The Risky Business of Coding CKD and ESRD

Author: Keisha Wilson CCS, CPC, CRC, CPB, CPMA, AAPC Approved Instructor

Published Originally by AAPC Healthcare Business Monthly:

Documentation is key for accurate risk adjustment of chronic and acute conditions.

The importance of documenting a patient’s chronic kidney disease (CKD) and/or end stage renal disease (ESRD) to allow coding to the highest level of specificity cannot be stressed enough. This, in turn, ensures accurate hierarchical condition category (HCC) coding and proper risk adjustment, thereby protecting the outcomes of the patient, the provider, and the payer. In this article, I’ll point out pertinent verbiage in the ICD-10-CM Official Guidelines for Coding and Reporting (guidelines) and other sources that direct us on how to document and code a patient’s CKD and/or ESRD diagnosis.

Start With Clinical Documentation Improvement

CKD and ESRD cannot be coded accurately if provider documentation lacks necessary information such as the disease process and an indication of the patient’s dialysis or kidney transplant status. The coder then has to query the provider for clarification or code unspecified diagnoses. To improve documentation and limit queries, providers should receive ongoing training for current documentation requirements, guidelines, and payer policies.

All new symptoms that may show disease progression or regression, complications, and side effects to treatment for the patient’s condition should be clearly stated throughout the record. In the outpatient setting, signs and symptoms can be used in the absence of a definitive diagnosis or “when the sign or symptom is not routinely associated with that diagnosis,” according to ICD-10-CM guideline I.C.18.b. The guideline continues, “Signs and symptoms that are associated routinely with a disease process should not be assigned as additional codes, unless otherwise instructed by the classification.” 

Providers should be aware that coding guidelines are different in the inpatient setting when it comes to coding uncertain diagnoses. ICD-10-CM guideline II.H states, “If the diagnosis documented at the time of discharge is qualified as ‘probable,’ ‘suspected,’ ‘likely,’ ‘questionable,’ ‘possible,’ or ‘still to be ruled out,’ ‘compatible with,’ ‘consistent with,’ or other similar terms indicating uncertainty, code the condition as if it existed or was established.”

Watch for combination codes that identify both the definitive diagnosis and common symptoms of that diagnosis. Never report symptom codes with a combination code, per ICD-10-CM guideline I.C.18.c.

Indicate Acute or Chronic

Another critical area in a provider’s documentation of CKD is the indication for whether the condition is acute or chronic. This information must be documented to ensure proper coding.

For example, per ICD-10-CM guideline Appendix I, acute conditions that are present at the time of admission are coded differently than acute conditions that are not present at the time of admission. And if the condition is described as both acute and chronic, you will code both and sequence the acute code first, if “separate subentries exist in the Alphabetic Index at the same indentation level,” per ICD-10-CM guideline I.B.8.

Indicate Stage

Documenting the stage of renal disease is also imperative for proper diagnosis coding; the stage shows the severity of the condition, which can affect HCC coding. Per ICD-10-CM guideline I.C.14.a(1), “The ICD-10-CM classifies CKD based on severity. The severity of CKD is designated by stages 1-5. Stage 2, code N18.2, equates to mild CKD; stage 3, codes N18.30-N18.32, equates to moderate CKD; and stage 4, code N18.4, equates to severe CKD. Code N18.6, End stage renal disease (ESRD), is assigned when the provider has documented end stage renal disease (ESRD).”

Providers determine the stage of kidney disease using the glomerular filtration rate (GFR), which is a math formula utilizing a person’s age, gender, and serum creatinine level. Coders and clinical documentation improvement specialists should not assign a code for CKD or ESRD by reviewing the patient’s GFR; providers should document the stage and address the GFR to code the final diagnosis.

A provider’s documentation of “renal insufficiency” does not mean a patient has CKD; you would not assign an N18.x code in this case. When using the ICD-10-CM Tabular List, renal insufficiency takes you to N28.9 unless the provider documents “chronic” renal insufficiency, which would bring you to N18.9, if no stage is mentioned.

Patients’ CKD stages can often change from one stage to the next slowly with time to ESRD, which will require dialysis or a kidney transplant. Therefore, not all stages of CKD may fall under an HCC, but that does not mean that it should not be documented and up to date in the record.

Establish a Link

ICD-10-CM guidelines also give clear direction on documentation requirements for patients with kidney transplants and reporting of their status. ICD-10-CM guideline I.C.14.a(2) states, “Patients who have undergone kidney transplant may still have some form of chronic kidney disease (CKD) because the transplant may not fully restore kidney function. Therefore, the presence of CKD alone does not constitute a transplant complication. Assign the appropriate N18 code for the patient’s stage of CKD and code Z94.0, Kidney transplant status.”

CKD and ESRD fall under HCC codes 134-138 and 184. The six HCC codes associated with renal status are (per CMS-HCC ESRD Model Category V24):

  • HCC 134 – Z99.2 Dependence on renal dialysis
  • HCC 135 – N17.9 Acute kidney failure, unspecified
  • HCC 136 – N18.5 Chronic kidney disease, stage 5
  • HCC 137 – N18.4 Chronic kidney disease, stage 4 (severe)
  • HCC 138 – N18.3 Chronic kidney disease
    • N18.30 Chronic kidney disease, stage 3 unspecified
    • N18.31 Chronic kidney disease, stage 3a
    • N18.32 Chronic kidney disease, stage 3b
  • HCC 136 – N18.6 End stage renal disease

Coding Checklist

As you analyze an encounter for CKD or ESRD, ask yourself the following questions:

  • How is this provider’s documentation showing that they are monitoring and managing any new signs/symptoms that may indicate the progression or regression of the disease?
  • What is the provider doing today to evaluate this condition, and what tests are they ordering?
  • What tests have the patient had in the past?
  • What are the provider’s findings and analysis of those past results?
  • Is GFR documented? Has the GFR range changed from the last visit, and is it documented? Or will the provider need to order new or further testing?
  • Is the stage of the disease clearly documented?
  • Was the patient on any prior medication?
  •  Is the patient on hemodialysis or peritoneal dialysis? What were the results/response of the medication and dialysis? Has it helped? If it did not help, did the provider explain how long the patient took the medication and what type of relief the patient experienced from the medication? Were there any adverse effects? Has the provider clearly documented any noncompliance with medication and treatment?
  • Is there a need for a kidney transplant? Or is the transplant status clearly documented?
  • What is the management of the CKD or ESRD?

Depending on documentation, often these conditions will require combination codes, as well as “trumping” of the HCC categories. Trumping is a risk adjustment model/logic that identifies that some of the patient’s chronic conditions can be related to other chronic conditions that fall within different HCC categories, thereby allowing only the highest category to be adjusted for risk.

Be sure to read Chapter 9: Diseases of the Circulatory System (I00-I99) for guidance on coding conditions with causal relationships.

Remember that guidelines and codes are updated annually on October 1. All providers, coders, and billing staff should be aware of the changes so that documentation and codes continue to be reported correctly and HCCs are accurately assigned.


FY 2024 ICD-10-CM Official Guidelines for Coding and Reporting, updated Oct. 1, 2023

National Kidney Foundation, Estimated Glomerular Filtration Rate (eGFR)

2019 Risk Adjustment Coding and HCC Guide. Optum360, LLC, 2018 2024 Model Software/ICD-10 Mappings

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