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  2. ICD-10-CM Codes List
  3. N00–N99
  4. N17-N19
  5. Chronic kidney disease (CKD) (N18)

Chronic kidney disease (CKD) (N18)

ICD-10 codes N18 and its subcategories classify chronic kidney disease (CKD) by stage and severity, from early stages (N18.1) to end stage renal disease (N18.6). These codes help healthcare providers and coders specify the exact progression of CKD, essential for diagnosis, treatment, and billing.

The codes range from N18.1 for stage 1 CKD, often linked to conditions like hypertension or diabetes (also referred to as nephropathy secondary to diabetes or benign hypertensive kidney disease), to N18.5 covering stage 5 or kidney failure requiring dialysis. Stage 3 is subdivided into 3a (N18.31) and 3b (N18.32), indicating moderate loss of kidney function. N18.6 designates end stage renal disease, often described as dependence on dialysis or renal replacement therapy. The unspecified CKD code (N18.9) covers cases where the stage is unknown, and it also includes associated complications like anemia or hypertensive heart disease. Using these specific codes ensures accurate identification of CKD severity and its causes, including hypertension and diabetes mellitus, aiding clinicians and coders in comprehensive patient care documentation and billing.

Instructional Notations

Code First

Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists, there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation.

Use Additional Code

The “use additional code” indicates that a secondary code could be used to further specify the patient’s condition. This note is not mandatory and is only used if enough information is available to assign an additional code.

  • code to identify kidney transplant status, if applicable, Z94.0

Clinical Terms

The following clinical terms provide additional context, helping users better understand the clinical background and common associations for each diagnosis listed in this section. Including related terms alongside ICD-10-CM codes supports coders, billers, and healthcare professionals in improving accuracy, enhancing documentation, and facilitating research or patient education.

Acute Kidney Injury

Abrupt reduction in kidney function. Acute kidney injury encompasses the entire spectrum of the syndrome including acute kidney failure; ACUTE KIDNEY TUBULAR NECROSIS; and other less severe conditions.

Hyperphosphatemia

A condition of abnormally high level of PHOSPHATES in the blood, usually significantly above the normal range of 0.84-1.58 mmol per liter of serum.

Nephrosclerosis

Hardening of the KIDNEY due to infiltration by fibrous connective tissue (FIBROSIS), usually caused by renovascular diseases or chronic HYPERTENSION. Nephrosclerosis leads to renal ISCHEMIA.

Phosphates

Inorganic salts of phosphoric acid.

Renal Insufficiency

Conditions in which the KIDNEYS perform below the normal level in the ability to remove wastes, concentrate URINE, and maintain ELECTROLYTE BALANCE; BLOOD PRESSURE; and CALCIUM metabolism. Renal insufficiency can be classified by the degree of kidney damage (as measured by the level of PROTEINURIA) and reduction in GLOMERULAR FILTRATION RATE.

Renal Insufficiency, Chronic

Conditions in which the KIDNEYS perform below the normal level for more than three months. Chronic kidney insufficiency is classified by five stages according to the decline in GLOMERULAR FILTRATION RATE and the degree of kidney damage (as measured by the level of PROTEINURIA). The most severe form is the end-stage renal disease (CHRONIC KIDNEY FAILURE). (Kidney Foundation: Kidney Disease Outcome Quality Initiative, 2002)

Vitamin D Deficiency

A nutritional condition produced by a deficiency of VITAMIN D in the diet, insufficient production of vitamin D in the skin, inadequate absorption of vitamin D from the diet, or abnormal conversion of vitamin D to its bioactive metabolites. It is manifested clinically as RICKETS in children and OSTEOMALACIA in adults. (From Cecil Textbook of Medicine, 19th ed, p1406)