; however, there is evidence that the kidneys will recover with early liver transplantation. Occasionally, renal function is advanced, necessitating replacement therapy.


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