ICD 10 Coding Alert

Debunk these 3 myths to sail through allergy diagnosis codes.

With allergy season in full swing, you need to be ready to report diagnoses involving allergic conditions correctly; however, that’s not always easy. In addition to the sheer number of allergy codes, you have to understand the nuances behind each one and how some allergy codes play off of other conditions; this coding concept can take quite some time to master.

Dive in to quash these three common allergy diagnosis coding myths we’ve compiled to help you clear up any lingering confusion.

Myth 1: T codes are used to report unspecified allergies until a cause is identified.

Sometimes, but not always. The key to choosing the right code for a patient with allergies not otherwise specified (NOS) is knowing whether they are experiencing an acute reaction.

In many initial encounter visits, the cause of the allergy will be unknown to both the patient and provider. However, this does not mean that you should opt for the unspecified code T78.40- (Allergy, unspecified). T codes fall under the category of “Injury, poisoning and certain other consequences of external causes” within the ICD-10-CM code book. Unless the patient is having an acute allergic reaction, you should not consider a T code diagnosis.

“If a patient presents with allergies of an unspecified nature without an acute allergic reaction taking place, you should only code the signs and symptoms until an allergy test has been performed,” explains Barbara J. Cobuzzi MBA, CPC, COC, CPC-P, CPC-I, CENTC, CPCO, CMCS, of CRN Healthcare Solutions of Tinton Falls, New Jersey.

Tip: If a patient does present with an initial, acute allergic reaction NOS, you will opt for code T78.40XA (Allergy, unspecified, initial encounter), indicating that this is the first encounter for the patient’s presenting problem. Your other 7th character options are D (… subsequent encounter) and S (… sequela). If the patient is returning for a follow-up after receiving, for example, a nasal spray treatment, the use of the 7th character D would be appropriate.

Myth 2: Pet allergies aren’t classified as allergic rhinitis.

If the provider diagnoses the patient with allergic rhinitis due to pet hair or dander from a cat or dog, then you’ll turn to subcategory J30.8- (Other allergic rhinitis). This subcategory requires a 5th character to specify the type of allergic rhinitis.

Scenario: An established patient presents to the clinic with complaints of runny nose, sneezing, nasal congestion, and itchy eyes. The patient has been diagnosed with mild persistent asthma, but recently, their condition has flared up. The patient also attests to recently adopting a cat. After capturing the patient’s history and performing a physical examination, the provider diagnoses the patient with acute exacerbation of mild persistent asthma due to cat hair and dander.

“The cause and effect of asthma must be documented and coded,” says Sheri Poe Bernard, CPC, CRC, CDEO, CCS-P, CPC-I, managing consultant at Granite GRC Consulting in Salt Lake City. “If there is an exacerbation, providers must identify the cause. This will require two codes: one to specify the asthma and one for the allergy or other cause of exacerbation.”

So for this case, you’ll need two ICD-10-CM codes to report the diagnosis. You’ll start with J45.31 (Mild persistent asthma with (acute) exacerbation) for the patient’s asthma flare-up. Then, you’ll assign J30.81 (Allergic rhinitis due to animal (cat) (dog) hair and dander) to report the cat allergy.

Definition: In allergic rhinitis, a person’s nose gets irritated when they breathe in something they’re allergic to — seasonal airborne allergens (i.e., mold spores, pollens from trees, grass, and weeds) or year-round allergens (i.e., dust and cat/dog dander). Their immune system overreacts to something in the environment that typically causes no problems in most people.

Symptoms include, but are not limited to:

• Runny nose
• Nasal obstruction
• Post-nasal drip
• Red, watery eyes
• Sneezing
• Coughing
• Itchy nose, mouth, eyes, throat, skin, etc.

Allergic rhinitis is also known as hay fever; but patients don’t necessarily need to be exposed to hay to experience symptoms, and it doesn’t cause a fever.

Myth 3: Perennial allergic rhinitis is caused by flowers.

Perennials are flowers that bloom every year, but perennial allergic rhinitis isn’t necessarily related to flowers. In this case, perennial refers to allergies the patient experiences throughout the entire year rather than just allergy season.

Causes of perennial allergic rhinitis include:

• Dust mites
• Animal hair or dander
• Mold
• Cockroaches

You’ll assign J30.89 (Other allergic rhinitis) to report the diagnosis, as perennial allergic rhinitis is an additional synonym for the code. You’ll also report J30.89 when the provider documents a specific cause of the patient’s allergic rhinitis, but the ICD-10-CM code set doesn’t include a code that matches that exact condition. “The ‘other’ code — although not an unspecified code — becomes a catch-all code for whatever does not have a specific code assigned in ICD-10,” Cobuzzi notes.

Remember: The More Documentation, the Better

Taking a brief look at “allergy” in the ICD-10-CM index, you’ll see the plethora of options to choose from. While the unspecified T codes (for allergic reactions) do cross-reference with allergy testing CPT^® codes in the coding crosswalk, the same cannot necessarily be said for evaluation and management (E/M) visits.

To ensure payment for these encounters, make sure your provider documents any and all information available surrounding the patient’s allergy diagnosis, “especially with the 2021/23 E/M guidelines, where the provider gets credit for their cognitive work,” says Cobuzzi. “Documenting their entire thought process, even rule-out diagnoses — which cannot have ICD-10 codes assigned to them but are counted in leveling the E/M as well as possible but deferred treatment plans — can possibly increase the level of the E/M.”