Phases of Acute Renal Failure
- Initiation period: begins with the initial insult and ends when oliguria develops.
- Oliguria period: UOP < 400 ml/day, increase in urea, creatinine, uric acid, K &
magnesium. Some people have normal urine output (2 L/d)
Diuretic – UOP ^ to as much as 4000 mL/d but BUN & Cretinine still high, at end of
this stage may begin to see improvement
Recovery – things go back to normal. It may take up to 3-12 months
The oliguria period is accompanied by an increase in the serum concentration of
substances usually excreted by the kidneys (urea, creatinine, uric acid, organic acids,
and the intracellular cations [potassium and magnesium]). The minimum amount of
urine needed to rid the body of normal metabolic waste products is 400 mL. In this
phase uremic symptoms first appear and life-threatening conditions such as
hyperkalemia develop.
Some patients have decreased renal function with increasing nitrogen retention, yet
actually excrete normal amounts of urine (2 L/day or more). This is the nonoliguric
form of renal failure and occurs predominantly after exposure of the patient to
nephrotoxic agents; it may also occur with burns, traumatic injury, and the use of
halogenated anesthetic agents.
The diuresis period is marked by a gradual increase in urine output, which signals that
glomerular filtration has started to recover. Laboratory values stop increasing and
eventually decrease. Although the volume of urinary output may reach normal or
elevated levels, renal function may still be markedly abnormal. Because uremic
symptoms may still be present, the need for expert medical and nursing management
continues. The patient must be observed closely for dehydration during this phase; if
dehydration occurs, the uremic symptoms are likely to increase.
The recovery period signals the improvement of renal function and may take 3 to 12
months. Laboratory values return to the patient's normal level. Although a permanent
1% to 3% reduction in the GFR is common, it is not clinically significant.
Acute Renal Failure S & S
- The patient may appear critically ill and lethargic.
- The skin and mucous membranes are dry from dehydration.
- Central nervous system signs and symptoms include drowsiness, headache, muscle
twitching, and seizures.
- Urine output varies (scanty to normal volume),? hematuria & urine has a low specific
gravity