First: we know that Coding guidelines require you to assume that certain kidney conditions (N18 and N26) in the setting of hypertension are due to hypertension unless otherwise documented in the chart. (ICD-10-CM Official Guidelines for Coding and Reporting FY 2020 p 47.) But what about the patient with diabetes, hypertension and CKD?
A recent Coding Clinic answers the question:
“Assign codes E11.22, Type 2 diabetes mellitus with diabetic chronic kidney disease, I12.9, Hypertensive chronic kidney disease with stage 1 through stage 4 chronic kidney disease, or unspecified chronic kidney disease, and N18.9, Chronic kidney disease, unspecified. The classification presumes a cause and effect relationship between both diabetes and CKD and hypertension and CKD. CKD is most likely related to both hypertension and diabetes when the patient has all three conditions. Both high blood sugar and high pressure in the blood vessels will cause the vessels to deteriorate, which can then damage the kidneys.”
More importantly, as a reference,in FY 2019 the Official Guidelines for Coding and Reporting were revised to read: "Assign codes from category I12, Hypertensive chronic kidney disease, when both hypertension and a condition classifiable to category N18, Chronic kidney disease (CKD), are present. CKD should not be coded as hypertensive if the provider indicates the CKD is not related to the hypertension.” (page 47 of the book, both for FY 2019 and 2020.)
Another interesting point came up around the same time. What about ARF due to dehydration in a transplant patient? Coding Clinics (ICD-10-CM/PCS Coding Clinic, Second Quarter ICD-10 2019 Page: 7) answered this question: “Assign codes T86.19, Other complication of kidney transplant, N17.9, Acute kidney failure, unspecified, and E86.0, Dehydration, to capture the effect on the transplanted kidney with the ARF and dehydration. Code T86.19 is assigned to capture the fact that the function of the transplanted kidney is affected by the ARF, but the transplant itself has not failed.”
FairCode keeps nuanced points such as this available to all our reviewing physicians in the "FairCode Brain."