In a patient with a baseline serum creatinine of 1.5 mg/dL, does an increase to 1.9 mg/dL meet the criteria for acute kidney injury (AKI)?

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Acute Kidney Injury (AKI) Creatinine Criteria (KDIGO)

An increase in serum creatinine from 1.5 mg/dL to 1.9 mg/dL is an absolute rise of 0.4 mg/dL. [1] This increase meets KDIGO AKI diagnostic criteria if it occurred within 48 hours. [1]

Serum Creatinine Change Calculation

Absolute serum creatinine increase: 1.9 − 1.5 = 0.4 mg/dL. [1]
Relative serum creatinine increase: 1.9 / 1.5 = 1.27 times baseline. [1]

KDIGO Diagnostic Thresholds

AKI is diagnosed by serum creatinine increase of ≥0.3 mg/dL within 48 hours. [1]
AKI is also diagnosed by serum creatinine increase to ≥1.5 times baseline within the prior 7 days. [1]

Application to the Given Values

The 0.4 mg/dL rise satisfies the ≥0.3 mg/dL within 48 hours threshold. [1]
The 1.27× rise does not satisfy the ≥1.5× baseline within 7 days threshold. [1]

Timing Required to Confirm AKI

If the creatinine rise to 1.9 mg/dL occurred within 48 hours of the 1.5 mg/dL baseline, AKI criteria are met. [1]
If the rise occurred outside 48 hours, AKI criteria would require documentation that the rise met the ≥1.5× baseline threshold within 7 days, which is not met by 1.9 mg/dL from a baseline of 1.5 mg/dL. [1]

Sources (1)

[1] Guideline 2012

KDIGO Clinical Practice Guideline for Acute Kidney Injury