CCDS Acute Kidney Injury and Renal Documentation 1 — Questions and Answers
Question 1: According to KDIGO criteria, Stage 1 AKI is defined as an increase in serum creatinine of at least how much within 48 hours?
- 0.1 mg/dL
- 0.3 mg/dL (Correct answer)
- 0.5 mg/dL
- 1.0 mg/dL
Correct answer: 0.3 mg/dL
KDIGO defines Stage 1 AKI as a serum creatinine increase of ≥0.3 mg/dL within 48 hours or ≥1.5 times the patient's baseline within 7 days.
Question 2: Which ICD-10-CM code for acute kidney injury is classified as a Major Complication or Comorbidity (MCC)?
- N17.9 - Acute kidney failure, unspecified
- N17.0 - Acute kidney failure with tubular necrosis (Correct answer)
- N18.4 - Chronic kidney disease, Stage 4
- N18.6 - End-stage renal disease
Correct answer: N17.0 - Acute kidney failure with tubular necrosis
N17.0 (acute kidney failure with tubular necrosis) is classified as an MCC, while N17.9 (unspecified AKI) is only a CC, making specificity critical for MS-DRG impact.
Question 3: According to KDIGO urine output criteria, which finding is consistent with Stage 2 AKI?
- Less than 0.5 mL/kg/hr for more than 6 hours
- Less than 0.5 mL/kg/hr for more than 12 hours (Correct answer)
- Less than 0.3 mL/kg/hr for more than 24 hours
- Anuria for 12 or more hours
Correct answer: Less than 0.5 mL/kg/hr for more than 12 hours
KDIGO Stage 2 AKI by urine output is defined as less than 0.5 mL/kg/hr for more than 12 consecutive hours.
Question 4: When a patient has both acute kidney injury and underlying chronic kidney disease documented, what is the correct ICD-10-CM coding approach?
- Code only AKI since it is the more acute and significant condition
- Code only the applicable CKD stage
- Assign codes for both AKI and CKD to capture the complete clinical picture (Correct answer)
- Use a single combination code that covers both conditions without additional coding
Correct answer: Assign codes for both AKI and CKD to capture the complete clinical picture
ICD-10-CM guidelines instruct coders to assign separate codes for both AKI (N17.x) and CKD (N18.x) when both conditions are present and documented.
Question 5: Which clinical indicator would most support a CDI query for acute kidney injury in a hospitalized patient?
- Serum creatinine of 0.9 mg/dL with a baseline of 0.8 mg/dL
- Urine output of 600 mL over 8 hours in a 70 kg patient
- Serum creatinine rise of 0.4 mg/dL above baseline within 36 hours (Correct answer)
- Blood urea nitrogen of 15 mg/dL
Correct answer: Serum creatinine rise of 0.4 mg/dL above baseline within 36 hours
A creatinine increase of 0.4 mg/dL above baseline within 36 hours exceeds the KDIGO Stage 1 threshold of ≥0.3 mg/dL within 48 hours, supporting an AKI query.
Question 6: Which type of AKI etiology is most commonly associated with contrast-induced nephropathy?
- Pre-renal AKI due to volume depletion
- Intrinsic (intrarenal) AKI from tubular injury (Correct answer)
- Post-renal AKI from urinary obstruction
- Functional AKI from low cardiac output
Correct answer: Intrinsic (intrarenal) AKI from tubular injury
Contrast-induced nephropathy causes direct tubular cell injury, classifying it as intrinsic (intrarenal) AKI rather than pre-renal or post-renal.
Question 7: Why is it important for CDI specialists to query for a specific type of acute kidney injury rather than accepting 'acute kidney failure, unspecified'?
- Stage-specific AKI codes have no impact on MS-DRG assignment
- Specific AKI types such as tubular necrosis are MCCs while unspecified AKI is only a CC (Correct answer)
- Staging is only required for CKD documentation, not AKI
- Unspecified AKI always defaults to MCC status under MS-DRG grouping
Correct answer: Specific AKI types such as tubular necrosis are MCCs while unspecified AKI is only a CC
N17.0 (tubular necrosis) is classified as an MCC while N17.9 (unspecified AKI) is only a CC, meaning specificity directly impacts MS-DRG weight and reimbursement.
CCDS Acute Kidney Injury and Renal Documentation 1
According to KDIGO criteria, Stage 1 AKI is defined as an increase in serum creatinine of at least how much within 48 hours?