Diagnostic Coding and Nuances You Should Know: CKD and Type 2 Diabetes

Nuances of diagnostic coding from the ICD-10-CM coding book include additional codes that supply further information relevant to the main diagnosis. A notation of “use additional code” or “code first” is found in the coding book’s tabular section to show the need for more clarification through the use of additional codes. These notes are a part of the Guidelines of ICD-10-CM coding and should not be forgotten or ignored.

It appears at times there is a lack of enforcement of the guidelines of the HIPAA identified code set. If claims are not rejected even though they fail to include an additional required code on the claim for a service, there is no real incentive to know or follow the rules for when those extra codes are required and when they are not. Coding software is also in-part to blame because it often does not indicate to the user that additional codes should be assigned. This column is intended to make you aware that situations exist where additional information should be included in the patient’s documentation and provided on claim forms. An example can be seen with codes associated with chronic kidney disease (CKD).

Many providers have patients with CKD. It may be a primary or a secondary diagnosis. It may also be a part of a complex code like diabetes with chronic kidney disease, hypertension in chronic kidney disease due to type 2 diabetes mellitus, or CKD due to type 2 diabetes mellitus. Interestingly, all three of these diagnoses code to the same ICD-10-CM code, E11.22.

Knowing when to append an additional code to classify the state of the chronic kidney disease should be intuitive based on the wording of the primary code. But let us look at what the “rules” of ICD-10-CM coding indicate.

The guidelines from the diagnostic code book under CKD states, “The ICD-10-CM classifies CKD based on severity. Just as CKD severity matters to the physician treating the patient it should be clarified within the code set for the patient. The severity of CKD is designated by stages 1-5.” There are also codes for unspecified CKD and end-stage renal disease. The guidelines define that stage 2 equates to mild disease, stage 3 equates to moderate disease, and stage 4 equates to severe disease. These apply to the codes from the N18 category.

If one looks at code E11.22, the code listed as an example above, there is a notation to use an additional code to identify the state of the chronic kidney disease from the N18 category. As a result, two codes are needed for patients with this diagnoses.

Another example of where CKD coding needs clarification of the stage is found when using the codes for hypertensive chronic kidney disease. The guidelines instruct the user to use two codes when the patient has both hypertension and a condition classifiable to category N18.

The guidelines address the classification of CKD when associated with a diagnosis of hypertensive heart disease. The guidelines instruct the user to assign codes from the combination category of I13, hypertensive heart and chronic kidney disease, when there is hypertension with both heart and kidney involvement. In addition, the notation in the code book is seen to use an appropriate code from category N18, CKD, as a secondary code when using a code from category I13 to identify the stage of CKD.

There are many areas of the ICD-10-CM code book that have these “extra” notations. CKD is just one example. For example, the guidelines under diabetes state, “Additional code(s) should be assigned from category Z79 to identify the long-term (current) use of insulin, oral hypoglycemic drugs or injectable non-insulin antidiabetic drugs.” This applies to type 2 diabetics coded from the E11 category. As a result, any Type 2 diabetic patient you manage should include the use of an additional code to show how their care is managed.

Check your coding software for the code E11.22 to see if there is a notation to classify the CKD with a code from N18. This code should also elicit a notation to code identify the type of medication the patient is using for the treatment of their diabetes.

If your software doesn’t give you these options, or even if it does, ask your billing staff to show you the page from the current ICD-10 book for these codes or others you may have questions about. You can ask them to show you the information found in the Chapter Specific Coding Guidelines for Chapter 4: Endocrine, Nutritional and Metabolic Diseases (E00-E89) to read about other guidelines that might affect your coding in this or other categories of codes.

This information, and small changes you may need to make in your documentation and coding, will not only make your notes more compliant according to the rules of ICD-10, but it will also make them audit proof should the full rules of ICD-10-CM, as mandated by HIPAA, start to be enforced