Medication Summary
The goals of therapy are to increase renal perfusion and to maintain urine output. Drugs used in the management of patients with azotemia include diuretics, adrenergic agents, plasma volume expanders, and corticosteroids. Specific therapies for various systemic conditions affecting the kidney are discussed in other articles.
Diuretics, Other
Class Summary
Diuretics are used to induce urine output in acute tubular necrosis (ATN) and to treat edema and hypertension. They increase urine excretion by inhibiting sodium and chloride reabsorption at different sites in the nephron.
Furosemide (Lasix)
Furosemide is the drug of choice as a diuretic. It inhibits sodium chloride reabsorption in the thick ascending limb of the loop of Henle.
Hydrochlorothiazide (Microzide)
Hydrochlorothiazide (HCTZ) acts on the distal nephron to impair sodium reabsorption, enhancing sodium excretion. It has been in use for more than 40 years and is generally an important agent for the treatment of essential hypertension.
Chlorothiazide (Diuril)
Chlorothiazide inhibits the reabsorption of sodium in distal tubules, causing increased excretion of sodium and water, as well as of potassium and hydrogen ions.
Metolazone (Zaroxolyn)
Metolazone is given as an adjunct to furosemide in severe edematous states or when furosemide alone does not achieve adequate diuresis. It increases excretion of sodium, water, potassium, and hydrogen ions by inhibiting reabsorption of sodium in distal tubules. Metolazone may be more effective in the setting of impaired renal function.
Volume Expanders
Class Summary
Plasma volume expanders increase plasma oncotic pressure and mobilize fluid from the interstitial space into the intravascular space in hypoalbuminemic patients. They enhance delivery of furosemide to distal tubule.
Albumin (Albuminar, Plasbumin, Albutein)
Albumin is supplied as a 5% solution in 250 mL or a 25% solution in 50 mL. The choice between the 2 formulations is based on whether patient requires additional fluid replacement. Albumin is not used for nutritional supplementation; thus, attempts should be made to improve patient's nutrition.
Corticosteroids
Class Summary
Corticosteroids are potent anti-inflammatory agents and immunosuppressants. They suppress humoral and cellular response to tissue injury, thereby reducing inflammation.
Prednisone
Prednisone is commonly used for many forms of glomerulonephritis and interstitial nephritis. Once the diagnosis is confirmed, a trial of oral prednisone (starting at 1 mg/kg/day and tapering over 6 weeks) may be considered.
Prednisolone (Orapred, Pediapred, Millipred)
Corticosteroids act as potent inhibitors of inflammation. They may cause profound and varied metabolic effects, particularly in relation to salt, water, and glucose tolerance, in addition to their modification of the immune response of the body. Once the diagnosis is confirmed, a trial of oral prednisolone (starting at 1 mg/kg/day and tapering over 6 weeks) may be considered.
Methylprednisolone (Medrol, Solu-Medrol, Depo-Medrol)
Methylprednisolone decreases inflammation by suppressing the migration of PMNs and reversing increased capillary permeability. In severe cases, a trial of intravenous pulse methylprednisolone (1 g for 3 days) may be considered once the diagnosis is confirmed.
Alpha/Beta Adrenergic Agonists
Class Summary
Adrenergic agents stimulate vasodilation of the renal vasculature and enhance perfusion.
Dopamine
Above a critical dose (renal dose), dopamine becomes a potent vasoconstrictor. Renal-dose dopamine is used widely, but a clear benefit has not been established.
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Graph shows relation of glomerular filtration rate (GFR) to steady-state serum creatinine and blood urea nitrogen (BUN) levels. In early renal disease, substantial decline in GFR may lead to only slight elevation in serum creatinine. Elevation in serum creatinine is apparent only when GFR falls to about 70 mL/min.
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Diagnostic indices in azotemia. Although such indices are helpful, it is not necessary to perform all these tests on every patient. Comparison should always be made with patients' baseline values to identify trends consistent with increase or decrease in effective circulating volume. Use of some of these indices may be limited in certain clinical conditions, such as anemia (hematocrit), hypocalcemia (serum calcium), decreased muscle mass (serum creatinine), liver disease (blood urea nitrogen [BUN], total protein, and albumin), poor nutritional state (BUN, total protein, and albumin), and use of diuretics (urine sodium). Fractional excretion of urea and fractional excretion of trace lithium appear to be superior for assessing prerenal status in patients on diuretics.
