Nephrology involves the diagnosis and management of conditions affecting the kidneys, including chronic kidney disease (CKD), acute kidney injury (AKI), end-stage renal disease (ESRD), glomerular disorders, diabetic kidney disease, hypertension-related kidney disease and complications requiring dialysis.
Because nephrology patients often have several interconnected diagnoses, selecting the correct ICD-10 codes for nephrology can be more complex than simply choosing a code for kidney disease. The documented condition, severity, CKD stage, underlying cause and associated complications can all influence code selection.
Accurate ICD-10-CM coding supports appropriate medical necessity, cleaner claims, reliable clinical records and more efficient reimbursement. For nephrology practices, precise coding is also an important part of effective medical billing, claims processing and revenue cycle management.
As of October 1, 2026, U.S. healthcare organisations should use the FY 2027 ICD-10-CM code set for applicable patient encounters.
What Is ICD-10-CM in Nephrology?
ICD-10-CM stands for the International Classification of Diseases, Tenth Revision, Clinical Modification. Healthcare providers and medical coders use ICD-10-CM diagnosis codes to describe diseases, disorders, symptoms and other health conditions documented during a patient encounter.
Many nephrology diagnoses fall within Chapter 14: Diseases of the Genitourinary System (N00-N99). However, nephrology billing may also require codes from other ICD-10-CM chapters when kidney disease is associated with diabetes, hypertension, anaemia, cardiovascular disease or another underlying condition.
The correct code therefore depends on the complete clinical picture rather than the kidney diagnosis alone.
Common ICD-10 Codes for Nephrology
Below are several commonly encountered ICD-10-CM categories and codes used in nephrology. These examples should always be matched to the provider’s documentation and the current ICD-10-CM Tabular List.
Chronic Kidney Disease ICD-10 Codes
Chronic kidney disease is one of the most important conditions treated by nephrologists. ICD-10-CM differentiates CKD according to its documented stage.
| ICD-10 Code | Description |
| N18.1 | Chronic kidney disease, stage 1 |
| N18.2 | Chronic kidney disease, stage 2 (mild) |
| N18.30 | Chronic kidney disease, stage 3 unspecified |
| N18.31 | Chronic kidney disease, stage 3a |
| N18.32 | Chronic kidney disease, stage 3b |
| N18.4 | Chronic kidney disease, stage 4 (severe) |
| N18.5 | Chronic kidney disease, stage 5 |
| N18.6 | End stage renal disease |
| N18.9 | Chronic kidney disease, unspecified |
CMS states that ICD-10-CM classifies CKD according to severity and identifies stages 1 through 5. Stage 3 is further divided into stage 3a and stage 3b. When the provider documents ESRD, code N18.6 is assigned. If both a CKD stage and ESRD are documented, the official guidelines instruct coders to report N18.6 rather than coding both stages.
Documentation of the exact CKD stage is therefore particularly valuable for nephrology medical coding and billing.
ICD-10 Codes for Acute Kidney Injury
Acute kidney injury, also referred to in ICD-10-CM terminology as acute kidney failure, is generally reported from category N17.
Common codes include:
| ICD-10 Code | Description |
| N17.0 | Acute kidney failure with tubular necrosis |
| N17.1 | Acute kidney failure with acute cortical necrosis |
| N17.2 | Acute kidney failure with medullary necrosis |
| N17.8 | Other acute kidney failure |
| N17.9 | Acute kidney failure, unspecified |
The most appropriate code depends on the diagnosis documented by the treating provider. CMS continues to list these distinct acute kidney failure diagnoses in its ICD-10-CM coding classifications.
Coders should not infer a specific type of acute kidney injury solely from laboratory results or other clinical indicators when the required diagnosis has not been documented.
ICD-10 Codes for Hypertensive Chronic Kidney Disease
Hypertension and chronic kidney disease frequently occur together, making combination coding especially important in nephrology.
Relevant codes include:
I12.0 – Hypertensive chronic kidney disease with stage 5 CKD or ESRD
I12.9 – Hypertensive chronic kidney disease with stage 1 through stage 4 CKD or unspecified CKD
When hypertension and a condition classified to category N18 are both present, the ICD-10-CM guidelines generally direct coders to category I12, unless the provider documents that the CKD is unrelated to hypertension.
An additional N18 code is used to identify the patient’s CKD stage. CMS specifically instructs coders to use the appropriate N18 code with category I12.
For example, a patient documented with hypertension and stage 4 CKD may require both the appropriate hypertensive CKD code and N18.4 to communicate the severity of the kidney disease.
ICD-10 Codes for Hypertensive Heart and Chronic Kidney Disease
Patients may have hypertension, chronic kidney disease and heart disease simultaneously. In these circumstances, category I13 may become relevant.
Examples include:
I13.0 – Hypertensive heart and chronic kidney disease with heart failure and stage 1 through stage 4 CKD, or unspecified CKD
I13.11 – Hypertensive heart and chronic kidney disease without heart failure, with stage 5 CKD or ESRD
I13.2 – Hypertensive heart and chronic kidney disease with heart failure and stage 5 CKD or ESRD
Additional codes may be required to identify the CKD stage and type of heart failure.
Combination-code requirements are one reason why accurate nephrology documentation and experienced medical coding services are important. A claim that only captures one part of the patient’s condition may fail to represent the complete clinical picture.
ICD-10 Codes for Diabetic Chronic Kidney Disease
Diabetes is another major condition associated with kidney disease.
Examples include:
E10.22 – Type 1 diabetes mellitus with diabetic chronic kidney disease
E11.22 – Type 2 diabetes mellitus with diabetic chronic kidney disease
E13.22 – Other specified diabetes mellitus with diabetic chronic kidney disease
CMS continues to identify E11.22 as type 2 diabetes mellitus with diabetic chronic kidney disease in the FY 2027 classification.
When diabetic CKD is documented, an additional code from category N18 is typically needed to identify the CKD stage.
For example, documented type 2 diabetes with stage 3b CKD may involve E11.22 together with N18.32, subject to the complete record and applicable coding guidelines.
This level of specificity helps support accurate nephrology billing services, risk adjustment, clinical reporting and reimbursement.
ICD-10 Codes for Nephrotic Syndrome
Nephrotic syndrome has several ICD-10-CM codes depending on the underlying morphology or documented kidney disorder.
Examples include:
| ICD-10 Code | Description |
| N04.1 | Nephrotic syndrome with focal and segmental glomerular lesions |
| N04.20 | Nephrotic syndrome with diffuse membranous glomerulonephritis, unspecified |
| N04.21 | Primary membranous nephropathy with nephrotic syndrome |
| N04.22 | Secondary membranous nephropathy with nephrotic syndrome |
| N04.8 | Nephrotic syndrome with other morphologic changes |
| N04.9 | Nephrotic syndrome with unspecified morphologic changes |
The FY 2027 ICD-10-CM classification includes detailed nephrotic syndrome codes for different glomerular abnormalities, including membranous nephropathy and other morphologic findings.
Specific documentation can therefore be considerably more valuable than simply recording “nephrotic syndrome.”
ICD-10 Codes for Nephritic and Glomerular Disorders
Nephrologists also manage several forms of glomerular disease. These conditions may fall under ICD-10-CM categories such as:
N00.- – Acute nephritic syndrome
N01.- – Rapidly progressive nephritic syndrome
N02.- – Recurrent and persistent haematuria
N03.- – Chronic nephritic syndrome
N04.- – Nephrotic syndrome
N05.- – Unspecified nephritic syndrome
N06.- – Isolated proteinuria with specified morphological lesion
The current ICD-10-CM set also provides more specific classification for several glomerular disorders, including immunoglobulin A nephropathy, membranous nephropathy and C3 glomerulonephritis.
The code should reflect the diagnosis actually documented rather than assuming morphology from symptoms or test results.
Kidney Stone ICD-10 Codes
Kidney stones may also appear in nephrology records, although many patients with urinary calculi are managed jointly with urology.
Common ICD-10 codes include:
N20.0 – Calculus of kidney
N20.1 – Calculus of ureter
N20.2 – Calculus of kidney with calculus of ureter
The correct diagnosis should correspond with the documented location and nature of the calculus.
ICD-10 Codes for Other Kidney Conditions
Nephrology practices encounter many other renal disorders beyond CKD and AKI.
Examples include:
N25.0 – Renal osteodystrophy
N25.1 – Nephrogenic diabetes insipidus
N25.81 – Secondary hyperparathyroidism of renal origin
N28.1 – Cyst of kidney, acquired
N28.9 – Disorder of kidney and ureter, unspecified
The CMS classification includes renal osteodystrophy, nephrogenic diabetes insipidus and secondary hyperparathyroidism of renal origin within the broader group of conditions resulting from impaired renal tubular function.
ICD-10 Codes Related to Dialysis
Dialysis patients frequently require multiple diagnosis and status codes because ESRD, dialysis dependence and associated complications may need to be represented separately.
Two important examples are:
N18.6 – End stage renal disease
Z99.2 – Dependence on renal dialysis
A patient’s record may require additional codes depending on the encounter, underlying conditions, complications and services being provided.
Dialysis coding should therefore be based on the complete documentation rather than automatically assigning the same group of codes to every dialysis patient.
Kidney Transplant Status and ICD-10 Coding
A patient who has received a kidney transplant may continue to have CKD. ICD-10-CM specifically states that CKD alone does not automatically mean the transplanted kidney has developed a complication.
Z94.0 identifies kidney transplant status.
When CKD remains present after transplantation, the appropriate N18 code may also be assigned according to the documented stage. If transplant rejection, failure, infection or another transplant complication is documented, a different complication code may be necessary.
CMS identifies codes such as T86.11 for kidney transplant rejection, T86.12 for kidney transplant failure and T86.13 for kidney transplant infection.
The FY 2027 guidelines also specifically instruct coders to use the applicable N18 code with Z94.0 when CKD remains after transplantation unless an actual transplant complication is documented.
Why Accurate ICD-10 Coding Matters in Nephrology
Accurate nephrology coding is not simply an administrative requirement. It connects the provider’s clinical documentation with the claim submitted to the payer.
Correct coding can help a practice:
- Demonstrate medical necessity
- Accurately represent CKD severity
- Identify important comorbidities
- Reduce avoidable claim errors
- Support cleaner claim submission
- Improve reimbursement accuracy
- Strengthen clinical data reporting
- Reduce unnecessary coding-related denials
- Maintain more reliable patient records
Nephrology can be particularly challenging because conditions such as CKD frequently coexist with diabetes, hypertension, cardiovascular disease, anemia and mineral or bone disorders.
Effective revenue cycle management therefore requires alignment between clinical documentation, ICD-10-CM coding, CPT coding, payer requirements and claim submission.
Common Nephrology Coding Mistakes
Even relatively small documentation or coding issues can create problems later in the revenue cycle.
One common problem is reporting unspecified CKD when the medical record supports a documented stage. Another is failing to account for combination-code requirements involving diabetes or hypertension.
Other potential issues include failing to distinguish CKD from AKI, incorrectly coding transplant status as a transplant complication, missing relevant dialysis status information or selecting codes that do not accurately match the provider’s documentation.
Coding professionals should review the current ICD-10-CM Alphabetic Index, Tabular List, official coding guidelines and payer-specific requirements before finalising a claim.
Documentation Tips for More Accurate Nephrology Coding
Strong documentation makes accurate medical coding significantly easier.
Providers should clearly document the patient’s diagnosis and, where appropriate:
- CKD stage
- Acute versus chronic kidney disease
- Type of acute kidney injury
- Diabetes type and kidney involvement
- Hypertension and associated CKD
- ESRD status
- Dialysis dependence
- Type of glomerular disease
- Transplant status or documented transplant complication
- Relevant renal manifestations and comorbidities
Greater specificity can improve the connection between clinical care and nephrology medical billing while reducing unnecessary coder queries.
How Professional Nephrology Medical Billing Services Can Help
Nephrology billing involves more than assigning an ICD-10 code. Practices must manage insurance eligibility, charge capture, diagnosis and procedure coding, claim submission, payment posting, accounts receivable follow-up, denial management and payer-specific billing requirements.
Professional nephrology medical billing services can help establish a more consistent process from patient registration through final reimbursement.
Experienced medical billing and coding services can also review documentation for coding specificity, identify recurring denial patterns and monitor claims throughout the revenue cycle.
For practices managing complex CKD, dialysis and renal-care populations, an organised revenue cycle management strategy can reduce administrative pressure while helping physicians and clinical teams remain focused on patient care.
Final Thoughts
There is no single ICD-10 code that represents all of nephrology. Kidney diseases are classified across numerous categories according to the condition, severity, underlying cause and associated complications.
Some of the most frequently encountered codes include N18.1-N18.6 for staged chronic kidney disease, N17.- for acute kidney failure, N18.6 for ESRD, I12.- for hypertensive CKD and E11.22 for type 2 diabetes with diabetic CKD.
However, selecting the correct ICD-10 codes for nephrology requires careful review of the patient’s documentation and current coding rules.
Because ICD-10-CM is updated periodically, nephrology practices and coding teams should always verify codes against the current official code set before submitting claims. Accurate documentation, appropriate coding and organised medical billing services can work together to create cleaner claims and a healthier revenue cycle.
Frequently Asked Questions
1. What is the main ICD-10 code for chronic kidney disease?
There is no single CKD code for every patient. Codes N18.1 through N18.6 identify different CKD stages, while N18.9 represents unspecified chronic kidney disease.
2. What is the ICD-10 code for stage 3 chronic kidney disease?
Stage 3 CKD can be coded as N18.30 when unspecified, N18.31 for stage 3a or N18.32 for stage 3b when documented.
3. What is the ICD-10 code for stage 4 CKD?
N18.4 is the ICD-10-CM code for chronic kidney disease, stage 4 (severe). The diagnosis should be supported by the provider’s documented assessment.
4. What is the ICD-10 code for stage 5 CKD?
N18.5 represents chronic kidney disease, stage 5. If the provider specifically documents end-stage renal disease, N18.6 is used instead.
5. What is the ICD-10 code for end-stage renal disease?
N18.6 represents end-stage renal disease, or ESRD. Additional codes may be required for dialysis status, underlying conditions or other documented complications.
6. What is the ICD-10 code for acute kidney injury?
Acute kidney failure falls under category N17. N17.9 represents unspecified acute kidney failure, while more specific codes identify documented underlying types.
7. How is diabetic chronic kidney disease coded?
For type 2 diabetes with diabetic CKD, E11.22 is commonly reported along with an appropriate N18.- code identifying the documented CKD stage.
8. How is hypertension with chronic kidney disease coded?
Hypertension with CKD is generally coded using category I12, together with the appropriate N18.- code to identify the patient’s documented chronic kidney disease stage.
9. Does kidney transplant status have an ICD-10 code?
Yes. Z94.0 identifies kidney transplant status. A transplant complication should only be coded when failure, rejection, infection or another complication is documented.
10. Why is accurate ICD-10 coding important for nephrology billing?
Accurate diagnosis coding communicates disease severity and medical necessity, supports cleaner claims, improves clinical reporting and can reduce preventable denials within the nephrology revenue cycle.
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