A detailed review on Primary and secondary hypertension coding:

Hypertension (HTN), also known as high blood pressure is a common condition in which the blood pressure in the arteries is constantly elevated. Generally, the blood pressure is determined by the amount of blood your heart pumps and the amount of resistance to blood flow in your arteries. When your heart pumps more blood and your arteries are too narrowed, you experience a higher blood pressure.

Generally, there are two major types of Hypertension. They are Primary and secondary hypertension and the classification are mainly based on the reason for its occurrence.

Primary Hypertension (Essential hypertension):

A specific cause for primary hypertension is generally unknown. It is thought to be a combination of genetics, diet, lifestyle and age.

Secondary Hypertension:

Secondary hypertension is high blood pressure caused by another medical condition or disease. The underlying causes of secondary hypertension would include:

  • Chronic kidney disease
  • Obstructive sleep apnea
  • Tumors or other diseases of the adrenal gland
  • Aorta constriction
  • Thyroid dysfunction
  • Use of birth control pills

Coding Hypertension in ICD-10 CM:

The ICD-10 codes for the two major types of hypertension are listed below:

I10 – Primary (essential) hypertension

I15 – Secondary hypertension

  • I15.0 – Renovascular hypertension
  • I15.1 – Hypertension secondary to other renal disorders
  • I15.2 – Hypertension secondary to endocrine disorders
  • I15.8 – Other secondary hypertension
  • I15.9 – Secondary hypertension, unspecified

Use additional codes:

The hypertension codes I10-I15 requires an additional codes if the patient is a current or former tobacco user such as:

  • Exposure to environmental tobacco smoke (Z77.22)
  • history of tobacco use (Z87.891),
  • occupational exposure to environmental tobacco smoke (Z57.31),
  • nicotine dependence (F17.-) and
  • tobacco use (Z72.0).

Coders must be more watchful to pick up the relevant information from the medical record to assign these additional codes.

I10 – Primary (essential) hypertension

This code must be used for the individuals with hypertension who do not have additional disorders like heart or kidney disease. Code I10 is assigned when hypertension is described as:

  • Essential hypertension
  • Benign hypertension
  • Malignant hypertension
  • Systemic hypertension

It is highly significant to know that code I10 includes high blood pressure but it does not include “elevated blood pressure reading” without a diagnosis of hypertension. Therefore when the physician documents the patient has an elevated blood pressure, but a diagnosis of hypertension is not established, the coders should report ICD-10 CM code R03.0

R03.0 (elevated blood pressure reading without diagnosis of hypertension)

Case example: A 67-year-old patient is seen for benign hypertension. He continues to smoke two packs of cigarettes per day, and does not want to stop. BP is 165/110. Physician adjusts medications, counsels on smoking. Diagnosis is benign hypertension without good control, nicotine dependence.

  • I10 Hypertension
  • F17.210 Dependence, nicotine, cigarette, uncomplicated

Rationale: Hypertension, whether uncontrolled, untreated or not responding to current medication, is assigned code I10. An instructional note provided for categories I10-I15 states to use an additional code to identify exposure to environmental tobacco smoke (Z77.22), history of tobacco use (Z87.891), occupational exposure to environmental tobacco smoke (Z57.31), tobacco dependence (F17-) or tobacco use (Z72.0).

I15 – Secondary hypertension

Secondary hypertension is due to an underlying condition. Therefore two codes are required for a complete code assignment.

  • One code to identify the underlying etiology
  • Other code from category I15 to identify the hypertension.

The sequence of these codes is based on the primary reason for admission/encounter.

Case Example: A 57-year old patient was diagnosed for renovascular hypertension due to renal artery atherosclerosis.

I15.0 Renovascular hypertension

I70.1 Atherosclerosis of renal artery

Rationale: Secondary hypertension requires two codes: a code to identify the etiology and the appropriate I15 code to denote the hypertension.

Happy learning! Happy coding!



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