Mr. T is 77-year-old man with acute kidney injury (AKI).
What is the differential diagnosis of AKI? How would you frame the differential?
CONSTRUCTING A DIFFERENTIAL DIAGNOSIS
AKI is a syndrome defined as a reduction in kidney function that has occurred within the last 7 days. AKI can occur in patients with no known kidney disease but is more likely to develop in patients with preexisting kidney disease. Table 28-1 summarizes the current diagnostic criteria and staging for AKI, and acute and chronic kidney disease (CKD).
Table 28-1.Diagnostic criteria and staging for kidney disease. |Favorite Table|Download (.pdf) Table 28-1. Diagnostic criteria and staging for kidney disease.
| || || ||Staging |
|Syndrome ||Serum Creatinine (Scr)/GFR Criteria ||Evidence of Kidney Damage1 ||Stage2 ||Scr ||Urinary Output |
|Acute kidney injury (AKI) || |
• Increase in serum creatinine by ≥ 0.3 mg/dL within 48 hours or
• Increase to ≥ 1.5 times baseline within 7 days or
• Urine volume < 0.5 mL/kg/h for 6 hours
|Not required for diagnosis || |
↑ by ≥ 0.3 or 1.5–1.9 times baseline
2–2.9 times baseline
3 times baseline or ≥ 4 mg/dL or dialysis
< 0.5 mL/kg/h for 6–12 hours
< 0.5 mL/kg/h for ≥ 12 hours
< 0.3 mL/kg/h for ≥ 24 hours or anuria
|Acute kidney disease (AKD)3 || |
• AKI or
• GFR < 60 mL/min for < 3 months or
• Decrease in GFR by ≥ 35% or increase in serum creatinine > 1.5 times baseline for < 3 months
|Present for < 3 months ||No staging || || |
|Chronic kidney disease (CKD)3 ||GFR < 60 mL/min for > 3 months ||Present for > 3 months || ||GFR stages ||Albuminuria stages (ACR) |
| || || || || |
G1 > 90
G5 < 15
A1 < 30 mcg/mg
A2 30–299 mcg/mg
A3 ≥ 300 mcg/mg
The framework for the differential diagnosis of AKI is a combination of anatomic and pathophysiologic:
Prerenal (due to renal hypoperfusion)
Gastrointestinal fluid loss
Decreased effective circulating volume (with or without hypotension)
Heart failure (HF)
Anesthesia- and medication-induced
Relative hypotension below patient’s autoregulatory level
Changes in renal hemodynamics
Nonsteroidal antiinflammatory drugs (NSAIDs) (including cyclooxygenase (COX)-2 inhibitors)
Angiotensin-converting enzyme inhibitors/angiotensin receptor blockers
Renal artery thrombosis or embolism...