January 21, 2008

Coding for Food Allergy
For The Record
Vol. 20 No. 2 P. 25

Food allergy is defined as a reaction triggered by the immune system. Also documented as food hypersensitivity, the immune system mistakenly identifies a specific food or food component as a harmful substance. The immune system triggers immunoglobulin E antibodies and releases histamines into the bloodstream. The common foods that can cause an allergy are eggs, peanuts, fish, shellfish, tree nuts, milk, wheat, and soy.

Food allergy is different than food intolerance, which includes unpleasant symptoms triggered by food but does not involve the immune system. The symptoms of an intolerance are typically not as severe as a food allergy.

The appropriate ICD-9-CM code assignment will depend on the patient’s response to the food allergy. A gastrointestinal manifestation is classified to code 558.3, Allergic gastroenteritis and colitis. This code includes colitis, gastroenteritis, and milk protein. Allergic rhinitis is classified to code 477.1.

An atopic food allergy is classified to code 691.8. If the dermatitis was due to food in contact with the skin, assign code 692.5. Code 693.1 is assigned for dermatitis due to food taken internally. This code is also used if the food allergy is unspecified. Code 995.7 is assigned for other adverse food reactions, not elsewhere classified. Also assign additional codes to identify the type of reaction such as hives (708.0) and wheezing (786.07).

Symptoms
Signs and symptoms can develop within a few minutes to an hour after eating the food. When the symptoms do develop, they may include the following:

• tingling in the mouth;

• hives;

• itching;

• eczema;

• rash;

• swelling of the lips, face, tongue, and throat;

• wheezing;

• nasal congestion;

• breathing difficulties;

• abdominal pain or cramps;

• diarrhea;

• nausea and vomiting; and/or

• dizziness, lightheadedness, or fainting.

A severe allergic reaction to food is called anaphylaxis. Signs and symptoms of anaphylaxis include the following:

• quick swelling of the throat and tongue;

• airway constriction causing breathing trouble;

• shock;

• rapid pulse; and/or

• dizziness, lightheadedness, or loss of consciousness.

This condition is life threatening and must be treated immediately. Anaphylaxis (anaphylactic shock) is classified to code 995.6x. A fifth digit is needed to identify the food causing the condition and includes the following:

• 995.60, due to unspecified food;

• 995.61, due to peanuts;

• 995.62, due to crustaceans;

• 995.63, due to fruits and vegetables;

• 995.64, due to tree nuts and seeds;

• 995.65, due to fish;

• 995.66, due to food additives;

• 995.67, due to milk products;

• 995.68, due to eggs; and

• 995.69, due to other specified food.

Other Types of Food Allergy
Occasionally, a patient may experience exercise-induced food allergy. The symptoms of this condition include itchiness and lightheadedness. In severe cases, a patient may experience hives or anaphylaxis. This type of food allergy may be prevented by not eating for a few hours prior to exercising.

Oral allergy syndrome is a type of food allergy caused by fresh fruits and vegetables that may cause mouth tingling and itching. The proteins in fruits and vegetables cause the reaction because they are similar to those allergy-causing proteins found in certain pollen. Most cooked fruits and vegetables do not cause cross-reactive oral allergy symptoms.

Coding and sequencing for food allergy are dependent on the physician documentation in the medical record and application of the Official Coding Guidelines for inpatient care. Also, use specific AHA Coding Clinic for ICD-9-CM and American Medical Association CPT Assistant references to ensure complete and accurate coding.

— This information was prepared by Audrey Howard, RHIA, of 3M Consulting Services. 3M Consulting Services is a business of 3M Health Information Systems, a supplier of coding and classification systems to nearly 5,000 healthcare providers. The company and its representatives do not assume any responsibility for reimbursement decisions or claims denials made by providers or payers as the result of the misuse of this coding information. More information about 3M Health Information Systems is available at www.3mhis.com or by calling 800-367-2447.