Coding corner update: Improve medical record documentation for hypertension

Beginning Oct. 1, 2015, the transition to ICD-10-CM will affect every area of health care. Many codes contain much greater specificity. This article includes updated codes to align with the transition to ICD-10-CM.

According to the Centers for Disease Control and Prevention, one in every three adults has hypertension and only half of those adults have it under control. If left uncontrolled for too long, hypertension can damage the heart, kidneys and other organs.

Coding of hypertension was simplified in ICD-10-CM as it is no longer classified by malignant, benign or unspecified. There is only one code, I10 Essential (primary) hypertension. Therefore there is no longer a table in the alphabetic index in the code book.

There are ICD-10-CM codes which are used for reporting hypertension in its simple vascular state, without manifestations, and combination codes that illustrate the affect of hypertension on other organs. This allows providers to communicate the complexity of their patient’s condition to the greatest specificity — whether the condition exists alone or with other diseases.

Coding tips for hypertension
Here are common codes for hypertension:

• Primary or essential hypertension is considered idiopathic — occurring without apparent cause. Code categories I10 to I13 are used for primary hypertension.
• Secondary hypertension is due to an underlying cause and is reported with codes from category I15. Code also the underlying condition.
• Although ICD-10-CM classifies benign or malignant hypertension to one code, I10- Essential (primary) hypertension, the documentation in the medical record should be specific.
• According to the National Institutes of Health, malignant hypertension is defined as high blood pressure that comes on suddenly and quickly. Malignant hypertension often causes organ damage. Other terms for malignant hypertension include accelerating or necrotizing.
• Benign hypertension is mild to moderate elevation in blood pressure of prolonged or chronic duration without target organ damage.
• Hypertension is benign or malignant and it must be documented in the progress note by the provider.

• Documentation should indicate hypertension, benign, or hypertension, malignant. Documentation that states only elevated or high blood pressure could be misinterpreted as transient or incidental hypertension.

• Documentation that indicates elevated or high blood pressure, or borderline hypertension, but doesn’t state a diagnosis of hypertension, is reported with R03.0 (elevated blood pressure reading without diagnosis of hypertension).

Hypertension and correct coding
ICD-10-CM classifies hypertension by type as essential or primary (code I10, essential (primary) hypertension and secondary (category I15). An additional code to identify tobacco use or exposure should be listed if applicable.

Hypertensive heart disease
Hypertension may increase the workload of the left ventricle of the heart due to the higher systemic vascular resistance. This can result in hypertrophy of the heart or combined hypertrophy and dilation, also known as heart disease.

Heart conditions classified to I50.– or I51.4-I51.9, are assigned to a code from category I11, Hypertensive heart disease, when a causal relationship is stated (due to hypertension) or implied (hypertensive). Providers must establish causality in the documentation in order for the combination code to be assigned since causality can’t be assumed. When using codes from category I11, use an additional code from category I50 heart failure to identify the type of heart failure when present. The same heart conditions (I50.–, I51.4-I51.9) with hypertension, but without a stated causal relationship, are coded separately. Make sure to sequence according to the circumstances of the encounter.

Hypertensive chronic kidney disease
According to the National Kidney Foundation, hypertension is the leading cause of chronic kidney disease. It can also be a complication of chronic kidney disease, and the association between hypertension and chronic kidney disease is so strong that ICD-10-CM presumes a cause and effect relationship between the two conditions.

A code from category N18 should also be used to document the stage of chronic kidney disease.

Only chronic kidney conditions classified to category N18 can be reported with the hypertensive chronic kidney disease codes. There isn’t an assumed causal relationship between hypertension and acute renal failure, which usually develops as the result of an event such as dehydration, major blood loss or the side effect of medication, and it’s often reversible. In contrast, chronic kidney disease is caused by the effects of hypertension or other diseases over a long period of time.

Hypertensive heart and chronic kidney disease
The kidneys play an important role in regulating blood pressure. But when they develop disease, blood pressure can increase and the likelihood of heart problems can increase as well. Due to their interactive nature, category I13 combines three conditions: heart disease, hypertension and chronic kidney disease. As previously indicated, a relationship between chronic kidney disease and hypertension can be assumed, but documentation must indicate a causal relationship between hypertension and heart disease.

Additional codes should be added to indicate the type of heart failure and stage of chronic kidney disease.

Secondary hypertension
Secondary hypertension is coded using category I15. It’s defined as high arterial blood pressure due to another underlying cause or primary disease, such as a renal disorder, central nervous system disorders, endocrine or vascular diseases. A code should be reported for the type of secondary hypertension and also a code for the underlying etiology.

Hypertension may contribute or accelerate the development of many other conditions. Because ICD-10-CM doesn’t provide combination codes for every condition, assign a code for each individual condition to communicate the complexity of a patient’s condition.

ICD-10 coding for all conditions should follow coding conventions, chapter specific guidelines and general coding guidelines.

If you have questions or need more information, contact your provider consultant.

None of the information included in this article is intended to be legal advice and, as such, it remains the provider’s responsibility to ensure that all coding and documentation are done in accordance with applicable state and federal laws and regulations.