Keep in mind these coding tips to improve medical record documentation

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.

The hypertension table in the ICD-9-CM Alphabetic Index is the first point of reference when coding hypertension. It classifies hypertension by type, primary or secondary, and by nature, benign, malignant or unspecified. There are 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 401 to 404 are used for primary hypertension.
• Secondary hypertension is due to an underlying cause and is reported with codes from category 405.
• Documentation of hypertension should also specify if it’s benign or malignant:
• 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.
• If hypertension is not documented as benign or malignant, it’s reported as unspecified hypertension (401.9). Coders can’t determine if hypertension is benign or malignant; 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.
• Use of the words controlled or uncontrolled to describe hypertension refers to the status of the condition, not whether it’s benign or malignant. Status indicates if it’s responding to medication, diet or other therapy, not if it’s benign or malignant. For example, documentation that states hypertension, controlled should be coded as 401.9 (hypertension, unspecified), not 401.1 (malignant hypertension).   
• Documentation that indicates elevated or high blood pressure, or borderline hypertension, but doesn’t state a diagnosis of hypertension, is reported with 796.2 (elevated blood pressure reading with no mention of hypertension). 

Hypertension and correct coding
There are three codes for primary (essential) hypertension in its most simple vascular state:

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. 

When documentation indicates a cardiac condition is due to hypertension, caused by hypertension or hypertensive, report a combination code from category 402. Providers must establish causality in the documentation. Causality can’t be assumed.

Conditions classifiable to category 402 are indicated in the subterms and include cardiomyopathy, myocarditis, myocardial degeneration, cardiovascular disease, cardiomegaly, heart disease and conditions from 429.81 to 420.89 (other ill-defined heart diseases).

Additional codes from category 428 may also be documented and reported for the type of heart failure. Hypertensive heart disease doesn’t include conditions classifiable to ischemic heart disease (410 to 414); however, these might also be documented in the medical record and should be coded separately. 

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 CKD, and the association between hypertension and CKD is so strong that ICD-9-CM presumes a cause-and-effect relationship between the two conditions. 

A code from category 585 should also be used to document the stage of CKD.

Only chronic kidney conditions classified to category 585 or 587 can be reported with the hypertensive CKD 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 affect of medicine, and it’s often reversible. In contrast, chronic kidney disease is caused by the affects 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 increases and the likelihood of heart problems increases, too. Due to their interactive nature, category 404 combines three conditions: heart disease, hypertension and CKD. As previously indicated, a relationship between CKD 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 CKD. 

Secondary hypertension
Secondary hypertension is coded using category 405. It’s defined as high arterial blood pressure due to another underlying cause or primary disease, such as 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-9-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.

Be sure to check out next month’s edition of The Record, which will include an article about coding tips for chronic kidney disease.

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