| Table 3: |
|
How
to Evaluate Patients with ARF
|
| 1.
Review records, obtain history, and perform physical examination |
Findings
that suggest prerenal causes
|
Volume depletion
Congestive heart failure
Severe liver disease or other edematous states
|
Findings
that suggest postrenal causes
|
Palpable bladder
or hydronephrotic kidneys
Enlarged prostate
Abnormal pelvic examination
Large residual bladder urine volume
History of renal calculi (perform ultrasound to screen for urinary tract
obstruction)
|
Findings
that suggest intrinsic renal disease
|
Exposure to nephrotoxic
drugs, hypotension
Recent radiographic procedures with contrast
|
|
2.
Examine the urine sediment
|
No abnormalities:
suspect prerenal or postrenal azotemia
Eosinophils: suspect acute interstitial nephritis
Red blood cell casts: suspect glomerulonephritis or vasculitis
Renal tubular epithelial cells and muddy brown casts: suspect acute
tubular necrosis
|
| 3.
Calculate urinary indices |
Findings
that suggest prerenal azotemia or glomerulonephritis
|
Urinary sodium concentration
<20 mEq/L
Urine:plasma creatinine ratio >30
Renal failure index <1
(Renal failure index = urinary sodium concentration X plasma creatinine
concentration/ urinary creatinine concentration)
Urine osmolality >500
|
| 4.
Findings that suggest acute tubular necrosis or postrenal azotemia |
Urinary sodium concentration
>40 mEq/L
Urine:plasma creatinine ratio <20
Renal failure index >1
Urine osmolality <400
|
| Adapted
from Nally JV Jr. Acute renal failure. In: Stoller JK, Ahmad M, Longworth
DL, eds. The Cleveland Clinic Intensive Review of Internal Medicine.
Philadelphia: Lippincott, Williams & Wilkins;2000:565-572. |