CCDS Acute Kidney Injury and Renal Documentation 2 — Questions and Answers
Question 1: Which CKD stage corresponds to a GFR of 15–29 mL/min/1.73m²?
- Stage 3a
- Stage 3b
- Stage 4 (Correct answer)
- Stage 5
Correct answer: Stage 4
CKD Stage 4 is defined by a GFR of 15–29 mL/min/1.73m², representing severely decreased kidney function approaching end-stage disease.
Question 2: Which ICD-10-CM code is assigned for end-stage renal disease (ESRD) requiring renal replacement therapy?
- N18.5
- N18.6 (Correct answer)
- N17.9
- N19
Correct answer: N18.6
N18.6 is the specific ICD-10-CM code for ESRD, which is distinct from N18.5 (CKD Stage 5) and indicates dependency on dialysis or other renal replacement therapy.
Question 3: A patient with type 2 diabetes mellitus is documented with CKD Stage 3b. What is the correct ICD-10-CM coding approach?
- Assign E11.9 and N18.32 as unrelated diagnoses
- Assign E11.22 for diabetic chronic kidney disease plus N18.32 for the specific CKD stage (Correct answer)
- Assign only N18.32 since CKD is the complicating condition
- Assign only E11.9 since diabetes is the underlying cause
Correct answer: Assign E11.22 for diabetic chronic kidney disease plus N18.32 for the specific CKD stage
ICD-10-CM requires E11.22 (type 2 DM with diabetic CKD) paired with N18.32 (CKD Stage 3b) to capture both the diabetic etiology and the specific stage of CKD.
Question 4: According to ICD-10-CM guidelines, what relationship is assumed between hypertension and chronic kidney disease when both are documented?
- Hypertension and CKD are coded separately as unrelated conditions
- A causal relationship is assumed, requiring combination codes from category I12 (Correct answer)
- The physician must explicitly state that hypertension caused the CKD before linking them
- Hypertension is coded as a complication of CKD rather than its cause
Correct answer: A causal relationship is assumed, requiring combination codes from category I12
ICD-10-CM presumes a causal relationship between hypertension and CKD, requiring combination codes from category I12 without explicit provider documentation of causality.
Question 5: What does the clinical term 'acute-on-chronic kidney disease' indicate for ICD-10-CM coding purposes?
- A patient with CKD who has never experienced an acute kidney episode
- AKI superimposed on pre-existing CKD, requiring codes for both conditions (Correct answer)
- CKD that has recently advanced to a higher stage without an acute episode
- A temporary improvement in CKD function following treatment
Correct answer: AKI superimposed on pre-existing CKD, requiring codes for both conditions
Acute-on-chronic kidney disease indicates AKI has developed in a patient with underlying CKD; ICD-10-CM requires assigning codes for both AKI (N17.x) and the appropriate CKD stage (N18.x).
Question 6: Which laboratory finding is most consistent with pre-renal acute kidney injury?
- Urine sodium greater than 40 mEq/L
- Fractional excretion of sodium (FENa) greater than 2%
- BUN-to-creatinine ratio greater than 20:1 (Correct answer)
- Urine specific gravity less than 1.010
Correct answer: BUN-to-creatinine ratio greater than 20:1
A BUN-to-creatinine ratio >20:1 reflects intact tubular function with avid urea reabsorption, characteristic of pre-renal AKI where kidneys respond to reduced perfusion.
Question 7: When reviewing a medical record, which finding would most prompt a CDI specialist to initiate a query for a renal diagnosis?
- Documentation of 'renal insufficiency' with creatinine trending downward to normal
- Documentation of 'elevated creatinine' without any corresponding renal diagnosis (Correct answer)
- A creatinine of 1.0 mg/dL in a patient with a known baseline of 0.95 mg/dL
- Documentation of CKD Stage 2 with GFR confirmed at 65 mL/min
Correct answer: Documentation of 'elevated creatinine' without any corresponding renal diagnosis
When 'elevated creatinine' is documented without a corresponding coded renal diagnosis, CDI specialists have an opportunity to query for AKI or CKD if clinical criteria are met.
CCDS Acute Kidney Injury and Renal Documentation 2
Which CKD stage corresponds to a GFR of 15–29 mL/min/1.73m²?